Software Raid 5 - Performance

Hi all,
we have a problem with a software RAID 5. Its read performance is acceptable (61 MB/s via UFS filesystem) while its write performance is very very bad. 3 MB/s through UFS filesystem is not acceptable for a machine with 6 1.35 GHz CPUs and 7 very fast (10K) fiberchannel disks.
Raid 1 write performance is okay (42 MB/s) as well as the performance of individual disks (read: 74 MB/s).
The RAID 5 includes 5 disks (140 GB each, 10K) and was built using the standard commands from the man page and online help.
The hardware: SunFire 890, 6 CPUs (1.35 GHz US IV), 24 GB Memory, 7 disks (140 GB, 10K each). The machine runs SunOS 5.10.
The question is: What are the options to speed up write performance of RAID 5?
A much cheaper Athlon 64 based Linux system with slower SATA disks is much faster in reading (180 MB/s) and writing (around 50 MB/s) on a similar software raid 5.
While searching the net I found some benchmarks that indicate that "normally" write and read on solaris software raid 5 should be nearly the same.
Are there any ideas what to do?
Greetinga and thanks in advance,
Jan

Hi,
thanks for your answer. But... I don't think this is the problem here. It is clear that these facts slow down the write process compared to the native write performance of the underlying disks, but the slowdown is IMO one order of magnitude too high.
As already mentioned... an Athlon Linux system with 4 disks has also a slowdown in write performance (compared to reading) but write performance is still 25%...30% of read performance. For this sun machine it is 5% of read performance. If the problem would be caused by contention and queuing it should apply there also, right?
Or, to use the measurements: The Athlon with linux has around 50 MB/s write and 180 MB/s read which makes sense for a fileserver with Gigabit ethernet. The sun has 61 MB/s read which is acceptable for such a server while the writing speed of 3 MB/s is even too slow for a single 100 MBit/s client.
Some benchmarks that I found on the net does not show such a big performance gap between read and write on Solaris software RAID 5 so I still guess there is a fundamental problem in our installation.
What about others... has anyone numbers from experiments such as writing 1 GB with dd to an empty partition and measure the time for that? The same for reading... after reboot or remount in order to empty the fs cache.
Greetings,
Jan

Similar Messages

I have some questions regarding setting up a software RAID 0 on a Mac Pro

I have some questions regarding setting up a software RAID 0 on a Mac pro (early 2009).
These questions might seem stupid to many of you, but, as my last, in fact my one and only, computer before the Mac Pro was a IICX/4/80 running System 7.5, I am a complete novice regarding this particular matter.
A few days ago I installed a WD3000HLFS VelociRaptor 300GB in bay 1, and moved the original 640GB HD to bay 2. I now have 2 bootable internal drives, and currently I am using the VR300 as my startup disk. Instead of cloning from the original drive, I have reinstalled the Mac OS, and all my applications & software onto the VR300. Everything is backed up onto a WD SE II 2TB external drive, using Time Machine. The original 640GB has an eDrive partition, which was created some time ago using TechTool Pro 5.
The system will be used primarily for photo editing, digital imaging, and to produce colour prints up to A2 size. Some of the image files, from scanned imports of film negatives & transparencies, will be 40MB or larger. Next year I hope to buy a high resolution full frame digital SLR, which will also generate large files.
Currently I am using Apple's bundled iPhoto, Aperture 2, Photoshop Elements 8, Silverfast Ai, ColorMunki Photo, EZcolor and other applications/software. I will also be using Photoshop CS5, when it becomes available, and I will probably change over to Lightroom 3, which is currently in Beta, because I have had problems with Aperture, which, until recent upgrades (HD, RAM & graphics card) to my system, would not even load images for print. All I had was a blank preview page, and a constant, frozen "loading" message - the symbol underneath remained static, instead of revolving!
It is now possible to print images from within Aperture 2, but I am not happy with the colour fidelity, whereas it is possible to produce excellent, natural colour prints using its "minnow" sibling, iPhoto!
My intention is to buy another 3 VR300s to form a 4 drive Raid 0 array for optimum performance, and to store the original 640GB drive as an emergency bootable back-up. I would have ordered the additional VR300s already, but for the fact that there appears to have been a run on them, and currently they are out of stock at all, but the more expensive, UK resellers.
I should be most grateful to receive advice regarding the following questions:
QUESTION 1:
I have had a look at the RAID setting up facility in Disk Utility and it states: "To create a RAID set, drag disks or partitions into the list below".
If I install another 3 VR300s, can I drag all 4 of them into the "list below" box, without any risk of losing everything I have already installed on the existing VR300?
Or would I have to reinstall the OS, applications and software again?
I mention this, because one of the applications, Personal accountz, has a label on its CD wallet stating that the Licence Key can only be used once, and I have already used it when I installed it on the existing VR300.
QUESTION 2:
I understand that the failure of just one drive will result in all the data in a Raid 0 array being lost.
Does this mean that I would not be able to boot up from the 4 drive array in that scenario?
Even so, it would be worth the risk to gain the optimum performance provide by Raid 0 over the other RAID setup options, and, in addition to the SE II, I will probably back up all my image files onto a portable drive as an additional precaution.
QUESTION 3:
Is it possible to create an eDrive partition, using TechTool Pro 5, on the VR300 in bay !?
Or would this not be of any use anyway, in the event of a single drive failure?
QUESTION 4:
Would there be a significant increase in performance using a 4 x VR300 drive RAID 0 array, compared to only 2 or 3 drives?
QUESTION 5:
If I used a 3 x VR300 RAID 0 array, and installed either a cloned VR300 or the original 640GB HD in bay 4, and I left the Startup Disk in System Preferences unlocked, would the system boot up automatically from the 4th. drive in the event of a single drive failure in the 3 drive RAID 0 array which had been selected for startup?
Apologies if these seem stupid questions, but I am trying to determine the best option without foregoing optimum performance.

