XServe RAID RAID5 performance?

Hello,
I would like to know how the XServe RAID performs in RAID5.
We are using multiple FC and SCSI RAID-subsystems at work and we need a bigger one by the end of the year.
TIA
Best
Nicolas

The Xserve RAID is specifically tuned for RAID 5 performance -- RAID 5 is about 99% as fast as RAID 0. Unless you were hosting a database on the RAID, and doing lots of small I/Os, there is no reason to use any other RAID scheme on Xserve RAID
There's a performance page here:
http://www.apple.com/xserve/raid/performance.html
With some info... not very detailed. If you can get ahold of an eval unit (Apple's direct sales force has a program for this), you can run Iozone benchmarks on one, and see how it might fit your usage pattern.

Similar Messages

Proper procedure for replacing drive in Xserve RAID RAID5 set

I've got a five-drive RAID-5 set (with a sixth hot spare) in an Xserve RAID running the 1.5/1.50f firmware. One of the drives in the RAID-5 set has an amber/orange status light on and has been getting occasional errors like to following:
Timestamp: 11/10/10 10:34:53 AM
Priority: Warning
Controller: Upper Controller
Type: 112
Event ID: 1000
Event: Disk 5 Reported An Error. COMMAND:0x35 ERROR:0x10 STATUS:0x51 LBA:0x19B80
Description: The drive reported an ATA error. This is a failure in the communication from the RAID Controller to the drive.
I have double checked the drives in RAID Admin and, as the drive is only in a warning state, the hot spare has not been pulled into the RAID set yet. As this is an old drive, I'd like to replace that particular drive first. I have a current, full backup of the data, but want to make sure I understand the process correctly.
I understand the "Installing or Replacing an Apple Drive Module" section of http://manuals.info.apple.com/en/XserveRAID_UserGuide.PDF, but it and RAID Admin's built-in help don't describe what will happen when replacing a drive in a RAID set that has a hot spare. When I pull out the drive and replace it, will it correctly use the newly inserted drive or will it use the hot spare? If it uses the hot spare, will the hot spare revert back to a hot spare once the new drive is inserted or will it permanently become a member of the RAID set and need to be moved to the original drive's slot? Or, should I just pull out the hot spare, pull out the failing drive, and pop the hot spare into the failing drive's slot?

Hello, makkintosshu, and welcome to the AppleBoards,
If you pull out the drive the RAID should/will immediately start rebuilding using the hot spare. The hot spare will become a new permanent member of the RAID and the new replacement drive will become the new hot spare. The physical slot locations of the drives don't matter you can build a RAID from any combination of drives as long as they are on the same side.
If you pull the hot spare and then the failing drive the RAID will wait for a new drive before taking action. I find it hard to recommend this course of action unless there is a really good reason for you not wanting the hot spare to become part of the RAID. Rebuilding is going to take a good long while and you want it to start as soon as possible - as long as the RAID is not rebuilt your data is at risk. Letting the RAID rebuild hang as you physically swap out the failed the drive strikes me as bad idea that needs a really good justification.
HTH,
=Tod

Iozone website benchmark results on Xserve RAID

Hi,
I'd like to try and find out how the Apple RAID was configured for the
iozone benchmark. The results of the benchmark are here:
http://www.iozone.org/src/current/Xserver.xls
I asked the question directly to iozone and the answer was that the
benchmark was run in the Apple booth at some tradeshow/conference.
The booth guys let the iozone guys run the benchmark there.
The write results in the iozone benchmark are about 2.5 times better than
the write results we are getting so I'd like to try and figure out how it was
configured.
I'm going to be using the Apple RAID in an intensive write database
application running MySQL. Here's some info on my setup:
My system is a Sun v40 4xOpteron with 8Gig of RAM. I'm running
Solaris 10 release 03/05.
The apple RAID has all 14 disks and is fibre connected. The disks
are setup so that the mirroring is done in the Apple RAID. This produces
a bunch of LUNs. These are all striped together at the OS level, so
the setup is RAID 10. Note that this version of the OS only supports
a LUN size of 2TB max.
Thanks for any help,
Mike
Mac OS X (10.4.6) Xserve RAID

