Adding Drives to an Existing RAID 0 Stripe Set

I have 4 HDDs (250x1 and 320x3). While the OS is installed on the 250gb disk the rest of the three disks are striped.
I want to share files that are on my RAID Set. As OSX supports sharing of files only in the HOME directory, I now want to reinstall OSX on my stripe set.
My questions!?
1. Can OSX be installed on a striped set?
2. Can a fresh (identical) HDD be added to an existing RAID 0 set (configured using the Disk Utility)?
3. Is it possible to install OSX 10.4.x Tiger on a MAC Pro with 4 HDDs all configured as RAID 0 OR as RAID 1 (2HDDs) / RAID 0 (2 HDDs) Combination?
4. Can the default Home Directory location be changed to another volume, other than the startup volume?
Thanks in advance!

1) Yes.
2) Yes although the data on the current RAID set will be deleted.
3) Yes.
4) Yes.

Similar Messages

Disk utility & adding to existing RAID 0 set

Hi all,
I have a RAID 0 set-up with two 1TB drives, it works just great for what I need, but I am running out of space. And I thought 2TB would be more than enough!!!!!
Just a thought, but can I add another 1TB disk into the RAID (same manufacture & model) and increase the size of the raid set without wiping the contents of the existing RAID 0 set?
Not sure is OS X software RAID would add this as data or a parity disk? Destroy my data and rebuild a new RAID 0 with three disks as data or what?
Any help appreciated.

Hi Tim Cox;
No you can't add another disk to a RAID 0 array.
The way raid 0 works is that it breaks up the data into block that are then written in turn to each of the drives in the array. You can think of this a little like dealing cards when playing a poker. So your data is now spread across two drives. There is no way to spread it across another one so you are not able to add the additional drive.
In order to add the new drive all of the drives would have to be reformatted which will erase all data. So anything currently on the two drive RAID 0 array would have to be backed up first.
What are you currently using for backup?
If either of the two drives were to fall right now you would lose everything. So when using RAID 0 backup is extremely important to protect your data from loose.
Allan

Cloning a single drive to a new RAID 1 set

Hi,
Can I clone a drive from a machine (that has dual controller, RAID 1 capability but, was not setup using it) to a new pair of hardware RAID 1 disks using method/software in the same machiine, now. I think the machine should have originally used it's hardware
RAID 1 capability but, for whatever reason wasn't and now, I would like to do that. Can I use Acronis or Ghost to clone the single drive to the new RAID 1 set?
Thanks.
gk

It is possible to create a mirror from an existing JBOD disk, however the ability to do this depends on the capabilities of the RAID controller. In my experience, this is something found on high-end controllers, of which I know exist but have not used.
There is a method using some 3ware cards where you have to take a disk image of the single disk. Then you import it into a mirror but the drive is erased. Then you can redeploy the disk image onto the mirror.
Of course there is a big problem you may encounter. You would only want to do this if the disk was originally on RAID JBOD. If the disk was originally on IDE or AHCI modes, going through this process would likely result in Windows STOP 0x7B on first boot
after being cloned to the mirror.
If the data is important on this disk, I would recommend not trying to put it into a mirror. Instead you can use Ghost (or similar) program to do a sector copy to a new disk. I typically recommend that the new disk be a different size from the old disk so
you can easily determine which is which.

Optimizing RAID: stripe/chunk size

I'm trying to figure out how to optimize the RAID chunk/stripe size for our Oracle 8i server. For example, let's say that we have:
- 4 drives in the RAID stripe set
- 16 KB Oracle block size
- MULTIBLOCK_READ_COUNT=16
Now the big question is what the optimal setting is for the chunk/stripe size. As far as I can see, we would have two alternatives:
- case 1: stripe size = 256 KB
- case 2: stripe size = 64 KB
In case 1, all i/o would be spread out over all 4 drives. In case 2, we'd be able to isolate a lot of i/o to separate drives, so that each drive serves different i/o calls. My guess is that case 1 would work better where there's a lot of random disk i/o.
Does anyone have any thoughts or experience to share on this topic?
Thanks,
Alex Algard
WhitePages.com
null

It does not matter. Do not mix soft-raid and hard-raid. One OS i/o operation can read from one disk and number of disk. Do not forget about track-to-track seek time.
Practice is the measure of truth :)
For example, http://www.fcenter.ru/fc-articles/Technical/20000918/hi-end.gif

RAID Stripe, slice failure.

I have a RAID stripe set up on 3 disks, and I had a slice failure. Anybody know how I can remove the slice and recover the data on the other 2 disks?
Since OSX and all Unix-y OS's like to keep files contiguous, the loss should be minimal if i can only recover the data from the two remaining good drives - any suggestions?

I do have a backup, problem is, all the data I really need to recover is newer than my backup. 8-( Logically it ought to be recoverable -- because *nix file systems like to keep files contiguous, it stands to reason that the files themselves are contiguous on the two remaining good slices.
I understand and do not doubt that you speak from experience -- it's just that I understand a Windows file system being unable to recover said data - files being fragmented from one end to the other. But an *nix file system??? There is really no good reason why not.
None that I can think of anyway. It's not like Darwin fragments a file all over the place. 8-(

RAID 5 Set Suddenly NOT VIABLE!