Well said.
Steps to set up RAID
Setting up a RAID array in Mac OS X is part of the installation process. This procedure assumes that you have already installed Mac OS 10.1 and the hard drive subsystem (two hard drives and a PCI controller card, for example) that RAID will be implemented on. Follow these steps:
1. Open Disk Utility (/Applications/Utilities).
2. When the disks appear in the pane on the left, select the disks you wish to be in the array and drag them to the disk panel.
3. Choose Stripe or Mirror from the RAID Scheme pop-up menu.
4. Name the RAID set.
5. Choose a volume format. The size of the array will be automatically determined based on what you selected.
6. Click Create.
Recovering from a hard drive failure on a mirrored array
1. Open Disk Utility in (/Applications/Utilities).
2. Click the RAID tab. If an issue has occurred, a dialog box will appear that describes it.
3. If an issue with the disk is indicated, click Rebuild.
4. If Rebuild does not work, shut down the computer and replace the damaged hard disk.
5. Repeat steps 1 and 2.
6. Drag the icon of the new disk on top of that of the removed disk.
7. Click Rebuild.
http://support.apple.com/kb/HT2559
Drive A + B = VOLUME ONE
Drive C + D = VOLUME TWO
What you put on those volumes is of course up to you and easy to do.
A system really only needs to be backed up "as needed" like before you add or update or install anything.
/Users can be backed up hourly, daily, weekly schedule
Media files as needed.
Things that hurt performance:
Page outs
Spotlight - disable this for boot drive and 'scratch'
SCRATCH: Temporary space; erased between projects and steps.
http://en.wikipedia.org/wiki/StandardRAIDlevels
(normally I'd link to Wikipedia but I can't load right now)
Disk drives are the slowest component, so tackling that has always made sense. Easy way to make a difference. More RAM only if it will be of value and used. Same with more/faster processors, or graphic card.
To help understand and configure your 2009 Nehalem Mac Pro:
http://arstechnica.com/apple/reviews/2009/04/266ghz-8-core-mac-pro-review.ars/1
http://macperformanceguide.com/
http://www.macgurus.com/guides/storageaccelguide.php
http://www.macintouch.com/readerreports/harddrives/index.html
http://macperformanceguide.com/OptimizingPhotoshop-Configuration.html
http://kb2.adobe.com/cps/404/kb404440.html

