Little software mirror raid configuration question

Setting up a Boot volume mirror RAID of two internal drives with Disk Utility -- any suggestions as to whether to check "RAID Mirror AutoRebuild" or not?
I understand the concept, but in practice am wondering, if I leave it unchecked, will I be notified if one of the drives fails? Don't really want to be having to manually check periodically if both are still running okay...
Thanks!

Thanks so much for thoughts and that great software pointer. I bought two of the same make/model drives with this mirror in mind so I should be cool there.
Yeah, I know your backup advice is very sound -- and I'm absolutely still chewing on whether I want to put my eggs in Mirror RAID or Super Duper. I understand the pro/cons of each, but I also just know that I'm not going to do both -- I'm just not that high maintenance/big spender.
I was edging towards mirror just because, in 3 years of doing regular clone backups I've never happened to have the need to restore yesterday's system due to a bum software update or the like, but I have had drives fail on me and lose the last two days of intensive work... I like that with Mirror there's no thought.

Similar Messages

Mirrored RAID Set Questions

I initially set up a mirrored RAID set up on my system drive as a means of backing up my files. I've since decided I'd like to use Time Machine instead. When I try and break up the RAID set using Disk Utility, a lock icon appears next to the RAID set and I'm unable to "delete" the set. My guess is that I need to reboot off a different system, but since Lion didn't come with an install disc, and since Lion doesn't set up a Recovery HD on RAID sets, how would I go about unlinking this mirrored RAID set?
Conversely, I inadvertantly unlinked a different RAID set and would like to reconnect them, but Disk Utility says it'll erase all the data on the drives before it establishes the connection. Is there a way to reconnect a mirrored RAID set that has been disconnected?

For the first question, go back to the App Store download Lion again but before it begins the install stop the process and create a flash drive installer. See How to make a bootable Lion install disc or drive .
Remember you have to make sure the install process doesn;t proceed because once Lion is installed the installer app will be removed from your HD.
Sorry can;t help with the second question.
regards

Mirrored Raid as boot disk?

I have a flat panel iMac (PPC) that I would like to have a bit more reliable. Due to the number of files I have on this machine, it is currently configured to boot from an external Firewire drive. Recently, I have added a second external firewire drive of the same size, and am considering a Mirrored raid configuration for this system. I am primarily interested in reliability, not increasing the performance of the system, hence the mirrored, rather than stripped, raid configuration.
It is clear from other postings on the web that a stripped raid requires a) reformatting the drives, losing all data, and b) cannot be used as a boot drive, which is mandatory in this case.
Therefore my questions:
1) Can I create a mirrored RAID using Disk Utility without data loss? One drive is newly formatted, the other is full of data.
2) Can this RAID be used to boot an early flat panel iMac?

Hi Eric Hildum;
1) No.
2) Probably yes. Practically no because it is going to cause you more problems then it is worth running both disk ins a RAID over a single Firewire channel.
Don't forget that Raid is not a valid backup solution. Any data on the RAID array should also be backed up for it's protection.
Personally for the home user, I think a good backup solution beats RAID. Usually there are less problems with backup then RAID.
Allan

Mirrored RAID set has degraded following power outage.

Hello,
Following a recent power outage our Mac Pro running Leopard OSX Server with 2 x 1TB discs in a Mirroring RAID configuration (with an installed RAID card) developed a 'severe error' message.
The Raid Set R0-1 has a Viable (degraded) status.
Drive One (or bay 1) is 'Good' and 'Assigned'
Drive Two is 'Good' but with the State - 'Roaming'
Also, the events display describes the failure of a drive 3 (there isn't one) and that the R0-1 is Degraded and no spare is available.
So, we're a little confused.
1. Is the Drive 2 no longer part of the RAID mirror (i.e. Roaming)
OR
2. Something more significant has happened hence the bogus Drive 3 message?
Any suggestions or advice would be much appreciated as always.
Thanks
Steve