The last tab in the spreadsheet tells you how the RAID was configured, namely RAID 5 128 stripes.
From what I recall when I ran iozone against one of my XServe RAIDs, their figures came out a little higher than mine, but not dramatically. I'll see if I can find the data dumps for comparison.
In the meantime I would look at how you're configuring the RAID. publishing a series of mirrors and using striping at the host level seems less-than-ideal. You're forcing the XServe RAID to write the data twice on each controller, as well as requiring the OS to manage which LUNs it's writing to.
(remember, RAID 1 write performance is lower than other RAID levels)
You would be better off running either RAID 0+1 (striping on the XServe RAID with each side mirrored by the server), or RAID 5, leaving everything up to the XServe RAID - the XServe RAID's performance at RAID 5 is not significantly lower than RAID 0 and it eliminates any overhead on the server side.
If it wasn't for the volume size limitation in Solaris I would recommend RAID 50 over 10 (RAID 5 on the XServe RAID, striped on the host) but that would likely exceed the 2TB volume limit.
Other things to check are the write caches on the drive (use only if you're in a stable power environment).

How to connect multiple Xserve Raid for Best Performance

I like to get an idea how to connect multiple Xserve Raid to get the best performance for FCP to do multiple stream HD.

Again, for storage (and retrieval), FireWire 400 should be fast enough. If you are encoding video directly to the external drive, then FireWire 800 would probably be beneficial. But as long as the processing of the video is taking place on the fast internal SATA drive, and then you are storing files on the external drive, FireWire 400 should be fine.
Instead of speculating about whether it will work well or not, you need to set it up and try your typical work flow. That is the only way you will know for sure if performance is acceptable or not.
For Time Machine, you should use a single 1.5TB drive. It is likely that by the time your backup needs comes close to exceeding that space, you will be able to buy a 3TB (or larger) single drive for the same cost. Also, I would not trust a RAID where the interaction between the two drives is through two USB cables and a hub. If your primary storage drive fails, you need your backup to be something that is simple and reliable.
Oh, and there should be no problem with the adapter, if you already have it and it works.
Edit: If those two external drives came formatted for Windows, make sure you have use Disk Utility Partition tab to repartition and reformat the drive. When you select the drive in the Disk Utility sidebar, at the bottom of the screen +Partition Map Scheme+ should say *GUID Partition Table*. When you select the volume under the drive in the sidebar, Format should say *Mac OS Extended (Journaled)*.

Super Slow Performance with Xserve RAID / Promise Fibre

Hey guys,
I am experiencing a strange thing on both 10.5.8 and 10.7.5 servers (yes these are in the process of being retired). They are sharing out either an Xserve RAID or Promise Vtrak with OS X Server.
We have the fibre channel card and the storage attaches to there and they appear mounted on the desktop.
The problem we are having is that whenever OS X's file sharing is enabled these volumes run incredibly slow! I did a clean install of OS X 10.7.5 on an entirely different machine and it was still bad. All of my tests show that when you turn off file sharing, both AFP and SMB, the performance goes back to normal -- so what can we do here??? These are file servers, so that's pretty much the only thing that needs to work.
Thanks,
Andrew