I'm running an early 2008 Mac Pro with an Apple Raid Card with 4 internal, 1TB drives formatted into a single Raid 5 set. The raid card has had numerous issues in recent years, mainly drives that would unexpectedly drop out of the Raid and list as "roaming". In those past cases, Apple had me shut down the computer, remove the drive sled of the problem drive, wait a few minutes and replace the drive then restart. On one occasion, the Raid set was back to normal, on other occasions the drive was seen and I would have to assign it as a spare and rebuild the set. Everything would work fine until the next time.
In the last few days, I discovered the Mac Pro shut down, after I had left it idle for a while with the screen asleep. When I tried to restart, I was greeted with a blank grey screen, no Apple, no anything. I tried booting from CDs and external Boot Drives with no luck. This morning I was finally able to boot onto an external drive and discovered my Raid 5 set is now "NOT VIABLE!"
ALL drives are listed "Verified" and "Good." Bays 1 and 2 are "assigned" while Bays 3 and 4 are listed as "Roaming." The Volume is showing "Degraded" and the Raid Set is listed as "Not Viable." I have tried shutting down and removing all the drives then reinserting them (in their original slots) and restarting, but nothing changes.
Is there any way I can get these two drives to assign back to the Raid Set WITHOUT losing all my data? Is there any way to recover all may data? Am I hosed here and everything is a loss?
Any help will be greatly appreciated.
Thanks in advance.
Brett B.
Here is a screen capture of what Raid Utility reported:

In my experience, Apple RAID in general (with RAID card or without) does not tolerate a very high error-retry rate from the Drives.
I had a mirrored RAID that repeatedly became Degraded, and decided to take strong action. I made sure I had two Backups, then pulled out the Drives and erased them with Write Zeroes, one pass. One of the drives had more than 10 blocks that needed to be "spared", so Initialization Failed. I ran the procedure multiple times and found that 30 blocks had needed to be spared. If any of these had been marginal in daily use, it could have caused the drive to get (what appears to be) stuck doing dozens to hundreds of retrys, but still not throw an I/O Error that would bring the system to a Halt.
Google did a very large study and concluded that there is a very high probability that drives with multiple errors will end up being replaced within about six months. They attributed this to a cascade of additional errors that often followed the first group detected, leading to the drive being declared unusable.
In my opinion, just reseating the drive (combined with rebuilding, which does re-write the data blocks) may not be strong enough medicine to fix a recurring problem. A drive may repeatedly be doing multiple retrys on some data blocks, or may have Bad Blocks.
I suggest you Zero the troublesome drives (which takes many hours each). If Disk Utility finds more than 10 blocks that need to be spared, or if the drive runs out of available spares, it will report "Initialization Failed!" Consider such a drive not good enough for use in a RAID and replace it with a new one. Or just rebuild your RAID with different (e.g., larger) new drives.

Adding Drive to Concatenated RAID in Disk Utility

Hello,
I'm having a spot of trouble with Disk Utility. 24 hours ago I added a new drive to a Concatenated Raid through Disk Utility, and clicked Update to set the process going.
Now it's not responding. It just claims to be updating. I struggle to believe that it takes this long though!
I didn't format the disk before adding it to the RAID. Is this what's causing the upset?
When I try to cancel it tells me I risk losing data on the disk. I'm not sure if it means the new disk or all disks on the array - which is a terrifying prospect. If I quit Disk Utility, will my existing data on the array be safe?
Thanks in advance for the help,
Ben

The drives are in Sonnet P500 enclosures and connected to the MacPro via a Sonnet SATA card.
On purhcase I was told this could be done, as it's a Concatenated JBOD setup. For a better description of what I mean by that, this wiki article describes it well http://en.wikipedia.org/wiki/StandardRAIDlevels.
Does this provide any further clues?
Currently there are 7x 1TB drives in 2 enclosures. I've now added 2 more 1TB drives. I can currently see and continue to use the data on the existing 7 drives. My worry though is that if I quit the disk utility I may lose the data on the 7 original drives.