Software RAID Failure - my experience and solution

I just wanted to share this information with the iCloud community.
I searched a bit and did not find much information that was useful with regard to my software RAID issue.
I have 27 inch Mid 2011 iMac with SSD and Hard drive which has been great.
I added an external hard drive (I think if I mention any brand name the moderator will delete this post) which includes an nice aluminum case with two 3 TB hard drives within it, and it has a big blue light on the front and is connected via Thunderbolt. This unit is about 2 years old and I have it configured in a 3 TB mirrored RAID (RAID 1) via a software RAID configured via Mac OS Disk Utility.
I had at one point a minor glitch which was fixed using another piece of software (again if I mention a brand the moderator will delete this post) which is like a 'Harddrive Fighter' or similar type name LOL.   So otherwise that RAID has served me well as a site for my Time Machine back up and Aperture Vault, etc. (I created a 1.5 TB Sparse bundle for Time Machine so that the backup would not use the entire 3 TBs)
I recently purchased a second aluminum block of drives, and set that up as a 4 TB RAID 1.
Each of the two RAIDs are set with the option of “Automatically rebuild RAID mirror sets” checked.
I put only about 400 gb on the new RAID to let it sit for a ‘burning in period.’
A few days ago the monitoring software from the vendor who sells the aluminum block of drives told me I had a problem. One of the drives had “Failed.”   The monitoring software strangely enough does not distinguish the drives so you can figure out which pair had the issue, so I assumed it was the New 8 TB model. Long story short, it was the older 6 TB model, but that does not matter for this discussion.
I contacted the vender and this is part of their response.
“This is an indication that the Disk Utility application in Mac had a momentary problem communicating with the drive mechanism. As a result, it marked that drive as "failed" in the header information. Unfortunately, once this designation is applied to a drive by the OS, the Disk Utility will thereafter refuse to attempt any further operations with that disk until the incorrect "failed" marker is manually cleared off the drive.”
That did not sound very good to me…..back up killed by a SOFTWARE GLITCH?
“The solution is to remove the corrupted volume header, and allow the generation of a new one….This command will need to be done for each disk in the array… (using Terminal)…
diskutil zerodisk (identifier)
…3. After everything is finished, you should be able to exit Terminal, and go back into the Disk Utility Application to re-configure the RAID array on the device.”
Furthermore they said.
“If the Disk Utility has placed a flag into the RAID array header (which exists on both drives) then performing this procedure on a single drive will not correct anything.”
And…
“When a drive actually does fail, it typically stops appearing in the Disk Utility application altogether. In that circumstance, it will never be marked "failed" by the Disk Utility, so the header erase operation is not needed.”
This all sounded like a bad idea to me. And what does the Vendors RAID monitor software say then? “Disk Really Really FAILED, check for a fire.”
As I tried to figure out which drive was actually the bad RAID pair I stumbled on a solution.
First I noted that the OS Disk Utility did NOT show a fault in the RAID. It listed both RAIDS as “Online.’ Thus no rebuilding was needed and it did not begin the rebuild process.
The Vendors disk monitor software saw some fault, but Mac was still able to read and write to the RAID, both disks in the mirror. I wrote a folder to the RAID and with various rebooting steps I pulled the “Bad” drive and looked at the “Good” Drive….the folder was there…I put the Bad drive back in and pulled the Good Drive and the folder was there on the “bad” drive. So it wrote to both drives. AND THE VENDORS MONITORING SOFTWARE SHOWED THE PREVIOUSLY LABELED ‘BAD’ DRIVE AS ‘GOOD’ AND THE MISSING DRIVE SLOT AS ‘BAD’.
My stumbled FIX.   I moved a bunch of files off the failed RAID to the new RAID but before I moved the sparse bundle, a folder of 500 gigs movies and some other really big folders the DISK UTILITY WINDOW (which I still had open) now showed that the RAID had a Defect and began rebuilding the mirror set itself, out of the blue!   I don't know why this happened. But moving about 1/2 of the data off of it perhaps did something? Any Ideas?
This process took a few hours as best I can tell (let it run overnight) and the next day the RAID was fine and the Vendors RAID monitor did not show a fault any longer.
So, the Vendors RAID monitoring software reporting a “FAILED” drive without any specific error codes to look up. Perhaps they could have more info for the user on the specific fault? The support line of the the Vendor said with certainty “the Volume Header is corrupted” and THE ONLY FIX is to completely ZERO THE DRIVE! This was not necessary as it turns out.
And the stick in the eye to me…..
“I've also sometimes seen the drives get marked as "failed" by the disk utility due to a shaky connection. In some cases, swapping the ends of the Thunderbolt cable will help with this. Something to try, perhaps, if your problems come back. “
Ya Right…..
Mike

Follow up.
After going through the Zeroing process and rebuilding the RAID set three times, with various configurations, LaCie finally agreed to repair the unit under warrantee.
I tried swapping the power supplies and thunderbolt wires, tried taking the drive out of series with the newer big brother of it. And it still failed after a few days.
I just wanted to share more of what I learned with regard to rebuilding the RAID sets via the Terminal. The commands can be typed partially and a help paragraph will come up to give VERY cryptic descriptions of the proper use of the commands.
First Under terminal you can used the command "diskutil appleRAID list" to list those drives which are in the RAID. This gives you the ID number for each physical drive. For example:
AppleRAID sets (1 found)
===============================================================================
Name:                 LaCie RAID 3TB
Unique ID:            84A93ADF-A7CA-4E5A-B8AE-8B4A8A6960CA
Type:                 Mirror
Status:               Online
Size:                 3.0 TB (3000248991744 Bytes)
Rebuild:              manual
Device Node:          disk4
# DevNode   UUID                                  Status     Size
0 disk3s2   D53F6A81-89F1-4FB3-86A9-8808006683C2 Online     3000248991744
- disk2s2   E58CA8F5-1D2C-423A-B4BE-FBAA80F85879 Spare      3000248991744
===============================================================================
In my situation with the failed RAID, I had an extra disk in this with the status of Missing/Failed.
The command is "diskutil appleRAID remove" and the cryptic help paragraph says:
Usage: diskutil appleRAID remove MemberDeviceName|MemberUUID
        RAIDSetVolumePath|RAIDSetDeviceName|RAIDSetUUID
MemberDeviceName|MemberUUID is the number listed in the "diskutil appleRAID List" command, and
RAIDSetVolumePath|RAIDSetDeviceName|RAIDSetUUID is the Device Node for the RAID which here is /dev/disk4.
I used this command to remove the third entry (missing/failed), I did not copy the terminal window text on that one, so I cannot show the list of three disks.
I could not get to remove the disk2s2 disk listed as SPARE, as it gave an error message:
Michaels-iMac:~ mike_aronis$ diskutil appleraid remove E58CA8F5-1D2C-423A-B4BE-FBAA80F85879 /dev/disk4
Started RAID operation on disk4 LaCie RAID 3TB
Removing disk from RAID
Changing the disk type
Can't resize the file system on the disk "disk2s2"
Error: -69827: The partition cannot be resized
But I was able to remove it using the graphical interface Disk Utility program using the delete key.
I then rebuilt the RAID set by dragging the second drive back into the RAID set.
I could not get the command: "diskutil appleRAID update AutoRebuild 1 /dev/disk4" to work, because even though it was trying to execute it HUNG. I put the two drives into my newer LaCie 2big as my attempt at further trouble shooting the RAID (this was not suggested by LaCie tech), rebuild the RAID and now I am going to leave it setup that way for a few days before I ship it back to just see if the old drives work fine in the new RAID box (thus proving the RAID box is the problem). I tried the AutoRebuild 1 command just now and it gave an error.
Michaels-iMac:~ mike_aronis$ diskutil appleraid update autorebuild 1 /dev/disk4
Error updating RAID: Couldn't modify RAID (-69848)
Michaels-iMac:~ mike_aronis$
In my haste to rebuild the RAID set for the third or forth time as LaCie led me through the testing this and test that phase, I forgot to click the "Auto Rebuild" option in the Disk Utility program.
Question for the more experienced:
As I was working on this issue, I notice that each time I rebooted and did work in the Terminal (with and without the RAID plugged in to the thunderbolt connection) I notice that the list of drives would change and my main boot drive would not stay listed as drive 0! Some times it would be drive 0, sometimes the RAID would be listed as Drive 0. It's strange to me...I would have thought the designation for Drive0 and Drive1 would always be my two build in drives (SSD and spinning drive).
Mike