Slow/poor RAID performance can be down to a number of things. Some of which are easier to check than others.
Some easy things to check are:
How much data is stored on the RAIDs?
Performance really drops off alarmingly once the RAID gets to 85% full. For a 1TB RAID this means you need to keep at least 250GB of free disk space at all times otherwise you will get the poor performance you're seeing. Once it gets to 86/87/88% full performance can drop alarmingly. Yes those few percent points can make a big difference.
How is the data stored on the RAIDs?
Having thousands and thousands of single files stored loosely on the RAID or within one single folder is not a good idea. The Finder can be and is fairly inefficient at drawing the icons for those files that are presented to network users accessing the share point(s). This can/and is perceived as very slow performance as you're viewing the files over a network connection. One way to overcome this 'feature' is to organise the data into logical folders/sub-folders and/or shares.
Are there problems with the file/directory structure of the RAIDs themselves?
Use DiskUtility (or better still DiskWarrior) to repair any issues (generally built up over a period of time) with the storage disks you have. You can't repair permissions using DiskUtility or anything else on a non-OS bearing drive. Don't forget to do this also for your System Drive (which can have its permissions repaired) as well. This will mean the server being off-line for a time whilst the system (OS) drive is being repaired. Before doing this step I would make sure you have a current and effective backup of your System/Server OS as well as all data stored on the RAIDs themselves. Hopefully you should be doing this for your data already?
To understand Disk Utility's repair permissions feature please read Apple's support document here:
About Disk Utility's Repair Disk Permissions feature - Apple Support

Xserve RAID - to slow during video capture

I have Xserve RAID with 14 drives in 2 stripes ( 2x7 drives ) in RAID5. I can see in my system two "drives" called RAID1 & RAID2 - each 2.18TB.
When I`m using BlackMagic Disk Speed test utility I have only 150MB/s read and 100MB/s write which is to slow for 1080i HD.
What is wrong ? What should I do to get better performance ?
I`m new in Xserve so maybe somebody could explaine me "step by step" what to do.
I read a little about RAID50 but I have no idea how to create it.
Regards.
Rafal Szermanowicz
www.grupa13.com

Those speeds are fast enough for HD capture.
Anyway, to ensure you're getting full speed, make sure:
1) You have the 1.5 firmware on the RAID
2) Enable controller write cache is checked (enabled)
3) Use drive cache is checked (enabled)
4) Allow host cache flushing is DISABLED (unchecked)
5) Use steady streaming mode is DISABLED (unchecke)
For capture, leaving the settings at 8 stripes as prefetch is probably best. If you are going to be doing extensive playback of uncompressed HD, you may want to consider setting the prefetch at 128 stripes.

XServe-RAID Offsite Backup

I was hoping to use the left controller of the RAID to backup all my clients using TimeMachine and then have the right controller mirror that on the fly (so that would be RAID 50). I was then hoping that I could swap out ALL the right controller drives to store them off-site each week.
Would that plan be possible do you think? OK to take out all drives from the right controller at the same time, leaving the left RAID5 running on its own until the new set is put into the right controller to rebuild the RAID50 again? Make sense? Possible?
Thank you, Grant