Yes. Verification with the GUI tool is the first step. But... hmm, if you are dropping communications with the card, that is not a good sign. Make sure you have a backup and then try a PMU reset on the system. Maybe there is something wacky in the power manager. Then try any/all of these from Terminal to get more information:
raidutil list status
raidutil list eventinfo
raidutil list raidsetinfo
This should provide feedback. If these commands fail, then I fear that the card is not responding. Do you have AppleCare? It might be time to call for a replacement card.
Hope this helps

CalDigit RAID-Card Questions

Hey all,
I'm going to be upgrading my Mac Pro setup soon, as I'm in desperate need of more high-speed hard drive space. The CalDigit RAID-Card seems like a great product, with expandability in mind, as well as some other great features.
I'm planning on doing a RAID 5 setup with all four drives (as the CalDigit RAID-Card allows you to make a RAID set bootable). Now, I've been told time and time again to not make your Scratch Drive the same as the System Drive (advice which I've always followed). However, if all four drives were RAID'ed together via RAID 5, and then, two partitions were made (1.0 GB for the system, and 3.0 GBs for the Scratch Disk), does this solve the inherent risks / performance problems associated with making a Scratch Disk the same as the System Boot Drive?
Does having the System Software on a Bootable Hardware RAID get rid of the risks via RAID'ing via software?
Or, should I just RAID 5 three of the drives, and leave one for the System all by itself? Obviously, with 4 TBs of drive space, I'm trying to maximize that amount of storage I can get internally. Thanks!

I believe their RAID card is a software RAID card, & software RAID is definitely not recommended.
Dear Jon,
When it comes to striped RAID sets, I have not found a single hardware RAID setup that can out perform a Disk Utility software based RAID configuration. When it comes to RAID 5/6 - Intel IOP based hardware RAID cards provide superior performance. In addition, the Intel IOP hardware design usually dictates that all cards with the same processor will provide RAID 6 performance that is similar regardless of the manufacturer.
Saying that software RAID is not recommended really is too little information and untrue in many configurations. Hardware RAIDs carry their own problems. When a hardware RAID card fails the user needs a replacement card that is usually more expensive to obtain, requires additional down time and may not be available at all if the company has ended the life of the product.

Mirrored RAID Question

Possibly a dumb question: If Mac OSX (10.4.11 in this case) boots from a mirrored RAID (2 drives), is there any additional protection from routine disk directory errors? Again, I'm not asking about the physical failure of one of the drives, but from the type of directory errors that sometimes happen after a system freeze or loss of AC power to the system.
Another way of asking the same question: Will disk directory errors in one drive be automatically mirrored in the second drive, or will the second drive not have the same directory errors?
Background: I've got an older G4 tower with two identical drives installed that I use as a play/experiment computer. I can either keep the two drives totally independent and do daily (or even more often) total, bootable backups from the primary to the backup drive, or else configure as a mirrored RAID.
Thanks.

Both drives should be on independent bus or using a controller. The MDD has two buses, but ATA/66 and ATA/100 differ by 4% and enough difference to not recommend using two drives in any form of stripped or mirrored RAID.
Two drives on same bus, master/slave I would avoid as the bus has to wait for one drive for I/O before it can talk to the second drive.
With an SATA no such problem or limitation, or using an ATA controller with two independent channels.

Software mirrored disk raid crashes Mac.

I had two 1TB disks mirrored raid on a Mac Pro (software raid). Took them out and sold the computer. When I connect either one externally to my new iMac they crash my computer. Please help!

What brand and connection type of enclosure ?

Which RAID Configuration for my WD "My Book Mirror Edition"?

About to reformat my WD "My Book Mirror Edition" to use on my iMac. I hope to also install on my iMac "Virtual Box", "VM Fusion", or "Parallels" and then run a few windows products. Which RAID configuration should I choose in the WD "drive configurations" box?