Software RAID issue

I have just installed 2-200 GB seagate hd's into my machine and set them up as a software raid 0. Also installed is the original 80 GB drive and a Hitachi 160 GB drive. The two new drives functioned long enough for me to copy all of my raw digital home video.
Now, when I try to boot the grey Apple screen comes up and the machine hangs. When I disconnect the drives, it boots right up.
I thought maybe my power supply was giving up the ghost until I reconnected them and successfully rebooted with Drive Genius 1.2. I rebuilt the raid set (maintaining all data) and rebooted into OSX successfully. Woohoo!
But not so fast. Next reboot started the same thing. And now Drive Genius has no effect.
I really dont wan't to lose the data on these drives. Is there a problem with the software raid in 10.4.7? Any ideas of other things to try? Help?!?!
Thanks,
Andy
G4 1.25DP FW800 Mac OS X (10.4.7)
G4 1.25DP FW800 Mac OS X (10.4.7)

Possibly a couple things that "aren't quite right" with your setup.
SoftRAID 3.5 supports mirror for boot drive, but not with stripped.
The two IDE buses are not identical, making for some slight problems with RAID on the two.
You really can't RAID if both drives are together in one drive cage on the same IDE bus.
You need a PCI controller to RAID in MDD. Most people at this point in time opt for Serial ATA drives and controller. If you want a bootable SATA drive...
http://www.firmtek.com/seritek
If you must boot from stripped RAID (not always a good idea and may not offer much actually in real world performance, check www.barefeats.com for some tests for one).
A dedicated boot drive for OS/Apps and use other drives for media, data, scratch, even for /users.
Two ATA drives on the same bus, have to share the bus, contend for I/O.
You can create a stripe raid with Disk Utility and boot.
I assume that you read the SoftRAID QuickStart and Manual which really are helpful. There are a number of sites etc that can go into more about RAID.

Mac OS X 10.4 - Software RAID 10???

Hello All...
As a motion graphics artist by trade and a musician at night, I am constantly faced with the on-going dilemma of my storage needs. As you may probably already know, these two activities eat up drive space and require a speedy storage solution as well.
Here's my current setup:
- PowerMac G5 Dual 2GHz (PCI-X) w/ 3GB of RAM.
- Sonnet Tempo-X eSATA 4x4 PCI-X card.
- MacGurus Burly 4 bay SATA enclosure.
- 2 250GB WD drives in the Burly enclosure.
I have the two 250GB WD drives in the external SATA enclosure software-RAIDed together to form one RAID 0 (striped) volume, using the OS X disk utility RAID feature. While that has resulted in an excellent, fast, big disk... I am starting to run into errors, and starting to lose sleep over the fact that the current setup is not redundant / reliable.
My initial solution was to buy two more disks, RAID them together as another striped volume and run backups from the first two-disk WD striped volume to the new striped RAID. So, four disks, two striped raids with two disks each.... But when I called Sonnet Tech Support, the support guy said that OS X 10.4 has support for RAID 10. That changes everything! If I could fill the Burly enclosure with 4 of the same disks and software RAID 10 them together, I'd be in business... I think...
Does OS X 10.4 really allow you to create a software RAID 10???
If so, do you think this is the most ideal solution for what I'm working with?
Keep in mind, I'm working with a low budget. No, XServes/XServe-RAID is NOT an option!
Any input is greatly appreciated!
TIA

Hi, noka.
Yes, it supports RAID 10. See "Disk Utility 10.5 Help: Protecting your data against hardware failure with a mirrored RAID set."
However, you may not get the performance you expect.
FWIW and IMO, unless one is running a high-volume transaction server with a 99.999% ("Five Nines") availability requirement, RAID is overkill. For example, unless you're running a bank, a brokerage, or a major e-commerce site, you're probably spending sums of time and money with RAID that could be applied elsewhere.
RAID is high on the "geek chic" scale, low on the practicality scale, and very high on the "complex to troubleshoot" scale when problems arise. The average user, even one in your lines of business, is better served by implementing a comprehensive Backup and Recovery solution and using it regularly.
Good luck!
Dr. Smoke
Author: Troubleshooting Mac® OS X
Note: The information provided in the link(s) above is freely available. However, because I own The X Lab™, a commercial Web site to which some of these links point, the Apple Discussions Terms of Use require I include the following disclosure statement with this post:
I may receive some form of compensation, financial or otherwise, from my recommendation or link.