However there just doesn’t appear to be any failsafe easy solution to backup the XServe RAID for offsite storage is there. Is is quite unfortunate and surprising and I would have thought there would have been a methodology worked out for this somewhere. But from what I am hearing, there isn’t.
Xserve RAID is a storage array box, and (somewhat confusingly) it's exceedingly uncommon to back up "just a storage box." I do know a few storage controllers that offer replication capabilities, but I'm extremely suspect that the tools work reliably. Storage controllers don't have all of the context on the processing that they need to perform reliable data replication; to ensure consistency.
It's common to perform remote replication via network and tools are available to do that. You almost certainly will end up with local customizations here, too.
The tools are specific to particular application storage involved; there's no Server Time Machine here, as you need use (for instance) mysqldump or you need MySQL replication for a MySQL database, and a different tool for another database. Or you need quiesce the databases.
Which leads various folks to punt on the process, to shut down down the server, and block-clone the disks involved. To quiesce the server. That too can likely be automated, with some scripting and a controlling host.
As for the remote storage (when not using a network), getting the data off-site then depends on what removable media is available. Ultrium tape has decent capacity and good physical reliability and speed, but tends to have poor support on Mac OS X Server, and Ultrium drives and loaders tend to be expensive. Removable disks do reasonably well here, and various options are available, but they're less physically reliable than tapes. For tens of gigabytes, flash media is a potential option, though it's not the speediest of storage.
Networking can be an option here for remote storage, depending on how small your delta (churn) and how good your compression is and how big your network pipe might be; your network pipe has to be big enough to manage your maximum available window.
If you're looking for turn-key, there are commercial products which claim to deal with this stuff. And unless they're using mysqldump or such for databases, I'm professionally skeptical at the integrity of the archives they create on an active server. (I've watched the storage and data archive folks claim to have solved this for thirty years now. They can mostly solve it, too, for some values of mostly.)
[Here is a MySQL mysqldump|http://labs.hoffmanlabs.com/node/1336] procedure, which can serve to show how to do daily, weekly or monthly archives, and how to run mysqldump tool from bash.
(I am aware of one operating system that can mirror active disk data across a data link and across hosts and across storage controllers and can operate with fully distributed shared write, and that OS obviously and specifically targets high-uptime environments, but that OS environment is not cheap. And it's not Mac OS X Server. And even that environment can't correctly capture an active database for an offline archive; even there, you need to quiesce the database or use database-specific tools.)
It'd be feasible for somebody to create a (big, hairy) tool to catch all the usual suspects on a Mac OS X Server box. But then you have to maintain it across all of the slightly-weird installations, and you also have to deal with restorations. (I'd love to write a generic one of these; this would necessarily be a superset of Time Machine. This is a big and complex project, and one that would require extensive testing.)
Server boxes are not client boxes. Servers require real work and real thought and real configuration. And as production requirements increase, they also tend to require some knowledge of the shell and of scripting and writing (or acquiring) some site-management tools.

Windows Server to Xserve Raid

I'd like to use the other side of our raid where drives 1-7 are for Xserver and drives 8-14 are for Win2003 server (6 part of RAID5 with spare). I've a FC card for the IBM x-series, though it has only one port compared to the Xserve's two.
Does the Xserve need both ports used? I'd like to use the FC cable with the FC card on the Win23k server.
Do I just use the RAID Admin to setup the drives then mount the array on the PC (assuming I have still to format and assign letter)?
Has anyone replaced their 250s with 500s in the modules? My Raid firmware is at 1.5/1.50f. I read in a thread and ask if its true that the modules have firmware matched to the drive size? Seems odd. (I would imagine using 750s would mean more heat and issues...)
Thanks for any help!

The two sides of the Xserve RAID are independent. You can plug one fibre cable into the Xserve, and the other into the Win2K3 server, and that's that.
As for "Does the Xserve need both ports used?" that depends on what you mean -- for data you have to have a connection to see the disks. For management, no, you don't need to use both ethernet ports, as they are redundant.
If you replace the drives in the modules, you may lose some functionality, performance, and reliability. This has been discussed here in the forum; feel free to search. As to matching firmware to drive size... not really, you just need a firmware version new enough to recognize 500 GB drives. The 1.5 firmware will recognize Apple's 500 GB modules; don't know about 3rd party drives.