If I were you I'd run any Virtual Machine directly on your iMac, not on a "WD My Book Mirror Edition", in particular not when connected through USB 2.0.
To store data, the WD is fine.
For the RAID options:
RAID 0 ("striping") : if you want something fast (insofar this is possible with a USB connection). Note that when one of your disks fails you can say goodbye to all your data.
RAID 1 ("mirroring"): more safe. If one disk fails, the data are recoverable as they are on the other disk as well. Disadvantage is you get only half the storage capacity compared to RAID 0.
Oh. my personal recommendation: RAID 1 is not an alternative to making a backup. So whatever option you choose: if you store valuable data on the disk that are nowehere else: back them up!
On formats:
HFS+ : definitely recommended if you only use the RAID array on the Mac.
FAT 32: if you also use it on a Windows machine. Note that files cannot be larger than 4 GB in this case.
Hope this helps.
Eric

Possibly boneheaded question re mirrored raid

Hi, if half of a mirrored raid set up with disk utility fails does the volume stay mounted and usable? Or is there still some sort of recovery necessary?
I'm thinking yes that's the point but I thought I'd better ask.
Thanks,
Dave

Both drives should be on independent bus or using a controller. The MDD has two buses, but ATA/66 and ATA/100 differ by 4% and enough difference to not recommend using two drives in any form of stripped or mirrored RAID.
Two drives on same bus, master/slave I would avoid as the bus has to wait for one drive for I/O before it can talk to the second drive.
With an SATA no such problem or limitation, or using an ATA controller with two independent channels.

What is the best RAID configuration for a MacPro as a Logic User?

There ought to be a universal answer to this question: what is the best RAID configuration for Logic Mac Pro users? I will be more specific.
I use Logic Studio, Reason, Ableton, and Motu Symphonic Instrument simultaneously.
I want to fail safe my precious audio files and improve performance as the system reads/writes data from multiple files, from audio tracks to digital samples.
I want to run video files simultaneously to do nifty audio soundtracking to video.
Here is the configuration I have in mind.
HD 1: OS and Logic Studio, Reason/Ableton samples etc. software (non-raid) (250 GB)
HD 2/3: MIrrored RAID set for AUDIO FILES (500 Gb identical pair)
HD 4: Video files / Bouncing (1 TB)
Makes sense right? A disk for reading software. A pair of 500 GB disks for reading/writing audio files and sessions in mirrored array. A 1 TB disk for video and bouncing. The main question I have is, for audio files only, is striped or mirrored better? 64K blocks the best? And are there any more details. I assume to do this in Disk Utility.

Well, both Mirrored and Striped have their pros and cons. If you use mirrored, it will offer no better performance than the spec'ed drive along with it's sata bus speed. The plus point is, if one drive goes down, you have the second as a backup as the complete contents of one drive are mirrored on the other.
With striped you will get a performance boost because all files (for example a single project) will get written across both drives and hence split the load on the drives and the SATA busses. The drawback is that you'll have to make sure you have a good, regular backup schedule in place because when one of the drives goes to drive heaven, you're going to be stuffed without a full backup of both drives.
Exactly what performance boost you'd get will depend on your project, number of files, size of files, fragmentation of files, track count etc. You may find it would be easier to use the 3 drives straight, with no raid and have:
HD 1: OS and Apps. No samples at all.
HD2: Audio Files for Logic projects
HD3: Reason, Ableton, Logic etc instrument sample library
HD4: Video and bouncing.
Which is what I ended up doing although I use HD4 as an interchangeable backup for HD1 and 2.
There is no universal answer to this as each must make their own choice based on their preferences and needs. Mirrored will give you full backup but on-site, in machine backup. Not much good if something untoward and drastic happens to the physical machine. I think a few people toy with striped RAID but fall on the side of using the drives straight, as in their projects they don't see a big enough gain over splitting the data across your 3 remaining drives without RAID. Studios that seriously consider raid often go out and get a dedicated raid that can offer more variations than raid 0 or raid 1 (Striped and Mirrored) and better throughput.
I hope this helps a little and not just added to the dilemma.