Can I install Snow Leopard and boot from software RAID 1 (mirror)?

I have a Mac Pro (quad core 2.66 GHz) on order for my office workstation. Yeah, I know new ones are probably coming out early next year but due to budget and upcoming projects I need one now. What I'd like to do is replace the pre-installed 640GB drive with two 1 TB drives and mirror them. The 640GB drive will be redeployed to another machine in the office. Can I boot from the Snow Leopard install DVD, go to Disk Utility, setup a RAID 1 with the two drives, install Snow Leopard to the mirror and then boot off the mirror set?
I've searched and found offhand comments to the effect that installing to and booting from a software mirror is OK, but I'd like to know for sure that it's OK. Any experience that you have with such a configuration would be nice to hear.

Yes. But before you do read the following:
RAID Basics
For basic definitions and discussion of what a RAID is and the different types of RAIDs see RAIDs. Additional discussions plus advantages and disadvantages of RAIDs and different RAID arrays see:
RAID Tutorial;
RAID Array and Server: Hardware and Service Comparison>.
Hardware or Software RAID?
RAID Hardware Vs RAID Software - What is your best option?
RAID is a method of combining multiple disk drives into a single entity in order to improve the overall performance and reliability of your system. The different options for combining the disks are referred to as RAID levels. There are several different levels of RAID available depending on the needs of your system. One of the options available to you is whether you should use a Hardware RAID solution or a Software RAID solution.
RAID Hardware is always a disk controller to which you can cable up the disk drives. RAID Software is a set of kernel modules coupled together with management utilities that implement RAID in Software and require no additional hardware.
Pros and cons
Software RAID is more flexible than Hardware RAID. Software RAID is also considerably less expensive. On the other hand, a Software RAID system requires more CPU cycles and power to run well than a comparable Hardware RAID System. Also, because Software RAID operates on a partition by partition basis where a number of individual disk partitions are grouped together as opposed to Hardware RAID systems which generally group together entire disk drives, Software RAID tends be slightly more complicated to run. This is because it has more available configurations and options. An added benefit to the slightly more expensive Hardware RAID solution is that many Hardware RAID systems incorporate features that are specialized for optimizing the performance of your system.
For more detailed information on the differences between Software RAID and Hardware RAID you may want to read: Hardware RAID vs. Software RAID: Which Implementation is Best for my Application?

Migrating Software RAID 1 ?!

Hello all, i just installed my new SSD on which i'm doing a fresh install of my OS, although have now run into an issue with regaining the software raid 1 i had setup on 2 external drives with the old OS. Can i possibly migrate this raid 1 to the fresh OS??the drives are not coming up at all at the moment but if i boot the old OS disk they appear as normal.
any help would be great
thanks