Mac Pro + XServer RAID + FCP2 + Configuration

Hello all. This is my first post here.
I will soon buy a MacPro por video editing on Final Cut Pro 2 and I was wondering if you could help sort out if the configuration I've chosen is the best.
I'll show you the configurations I thought first:
*Mac Pro*
- Two 3.0GHz Quad-Core Intel Xeon
- 4GB (4 x 1GB)
- Mac Pro RAID Card
- 2 x 500gb HDD
- ATI Radeon X1900 XT
- 20" Apple Cinema Display + 23" Apple Cinema HD Display
- Dual-channel 4Gb Fibre Channel PCIe
*XServer RAID*
- 2000GB ADM (4x500GB Ultra ATA)
- Cache Battery Back-up Modules
- Dual-channel 4Gb Fibre Channel PCIe
My idea:
A) The MAC Pro I'll be used for 3D rendering and video editing. I'll configure the 2x500GB with RAID1 (mirroring) for a fail safe env, leaving my with 500GB of available space
B) XServer RAID will be connected directly to the Mac Pro (for now) via the fiber optic cards and we'll provided additional storage.
C) For projects stored on the XServer RAID (videos for example) I must be able to access and edit directly with FCP2 without having to pass it to the Mac Pro
D) I was thinking of using RAID5 for XServer RAID configuration leaving me with 2.64 x 500GB (as described on support faqs) = 1.3 TB of disk space with a reasonable fail safe environment (RAID5 with 3 drives allows one drive to fail and offers a good recovery rate).
OK. My questions:
1) Is my MacPro config enough for FCP2 + 3D Rendering ?
2) Can I use the XServer RAID directly with Mac Pro or do I need aditional software / hardware?
3) Can I connect the fiber optic from one board to the other without using the router? (on google the answers I found were very vague...)
4) Is the RAID5 the best choice (in terms of performance vs data recovery) for video editing. The RAID5 specs states that random writes to disk are slower that other RAID configs. Is RAID 50 (5+0) a better choice?
5) I opted for the 4 HDD config on XServer but I could change to a 7 HDD config for a similar total space.
I'm sorry for the long post, but I can't find anywhere suitable information about this questions.
Hope to hear from you.
Thanks in advance!

We have a ton of Xserve's and Xserve RAID's at my work. As of right now they're all directly connected to our servers with Fibre Channel cables (NOT fiber optic, totally different animal.) We finally just bought our first Fibre Channel switch to hookup five 10.5TB RAIDS and a huge tape loader for backups. The RAID's work perfectly when directly connected and are very fast. The only reason that you would need a Fibre Channel switch is if you want multiple machines to be able to access the array without using network shares.
I really don't think that just four drives will give you the performance that you're looking for. In order to get good performance out of a RAID5 you NEED as many spindles as you can get. If you're stuck to a budget if would probably go to smaller drives but get more of them. I think you've already discovered this but if you want to do a RAID5+0, you'll need to populate drives on both sides of the RAID as they are physically seperated.
As far as I know, you can only get Xserve RAID Drive Modules from Apple as they do some pretty intensive testing on every drive before they ship. You can't even buy empty modules, you can buy blanks but they don't include the required electronics.

Switching to Xserver/Xserve RAID

Hi boys and girls...
I was looking for a little assistance in switching over to Xserve. Let me give you some background info first.
Were a small studio in London, with only 11 people in-house and the majority working externally whether free-lance, from home or from another country etc. Were mostly Mac based, though 4 machines are those little beige pc things all running XP 2002. At the minute its 1 G5 and a collection of G4 tower's and G4 power book's, G4 cube's and so on. Were all connected to a G4 server running Mac OS X Server 10.2.8 with a very small dual 120GB HD raid thing running Retrospect.
Our problem is, this system was set up some time ago and were starting to outgrow it.
What were looking for is a way to backup all of our current work and archive all of our old work. Most users like to work directly off the server as theres so much file sharing between the macs and pc's, directly updating files so there isnt any duplication etc.
First question, is it possible (and a good/bad idea ?) to have 10-15 users working directly from a Mac server, that stores the archived work for users to reference and also current work which is backed up to tape and duplicated (as we currently have) to another HD?
Secondly, Is the ideal way to be running things? Is there a more efficent way?
Finally, what kind of spec should we be looking at? There's such a huge difference between servers, while were willing to invest, we dont want to go crazy (maybe a little) on costs.
I look forward to your responses and thank you in advance
Marcus