Solaris 10 and Software Mirroring

Hey Folks,
I'm attempting to configure software mirroring on a Solaris 10 system. Because this system is a v440, I'm using the hardware mirroring for the OS.
The other two drives in the system I am using for a database, and so, will configure software raid on them. However, I've done the following:
(created slice 3 and 4 on each drive for metadbs)
prtvtoc /dev/rdsk/c1t2d0s2 | fmthard -s - /dev/rdsk/c1t3d0s2
metadb -af -c 2 /dev/dsk/c1t2d0s3 /dev/dsk/c1t2d0s4
metadb -af -c 2 /dev/dsk/c1t3d0s3 /dev/dsk/c1t3d0s4
# below is the only partition i need to mirror, which will hold the
# oracle db files
metainit -f d20 1 1 /dev/dsk/c1t2d0s0
metainit -f d30 1 1 /dev/dsk/c1t3d0s0
metainit d2 -m d20
metattach d2 d30
After running metattach, both drives syncronize, and appears to be fine. I can mount it, read/write etc..
As such, I updated vfstab with the following:
/dev/md/dsk/d2 /dev/md/rdsk/d2 /opt/app/oracle/oradata ufs 2 yes -
and a mount -a works..
On reboot, it seems like my mirror has disappeared:
Can't stat /dev/md/rdsk/d2
/dev/md/rdsk/d2: CAN'T CHECK FILE SYSTEM.
/dev/md/rdsk/d2: UNEXPECTED INCONSISTENCY; RUN fsck MANUALLY.
fsckall failed with exit code 1.
WARNING - Unable to repair one or more filesystems.
Run fsck manually (fsck filesystem...).
svc:/system/filesystem/local:default: WARNING: /sbin/mountall -l failed: exit status 32
Jun 27 08:18:30 svc.startd[7]: svc:/system/filesystem/local:default: Method "/lib/svc/method/fs-local" failed with exit status 95.
Jun 27 08:18:30 svc.startd[7]: system/filesystem/local:default failed fatally
You'll notice from my steps, I did not run metaroot. I cannot, since ths is not a root partition and metaroot gives an error.
Which brings me to my question, what have I missed? Why does software raid fall apart on reboot?

Hi!
I have found these two errors too.
The second one I`m still trying to solve, but, in order to solve the first one, please, check if the parameters of you vfstab are written in the same line, like this:
#device device mount FS fsck mount mount
#to mount to fsck point type pass at boot options
fd - /dev/fd      fd      -      no -
/proc - /proc      proc      -      no -
/dev/md/dsk/d2 -      -      swap - no -
/dev/md/dsk/d1 /dev/md/rdsk/d1 /      ufs 1 no -
/dev/md/dsk/d4 /dev/md/rdsk/d4 /etc/opt/OV ufs 2     yes -
/dev/md/dsk/d5 /dev/md/rdsk/d5 /opt/OV      ufs 2 yes     -
/dev/md/dsk/d3 /dev/md/rdsk/d3 /var/opt/OV ufs 2     yes -
If not, Solaris 10 does not recognize the parameters that are written in the line below. (Don`t ask me why).
Hope it helps,
Regards,
Thais

Fan Speeds, and Mirror Raid with New Internal Hard Drive

Regards,
I recently installed and formatted a new hard drive in my PowerMac dual 2.3 ghz computer and I have a few questions.
1. Now that there are two hard drives do I need to do anything to ensure that the fan on my computer can keep them cool? I think the fans I have in the hard drive bay is enough, but I do not know if they will automatically set themselves to run properly. I can monitor the fan speeds and temp from iStat pro, but do not remember what level the temperature was before installing the new one.
2. Given that my new drive is a SeaDisc hard drive and the older one is a Western Digital, will this cause any problems in creating a mirrored RAID. I believe that both are 7200rpm drives, and my second hard drive is a little larger (I will just have unused space after making the RAID). I am concerned with the fact that these two drives are from two different manufactures. Will this cause problems or drastically slow down the reading and writing of data? Has anyone else experienced problems in making a mirrored RAID from two hard drives that are not exact matches, and even come from different manufacturers?
Any advice will help.
Thanks
earpshmael

Hi earpshmael;
Generally when creating RAID arrays the more similar the drive the less problems you tend to have.
The real question is exactly why do you want or need RAID?
I think so many people seem to think that RAID will solve all of their problem. I hate to tell you the bad news but it will not.
Generally there are to varieties of RAID available using the software RAID built into OS X which are 0 and 1. RAID 0 or stripling is generally for moving large file rapidly for applications like HD video. It usually doesn't help the OS. RAID 1 or mirroring is for protection from drive failure. It is not a valid backup solution.
Allan

Possible to boot B&W G3 from mirrored RAID??