Did a bit more research, SCSI and storage use to be my hobby, and Mac Pro my passion. So I tried to dig into this further. SSD is very popular and people want to have 2 x SSDs along with 3-4 traditional mechanical hard drives. I just don't see going with an external type solution.
Short answer: ain't gonna boot.
You want a mirror - that should be fine.
I was not familiar at all with one item, but I advise people to not put USB/FW cases on SATA controllers, too many problems and issues.
*Raidon 4bay 19in 1ru esata enclusure*
Like this?
http://eshop.macsales.com/item/Raidon/SR4WBS2/
Is the controller one of the very few that are bootable? most are not.
To be bootable, the card would have to have Mac EFI firmware. Also, the EFI ROM version can "interfere" with support for cards and being bootable.
There are always drivers and firmware when it comes to booting. It is suppose to be "driver-less." translation: built into OS X 10.5.x and later.
NewerTech use Marvell chipset. I can say their 6G chipset which you can google and see who else uses them. I just picked up Marvell based 6G 2-port. So interested in why MINE is having trouble (conflicts with Sonnet Silicon Image most likely). I have a couple Sonnet cards, E4P and E2P, and there are drivers.
the Caldigit Fasta-2E is not bootable with the Mac Pro. In addition, while most FirmTek controllers are bootable with the PowerMac G4 and G5, they are not bootable with the Apple Mac Pro. Bootable External drives Mac Pro?
*NewerTech MAXPower eSATA 6G*
+Does NOT support booting on any Macintosh platform.+
http://eshop.macsales.com/item/Newer%20Technology/MXPCIE6GS2/
Or this one,
*eSATA 6G PCIe 2.0 RAID Capable Controller Card*
http://eshop.macsales.com/item/Newer%20Technology/MXPCIE6GRS/
http://www.newertech.com/products/pcieraidesata.php
Reviewed here (and this should be req'd site to check also for Mac Pro owners)
http://macperformanceguide.com/Reviews-MAXPowereSATA6G.html
http://www.xlr8yourmac.com/IDE/NewerTech6GeSATA/Newertech6GeSataCard.html
There is also FirmTek.
http://firmtek.com/seritek/seritek-2me4-e/perform/
http://eshop.macsales.com/item/Firmtek/SATAE6G/
Highpoint has always depended on driver.
Popular kit to install two SSDs in optical drive bay:
http://eshop.macsales.com/item/Other%20World%20Computing/MM352A52MP9/
External dual drive (SATA only, which is what I use and want for native SATA speeds)
http://eshop.macsales.com/item/Other%20World%20Computing/MESATATBEK/?APC=XLR8You rMac09
The ideal would be to boot off the two SSDs, and yes it would help to have a PCIe with internal ports, then use them in stripe RAID, not mirror (you can backup the OS and have a clone on external FW800; on sparse disk image of 100GB; on a small internal drive even), and when it changes.
http://www.xlr8yourmac.com/IDE/SSDin_Mac_Pro/SSD_install_inMacPro.htm#storytop
For an internal controller, HPT RR640 IF it was supported at all on Mac
http://www.newegg.com/Product/Product.aspx?Item=N82E16816115077
http://www.tweaktown.com/reviews/3309/highpointrocketraid_640_sata_6gb_s_4_port_pci_e_2_0controller/index.html
http://www.bit-tech.net/hardware/2011/01/04/high-point-rocketraid-640-review/5
To boot in 64-bit mode, all drivers and even some application plug-ins I believe have to be 64-bit, but not everything is 64-bit mode compatible.
one SSD in optical drive bay for system
no need to mirror
no controller
use the 2nd for scratch or an expensive off line backup
If the SSD fails, swap out, use clone, rebuild and restore.
No meed for mirror, AND disks writes are where SSDs can suffer and slow down.
But DO consider SoftRAID 4.x, great support for SSDs and driver even for non-RAID, but their mirror RAID is a notch above.
http://www.softraid.com
I found Highpoint RR Quad on Apple Store:
Is this compatible with the new 2010 Mac Pros? bootable?
http://store.apple.com/us/product/H1113LL/A#compatibility
I think you would get more mac pro owners to read and help in Mac Pro forum. And don't forget to stop by and check XLR8YOURMAC web site for news and tips about hardware upgrades and reports.

How to install on a software raid with dmraid?

In linux 2.4 the ATARAID kernel framework provided support for Fake Raid (software RAID assisted by the BIOS). For linux 2.6 the device-mapper framework can do, among other nice things like LVM and EVMS, the same kind of work as ATARAID in 2.4. While the new code handling the RAID's I/O still runs in the kernel, device-mapper stuff is generally configured by a userspace application. It was clear that when using the device-mapper for RAID, detection would go to userspace.
Heinz Maulshagen created the dmraid tool to detect RAID sets and create mappings for them. The controllers supported are (mostly cheap) Fake-RAID IDE / SATA controllers which have BIOS functions on it. Most common ones are: Promise Fasttrack controllers as well as HPT 37x, Intel, VIA and LSI. Also serial ata RAID controllers like Silicon Image Medley and Nvidia Nforce are supported by the program.
I would like to ask if someone out there managed to set up a raid machine with dmraid, and I am asking for a full raid setup, nothing like raid for /home only.

Loosec;
I see that you have a handle on the dmraid package, recently upgraded I see.
I have an application for raid that does not involve booting with raid, data system only.
I desire to generate an archive for pacman using a raid array for purposes of install speed.
My first attempts used mdadm techniques and provided a software raid of hde and hdg drives which did not produce an improved hdparm read speed.
What changes to dmraid procedures will provide a non-bootable raid0 system which will archive pacman packages and provide combined raid read speed at least 50% greater than the normal 40MB/sec.?
Performance figures for raid0 with dmraid haven't been available in the forums. Perhaps these are disappointing?
Basically, how to make a raid0 system with dmraid but not make it bootable?
EDIT: Solved my problem with mdadm and mke2fs, fstab entry and /mnt/md entry.
Last edited by lilsirecho (2008-03-14 07:50:00)

Software Raid Inconsistent on a mac pro

My software raid 0 array is sometimes slow, sometimes fast. Using the Blackmagic disk speed test utility, it sometimes gets 97MB/s read speed, and sometimes 150MB/s read speed. I ensure nothing else is running in the background between tests. Another test I do is to duplicate a folder containing 1 gig of files. Sometimes it takes twice as long to duplicate it. Early 2008 Mac Pro, 8 cores, 8 gig mem, raid 0 is two 750gig Caviars (using the 4th internal bay for time machine) Disk utility reports all is clean. Lion 10.7.1. Rebuild array? ideas?

Mac OS X runs with main memory massively over-committed. Because of this, it often has to return to the Boot Drive to get a few pages of this or that. This activity moves the read/write heads ways from the data area on the data drive and kills RAID performance.
If you have not done so already, you should consider creating a separate Boot Drive containing System, Library, Applications, and the hidden unix files including Paging/Swap. Move all User files off that drive, except one Admin User used only for Administration, not daily work.