There are certainly some drawbacks with your current setup that mean you should make some changes.
In general, there's nothing wrong with working with files directly off the server, however, 10.2.8 has some issues with multiple users accessing the same files at the same time, so you should look to move to 10.4 ASAP to address that issue, regardless of any other changes you make.
I am assuming that the remote users don't work this way - uploading/download files as appropriate - it would be painful to work off the server remotely.
The only real disadvantage with working with files directly off the server is that if a file is changed erroneously and saved, there's no easy backup.
If the file was copied to the local drive and saved, it's easy to roll back to the previous version by re-copying it from the server, but if that change is saved directly to the server the only rollback involves pulling out Retrospect.
The other change that would make a difference is installing a gigabit switch and connecting the server to it. Even if all the host systems don't have gigabit ethernet, the extra bandwidth to the server will definitely help.
As for a new server, 10-15 file sharing users are not likely to stress the server, do you don't need a top-of-the-line configuration.
You should first decide how much disk space you need. With 500GB drives, the XServe can handle up to 1.5TB on its own, without any additional XServe RAID. However, you might want to consider RAID (using RAID you're limited to 1TB of RAID 5 storage, or 500GB of mirrored storage in the box).
In addition to your current data usage, consider using an online disk backup where multiple copies of the data is stored on the server itself before (or in addition to) backing up to tape.
While tapes offer several long-term archive advantages, they really don't work so well for quick restores of a file or two. Having a snapshot of the last couple of days data online makes it trivial to step back a day or so without having to resort to tapes. This may mean, though, that your 100GB of data requires 200 or 300GB of disk space.
If you do decide than an XServe RAID is the right solution, consider getting it right-sized from the get-go rather than buying it small (e.g. 4 drives) and adding later. While it can be done, adding drives to an existing array is a PITA.
If you do opt for an XServe RAID, and you don't currently have any rack-mounted equipment, consider using a PowerMac G5 as your server rather than an XServe. While similar in terms of performance, the PowerMac can work out cheaper depending on configuration.

Clarification on how to use Xserve Raid and Fibre Channel without xsan.

First let me apologize for not responding earlier to your response, I tend to get busy and then forget to check back here.
Tod, the answer to your question is No, only one computer is accessing the xserve raid files at any one time and that is via Fibre Channel. However I do have the xserve raids set up as share points via ethernet.
Maybe I should turn that off and only access the files with the one computer that can connect via fibre channel.
I never thought of that. I will try that while I await for your answer, thanks again.
Todd Buhmiller
I have the following setup:
Xserve: 2x2Ghz Dual Core Intel Xeon, 5Gb of Ram, Running 10.5.8 Leopard Server
Xserve Raid with firmware version 1.5.1/1.51c on both controllers, and
Qlogic Sanbox 5600
Apple Fibre Channel Cards in Xserve, and Mac Pro Tower; Apple 2 Port 4Gbs Fibre Channel Card
Mac Pro Tower-Quad Core Intel Xeon 2.8Ghz, 16Gb of Ram, Running Snow Leopard 10.6.4
Here is the problem.
The directory for the xserve raids keep getting corrup, and I use disc warrior to rebuild them. Is there a way to keep the directories from getting corrupt? I am a few pieces of equipment before I can build an Xsan as that is the ultimate goal, but until then, I just need to be able to have the raids funciton as storage without having to rebuild the directories all of the time.
Anybody have any suggestions?
Thanks
Todd Buhmiller
Widescreen Media
Calgary, Alberta Canada
Tod Kuykendall
Posts: 1,237
From: San Diego
Registered: Oct 11, 2000
Re: Xserve Raid Mounts, Corrupt Directory tired of rebuilding directory
Posted: Jun 27, 2010 1:25 PM in response to: Todd Buhmiller
Are multiple computers accessing the same data on the RAID at the same time?
If so then NO. This is the source of your data corruption and I'm surprised if you were able to get all your data back every time if this is how you've been running your system. Each fibre channel assumes it has full and sole control of every volume it has mounted, no data arbitration is practiced and data corruption will occur if this assumption is wrong.
The only way this set-up will work is to use partitions or LUN masks so the volumes are accessed by one computer at any time. As long as one computer relinquishes control before another mounts it you will dodge arbitration issues but this is a dangerous game. If you screw up and mount an already mounted volume - and there is no easy way to tell if a volume is mounted - corruption will then occur. Sharing data simultaneous at fibre speeds is what XSAN does and to do this you need it.
HTH,
=Tod
Intel Xserve, G5 XServes, XRAID, Promise