Hi all,
I've tried to get my B&W, running server 10.3.9, to boot from a mirrored RAID (RAID 1). So far, I can successfully create the RAID, run the software installer, and choose the RAID with Startup Disk, but upon restart, it doesn't recognize a valid system (flashing system folder/question mark).
There's a tech article that states the B&W G3 won't boot from a striped RAID (RAID 0), but I've not been able to find anything definitive regarding mirrored RAID. Does anyone know for sure (or know where I can find documentation)?
TIA,
Brad
B&W G3 Mac OS X (10.3.9) 10.3.9 server

Thanks for the info. I had no problem either creating the RAID (successfully in both Disk Utility and Terminal), installing the OS, or selecting the RAID pair as the startup disk. I'm doing this with ATA disks.
Once done, though, the system won't boot from the RAID pair. I know that the B&W open firmware won't allow startup from striped RAID (technical article http://docs.info.apple.com/article.html?artnum=58258 applies), but don't know if this applies to mirrored RAID as well.
Has anyone out there successfully booted a B&W G3 from a RAID 1 configuration?

VM Server installer does not recognize RAID configuration in Intel ESRT2

Hello,
I'm having a big issue here trying to deploy my third Oracle VM Server.
I have:
- A Intel Server Board S3420GPLC
- A Intel Xeon X3440 processor
- 16GB DDR3 ECC Memory
- Six 1TB Hard Drives
What I'm trying to do:
- Create a RAID array using Intel ESRT2 (Embedded Server RAID Technology II) using all the discs (done)
- Install Oracle VM Server into the array
- Install some VMs....
The problems:
- When I boot the VM Server installer from USB stick I got an error saying that there is not enought memory. This issue is solved by typing "linux mem=15GB"
- I got a screen per disk warning me about that the discs need to be initialized and all the data will be lost
- When I go to the disk partitioning screen all the disks are listed separated, the installer simply don't recognize the RAID configured before.
What I already tryied:
- Change the RAID controller from ESRT2 to Intel Matrix
-> Didn't solve.
- Create a Driver Disk with the disk images supplied by Intel here
-> I launch the installer using "linux mem=15GB noprobe=ata1 noprobe=ata2 ....". When Im asked by the installer to load the drivers it doesn't recognize the disk, so i couldn't load the drivers.
Now, the questions:
- Is there another driver I can use do make the vm server installer recognize the RAId configured?
- Is there a better way to setup this server, considering that it needs to be "self contanied" (store and run vms)?
Edited by: xyp on 14/10/2010 11:37

So...
- I have installed VM Server into ordinary linux partitions on the first disk.
- I have created a big partition in the first disc with the space not used for the VM Server
- I have created five equal partitions on the other discs
- I have configured software raid 10 using mdadm
Now the problem seems to be solved, i have a storage repository with almost 3TB and can deploy my VMs.
Unfortunatelly only my windows 2008 r2 hardware virtualized vm is working, the linux paravitualized guests not. but this new issue will be a subject for another topic.

Mirror RAID on partitioned drive

Can you Mirror a partitioned drive (boot plus data)? thanks

thats no problem reformatting just wondered if I had a boot partition and a data partition how does a mirror work - automatically on both partitions or do you create two mirrors one for each partition<</div>
I know on my "hardware" mirrored RAID, it all automatic. Any information or partitioning written to the "primary" drive is instantly "mirrored" to the "secondary" drive. Mirrored RAID drives are configured to be "exactly" identical, that's why you need matching drive capacities as well as manufacturer.
As for "software" RAIDs, I'm sure they are setup the same way, except the computer takes over the process of making sure the information is the same on both drives. On my HW RAID, I don't even need it connected to a computer to do a HD restore.
HTH

Little software mirror raid configuration question

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