Is it true any Mac Pro can do software RAID 0?

I dont know why I never came across this, but is it true that any Mac Pro (or just macs in general??) can do software RAID 0 if you have two of the identical hard drives? Basically the OS handles everything and no special hardware or card is needed?
If true, what would be the reason so little people do it for faster disk access??

RAID Basics
For basic definitions and discussion of what a RAID is and the different types of RAIDs see RAIDs. Additional discussions plus advantages and disadvantages of RAIDs and different RAID arrays see:
RAID Tutorial;
RAID Array and Server: Hardware and Service Comparison>.
Hardware or Software RAID?
RAID Hardware Vs RAID Software - What is your best option?
RAID is a method of combining multiple disk drives into a single entity in order to improve the overall performance and reliability of your system. The different options for combining the disks are referred to as RAID levels. There are several different levels of RAID available depending on the needs of your system. One of the options available to you is whether you should use a Hardware RAID solution or a Software RAID solution.
RAID Hardware is always a disk controller to which you can cable up the disk drives. RAID Software is a set of kernel modules coupled together with management utilities that implement RAID in Software and require no additional hardware.
Pros and cons
Software RAID is more flexible than Hardware RAID. Software RAID is also considerably less expensive. On the other hand, a Software RAID system requires more CPU cycles and power to run well than a comparable Hardware RAID System. Also, because Software RAID operates on a partition by partition basis where a number of individual disk partitions are grouped together as opposed to Hardware RAID systems which generally group together entire disk drives, Software RAID tends be slightly more complicated to run. This is because it has more available configurations and options. An added benefit to the slightly more expensive Hardware RAID solution is that many Hardware RAID systems incorporate features that are specialized for optimizing the performance of your system.
For more detailed information on the differences between Software RAID and Hardware RAID you may want to read: Hardware RAID vs. Software RAID: Which Implementation is Best for my Application?

Reinstalling OS X - losing software RAID?

We have a Xserve G5 with a 80GB hard drive + two 250 GB hard drives. The two 250 GB hard drives make up a mirrored RAID, configured using Disk Utility.
I'm going to upgrade the server from Tiger to Leopard, and I plan to perform a clean install on the 80 GB hard drive where the OS is now.
The Xserve does not have a hardware RAID solution.
If I do this, nothing will happen to the RAID, and the RAID configuration and data will still be there once Leopard Server is up and running, right?
Audun

Thank you for your reply.
I'll be sure to make a backup, but I'm still wondering about what will happen to the RAID.
My hunch is that the answer is "nothing", but that the ACLs might be screwed up because the users and groups will not necessarily exist after the reinstall. What I care most about is not having to copy files back from the backup as it would save me some time.
Even though this is a software raid, I'm guessing that Disk Utility saves the RAID info to some chip on the Xserve so that the information is available to OS X after the reinstall.

Adding second HD - software RAID?

I need to add a large drive (250 GB) to my MDD G4 running 10.4.6. The machine has one factory installed 76GB IBM drive. Will I need a new controller card? Will I need to set the new drive as a slave? If using the on board controller is limiting I might install a SATA or RAID controller.
Regarding RAID performance, does a RAID controller offer better RAID performance than the OS X software implementation?
Any insights appreciated.

Thanks. I have an ACARD ATA 133 raid card which I was thinking of using. Your comments on the performance of the on board controller seem to indicate that the card will increase performance. Are problems with data common with raid 0?
I need to add a large drive (250 GB) to my MDD G4
running 10.4.6. The machine has one factory
installed
76GB IBM drive. Will I need a new controller card?
Will I need to set the new drive as a slave? If
using
the on board controller is limiting I might install
a
SATA or RAID controller.
Regarding RAID performance, does a RAID controller
offer better RAID performance than the OS X
software
implementation?
Any insights appreciated.
Depends.
On my machine, a 200gb 7200rpm ATA 133 drive
connected to a Sonnet (non-raid) controller
outperforms an 80x2 raid drive on either the the
secondary bus on the Sonnet or the ata100 connector
on the motherboard.
This was also true on my older single 867.
At work, on a dual 1ghz MDD, the oem 80/ata100
outperforms a 30x2 raid on the ata66 bus.
I would recommend building your raid with 2 identical
drives. Using mixed size or speed drives will result
in both wasted space, and, if the block sizes are
different, potential data problems.
The 200gb drive is faster on the Sonnet card than on
the motherboard.
Keep in mind that if you need to boot directly to OS9
for whatever reason, it will not recognize the raid
or the 250gb drive.
For that reason, I have a 30gb drive dedicated for
OS9 and it's applications

Server 10.5 on PPC with software RAID not bootable?