+The xserve raids will mount automatically to any computer that I connect the qlogic fc switch to+
This is source of the corruption to your data. Any computer that attaches to a drive/partition via fibre channel assumes that it alone is in control of the drive and data corruption is inevitable.
+Is that the issue, should I disconnect the xserve from the fc switch and leave it connected via ethernet?+
Short answer: YES. The ethernet connections are fine because the server is controlling the file arbitration through the sharing protocol. Fibre channel connections assumes complete control over the partition and no arbitration of the file access is performed. It's like two people independently driving trying to drive the same car to different locations.
Depending on your set-up it is possible for the two machines to see and use different parts of the Xserve RAID storage but they cannot access the same areas without SAN doing the arbitration.
Hope that's clear,
=Tod

Xserve RAID lost RAID 5 array on right/bottom controller

I cleanly shut down an Xserve G5 with an Xserve RAID attached and then powered off the Xserve RAID this morning. I replaced a failing memory module in the Xserve and moved the rack 6". I then powered on the Xserve RAID, waited for a couple minutes until it was fully booted, and then booted the Xserve. When it came up, my RAID 50 volume failed to mount. Upon further investigation, it appears that the RAID 5 array on the right hand disks is "gone". In RAID Admin (Disks and Drives tab), the left side array is visible, but all disks on the right side list status as "OK" and Type: as "Spare".
Configuration: Xserve RAID with 14 250 GB disks. Each side was configured with 6 disks in a RAID 5 array and one spare. These were striped using Software RAID on the Xserve into RAID 50 and mounted as a single volume. The RAID firmware is currently 1.5 and the Xserve is running OS X Server 10.4.3.
To summarize today's activities: under Apple's guidance (as this entire system is covered under a Premium Support contract), I swapped the (bottom) controller for the right side, updated firmware (from v1.3/1.20a to 1.5/1.50), multiple resets of both controllers, repeated forced firmware updates, etc.
Also, I swapped the left set of disks for the right set, and the array from the left set now shows up on the right side, and the missing array from the right is still missing with the disks on the left side. I replaced the disks to their original positions with the same results.
RAID Admin's Utility "Recognize Array" will not perform any operations on the rigth side disks and Apple tells me that there's nothing further that I can do with it.
None of this has solved the problem or substantially changed the issue, and the disks on the right side are still missing their associated array. Apple is unable/unwilling to offer any further help except to refer me to 3rd party data recovery services.
Does anyone have any suggestion at all that might possibly recover the missing array? Is anyone aware of any tools that I might use to recreate the RAID 5 array on the right controller? I was hoping that there might exist some low-level tools with which the disks could be recreated into an array by hand? Are there any commercial products that would work on this? Any other ideas?
Many thanks for any suggestions.
- Martin
Xserve RAID (14 250GB disks) on Xserve G5 Mac OS X (10.4.3)

Not sure why you swapped the controllers back and forth
William, I don't think I was clear on this. I swapped the controller with a new controller that I had in a spare parts kit. This was at Apple's request.
really, RAID is not a backup...
I'm well aware, but despite my incessant warnings, users will become lulled in to a false sense of security when something "just works" for a very long time. This array wasn't intended to store valuable data that couldn't be lost, but...
It may be possible for Apple to re-create the RAID set, did you ask AppleCare about the possibility?
Apple has told me more than once that there's nothing else that they can do for me...and yet I keep calling back.
I was surprised that this array was lost when there were absolutely no prior signs of a problem and the system was merely shutdown and restarted cleanly. I'm more surprised and quite disappointed to learn that Apple will do nothing else for me (under a Premium Support contract) to attempt to repair a damaged array. When I asked questions about where the RAID information is stored, I received the answers: "I can't tell you that" and "Apple doesn't release that information". I did not get the feeling that they were working with me, but rather holding my hand while they walked me through published documentation.
I expected that there would be utilities (analagous to filesystem repair utilities) such as RAID Admin's "Recognize Array" that could help repair and recover damaged array data. I think that the lesson that I've leanred today is that I was naive to have expected such a thing without actually having investigated it ahead of time.
Anyway, thanks for your input, William.

Configure Xserve RAID as a single RAID 5 array?

We just picked up a used Xserve RAID with 14x750GB drives, and we want to configure the entire unit as a single RAID5 array. RAID Utility will let us configure each side as a separate array, but not both sides in a single array. Is this not possible or are we just missing something simple?

No, each side of the RAID is logically separate so while you can create a RAID 5 on either side there is no way to create a single RAID5 of the unit. You can create a RAID 50 and make the 2 RAID5s into a single volume software RAID 0 by using Disk Utility to join the two 5s into a single volume but that's as close as it comes.
HTH,
=Tod

Problems with Xserve RAID

I have been having problems with Xserve RAID, which happened in a close time span, but may not be related. The Xserve RAID is set up with 7 disks with RAID 5, totaling to 1.3TB in storage capacity.
First, the first disk failed and the RAID system was degraded. Since I got a very similar 250GB harddisk (but without "Apple Firmware") I tried putting it as a replacement. It was recognized but it became a hot spare disk, even though I did not set the system to use hot spare.
Later Mac OS X reported that the Xserve RAID's 1.3TB volume was unmounted. I check with Disk Utility, and it reported a lot of errors. I ended up with about 70GB of files in lost+found, and I confirmed that many files were missing. Disk Utility could not really fixed it.
I put back the failed disk, and Xserve RAID successfully rebuilt the array. I did "Background Array Conditioning" to perform surface scan and mapping of bad blocks. It completed without error. I then did "Verify Parity Data", and it completed but with error, as follows:
Event:
Disk 5 Reported An Error. COMMAND:0x37 ERROR:0x64 STATUS:0x81 LBA:0x119E6880
Description:
The drive reported ATA error. This is a failure in the communication from the RAID Controller to the drive.
Any idea what is happening with this Xserve RAID? Bad disk? Bad controller? Or what? Any help is appreciated.
Thanks,
Xserve RAID Dual G5 2.0GHz Mac OS X (10.3.9)

After reading here and there on the net (including this forum), yes I realized that the "Apple Firmware" thing may be significant after all. But since I set the Xserve RAID to use RAID 5, a failure of one disk should not affect data integrity. And surface scan was successful, implyingthat all disks are now free from defects. So why did it lost 70GB worth of data? I experienced disk hardware failure often with Windows system but never experienced losing data while the hardware seems to be fine. Without knowing why this happened, I feel scared to put data on Xserve RAID, and this is ironic since this 1.7TB Xserve RAID is meant for storing data safely...

How can I fix slow AFP writes to our Xserve RAID?

Hi,
This problem has been posted before but I couldn't find a solution. We have a Intel Xserve connected via fibre channel to a 14 disk 10.5 TB Xserve RAID. It's setup as two RAID5 volumes soft raided into one volumes (RAID 50).
There are multiple AFP shares on the RAID being served by the Xserve. The problem is that writes over AFP randomly go really slowly. Sampling using fs_usage shows a load of RdMeta operations from the AppleFilerServer process. I think it's the same issue that was posted here:
http://discussions.apple.com/message.jspa?messageID=8153758#8153758
We've tried everything mentioned in that post - with no success. Has anyone managed to solve this problem? Many thanks,
Jamie

It might be an HFS+ filesystem but because I'm seeing this on a simple striped RAID in a PowerMac. I was writing a script to look for system files starting with 32 zero bytes:
find /System/Library/ -type f -exec echo -n "{}:" \; -exec xxd -l 32 -c 64 -p {} \; | grep ':0000000000000000000000000000000000000000000000000000000000000000' | cut -f 1 -d':'
Sometimes it appeared to halt for a long time and fs_usage showed RdMeta or WrMeta blasting along at ~100MB/s. After a few more runs it no longer has this problem. I wonder if there's a tuning bug in HFS hot file management or defragmentation.

XServe RAID RAID5 performance?

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