I read in this article (http://docs.info.apple.com/article.html?path=ServerAdmin/10.5/en/c5sa15.html) that "No PPC-based Macs support booting from software RAID volumes."
I believe that this is not true! From my software dealer i was told there should be no problems to do this. I called Apple and the guy i spoke with also told me that it works fine. I actually now have set up a software RAID1 (PPC G5 2.3Ghz, 2x500GB HD) from wich i boot and it does work!
My question is: Are there any risks to continue running this installation?
/Andreas

One risk is you can't partition an Apple software RAID 1 in Boot and Data volumes so you could potentially have either overwrite "the other". An "overfull" share can damage the system and vice versa.
And write performance can suffer because writes aren't simultaneous (?).
Another risk is the server woun't tell you when one disk fails so if you don't notice when the other one also fails the data on the first one is old (backups are essential as usual). Or if thinking "there is a "failover" disk available" when it too already have failed a while ago (but ofcourse no worse than having only 1 drive and no mirror).
Depending on the cause of failiure, software/glitch or mechanical, the disks can be in different "shape" if you have to try restoring the data.
A good idéa is have an extra drive (firewire?) you backup (one way synch replacing/removing old files/removed files) to every night.

Software raid won't boot after updating to "mdadm" in mkinitcpio.conf

After a power outage I've discovetred the config I was using (with raid in mkinitcpio.conf) no longer works, it's mdadm now - that's fine. I've updated that and re-run mkinitcpio successfully, however my system is unable to boot from the root filesystem /dev/md2 like so:
Waiting for 10 seconds for device /dev/md2 ...
Root device '/dev/md2' doesn't exist. Attempting to create it.
ERROR: Unable to determine major/minor number of root device '/dev/md2'.
You are being dropped to a recovery shell
Type 'exit' to try and continue booting
/bin/sh: can't access tty; job control turned off
[ramfs /]#
As far as I can see from reading various threads and http://wiki.archlinux.org/index.php/Ins … AID_or_LVM I'm doing the right things now (although I'm not using lvm at all, which makes the installation document a little confusing).
I think I've included all the appropriate bits of config here that should be working. I assume I've missed something fundamental - any ideas?
menu.lst:
# (0) Arch Linux
title Arch Linux [/boot/vmlinuz26]
root (hd0,0)
kernel /vmlinuz26 root=/dev/md2 ro
initrd /kernel26.img
mkinitcpio.conf:
HOOKS="base udev autodetect pata scsi mdadm sata filesystems"
fstab:
/dev/md1 /boot ext3 defaults 0 1
/dev/md2 / ext3 defaults 0 1
mdadm.conf
ARRAY /dev/md1 level=raid1 num-devices=2 metadata=0.90 UUID=7ae70fa6:9f54ba0a:21
47a9fe:d45dbc0c
ARRAY /dev/md2 level=raid1 num-devices=2 metadata=0.90 UUID=20560268:8a089af7:e6
043406:dbdabe38
Thanks!

Hi magec, that's quite helfpul - I've certainly got further.
Before I was doing this to set up the chroot (which is what is suggested in the wiki article about setting up software raid):
mdadm -A /dev/md1 /dev/sda1 /dev/sdb1
mdadm -A /dev/md2 /dev/sda2 /dev/sdb2
mount /dev/md2 /mnt
mount /dev/md1 /mnt/boot
mount -o bind /dev /mnt/dev
mount -t proc none /mnt/proc
chroot /mnt /bin/bash
But based on your suggestion it's working better
mdadm -A /dev/md1 /dev/sda1 /dev/sdb1
mdadm -A /dev/md2 /dev/sda2 /dev/sdb2
mount /dev/md2 /mnt
mount /dev/md1 /mnt/boot
mount -t proc none /mnt/proc
mount -t sysfs none /mnt/sys
mount -n -t ramfs none /mnt/dev
cp -Rp /dev/* /mnt/dev
chroot /mnt /bin/bash
The boot is now getting further, but now I'm getting:
md: md2 stopped.
md: bind<sdb2>
md: bind<sda2>
raid1: raid set md2 active with 2 out of 2 mirrors
md2: detected capacity change from 0 to 32218349568
mdadm: /dev/md2 has been started with 2 drives.
md2: Waiting 10 seconds for device /dev/md2 ...
unknown partition table
mount: mounting /dev/md2 on /new_root failed: No such device
ERROR: Failed to mount the real root device.
Bailing out, you are on your own. Good luck.
/bin/sh: can't access tty; job contol turned off
[ramfs /]#
The bit that really confuses me is this:
[ramfs /]# cat /proc/mdstat
Personalities : [raid1]
md2 : active raid1 sda2[0] sdb2[1]
31463232 blocks [2/2] [UU]
md1 : active raid1 sda1[0] sdb1[1]
208704 blocks [2/2] [UU]
unused devices: <none>
[ramfs /]# mount /dev/md2 /new_root
mount: mounting /dev/md2 on /new_root failed: No such file or directory
[ramfs /]# ls /dev/md2
/dev/md2
[ramfs /]#
So the array is up, the device node is there but it can't be mounted? Very strange.
Last edited by chas (2010-05-02 11:24:09)

Can you move a software raid 1 from one mac to another

I have a 2 disc software raid 1 on my powermac and I want to move it to my mac pro. Does anyone know if I can do this?

It appears that in Mac OS X 10.4, and again in the transition to 10.7, RAID format may have undergone dramatic changes. If you are trying to move a RAID array across those boundaries, you may not have the best results moving the drives directly.

Software Raid 5 - Performance

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