How can I boot to a fakeRAID -Raid0 set drive from a non-raid hdd

Hi all,
First of all, my English is bad and I hope I can explain it what my problem is. Secondly, I need your expert help with my problem right now.
I'll just layout some hardware information and some history before I start. Currently, my motherboard has 3 hdd controllers which are:
1) Intel - 6 ports --> contains 2 sets of RAID drives = 2 x 60gb SSD (boot drive) and 2 x 500gb HDD (data drive) both in RAID 0
2) Jmicron - 2 ports --> 1 port is used by the DVDROM
3) Marvell - 2 ports --> I don't use these ports as they are slow and are so bad - currently disabled in BIOS
HISTORY: Before, my 2 x 60gb SSDs (RAID 0) contained Arch 64 + Windows 7 64 with Grub as the main bootloader. I remembered having a hard time setting up intel fakeraid with Arch linux + Win7 dual boot before, but fortunately, with your help, I found the solution and I've been using it ever since until today.
NOW is kind of a different issue. I bought a new 60gb SSD (just one). I totally reformatted everything with my 2 x 60gb SSD Raid 0 and I decided to just use that exclusively for windows, still in RAID 0. My brand new SSD will ONLY have Arch64 on it. So I installed Windows 7 first on my Raid SSD set. I plugged my new SSD to the Jmicron port so I can take advantage of AHCI. I don't want to mix my new SSD to the Intel Controllers since its not RAID anyway. Anyway, I installed Arch 64 on the new SSD in the JMicron Port fine.
Now here comes the problem, I set the Jmicron port where the Arch is installed to be the primary boot in the BIOS (since GRUB is there) and I can't boot to Windows! It gives me an error that It can't find the target drive (Win7 in the Raid 0 - intel ports). I've tried modifying the menu.lst and trying so many combinations and It still fails. Of course, I can boot to Arch fine since the drive is independent. It looks like grub legacy can't boot to fakeRaid drives if its not installed on that same drive.
Can you give me advice on how to fix this issue?
Also, I was just thinking, is there a 3rd party Windows Bootloader, that can be installed in Raid 0, that can pick up Linux and boot from it. I was thinking of just making the Windows 7 as primary boot in BIOS, with a 3rd party bootloader, then just boot to Arch.
Thank you!

Yes, I have redirected my User folder to the D: drive.
I know that some shared components must reside on the C: drive; that's fine. I just don't have room for the entire installation on there.
The real issue here is that, when a drive other than C: is selected as the destination, the CS6 package installs into a broken state every time, out of the gate, on my system. Some components get installed to D: and some to C:, but the various components of the programs seem confused about what exists where, as shown below:
I select a folder on D: as the destination folder for the install, and here is what I get:
64-bit versions of the package -- Program files are installed to the D: drive as specified, but attempting to start them results in a configuration error message stating that the program must be uninstalled and reinstalled, and lists "Error code: 1".
32-bit versions of the package -- Program files are installed to the C: drive against what I specified. The shortcuts installed in the Start menu for the 32-bit versions point to the locations where these program files SHOULD be, on the D: drive. If the Adobe folder containing the program files is copied over to the correct location on D:, these programs function normally with no errors.
I have the 32-bit versions working by copying the program files from C: to D:. I just want to get the 64-bit versions working as well.
Any help you could give would be greatly appreciated; I'm really looking forward to testing the CS6 suite on my system!

Adding A New Drive To A Software RAID 5 Array

Edit 3: Just mounted the partitions and I can delete them because they contain nothing special. Is it safe to expand the 2nd partition of each drive to fill up the left over 22 GB?
Edit 2: I just deleted all the partitions off of my new drive and created one partition, then added it to the array and it works just fine. My next question is, can I delete all the smaller partitions and expand /dev/sd[x]2 to reclaim all the space (about 70 GB)?
One of my drives failed and Western Digital sent me a new drive, except it was an external drive instead of an internal drive, so I cracked it open and the label looked different. Turns out it's just refurbished and it's the same model as my other drives (WD Caviar Green 3 TB).
I've read through the wiki article on Software RAID and created the partitions exactly the same as my other drives, but while creating the main 2.7 TB partition it says that the ending sector is out of range when it isn't. I'm new to all this so I have no idea what to do. From what I've read there normally aren't this many partitions per disk, correct? I also have md124, md125 and md126 for the other partitions. md127 is for the 2.7 TB partitions. I took the array out of my Thecus N4520. I have a 3 TB external drive and a 1TB internal, along with another 500 GB drive. Would I be better off at destroying the RAID set and creating a fresh RAID 5 set, considering I'm losing about 90 GB if I don't need the smaller partitions.
/dev/sdc
Disk /dev/sdc: 5860533168 sectors, 2.7 TiB
Logical sector size: 512 bytes
Disk identifier (GUID): 00636413-FB4D-408D-BC7F-EBAF880FBE6D
Partition table holds up to 128 entries
First usable sector is 34, last usable sector is 5860533134
Partitions will be aligned on 2048-sector boundaries
Total free space is 43941 sectors (21.5 MiB)
Number Start (sector) End (sector) Size Code Name
1 41945088 46139375 2.0 GiB FD00
2 47187968 5860491263 2.7 TiB FD00 THECUS
3 46139392 47187951 512.0 MiB FD00
4 2048 20973559 10.0 GiB FD00 i686-THECUS
5 20973568 41945071 10.0 GiB FD00
/dev/sdd
Disk /dev/sdd: 5860533168 sectors, 2.7 TiB
Logical sector size: 512 bytes
Disk identifier (GUID): C5900FF4-95A1-44BD-8A36-E1150E4FC458
Partition table holds up to 128 entries
First usable sector is 34, last usable sector is 5860533134
Partitions will be aligned on 2048-sector boundaries
Total free space is 43941 sectors (21.5 MiB)
Number Start (sector) End (sector) Size Code Name
1 41945088 46139375 2.0 GiB FD00
2 47187968 5860491263 2.7 TiB FD00 THECUS
3 46139392 47187951 512.0 MiB FD00
4 2048 20973559 10.0 GiB FD00 i686-THECUS
5 20973568 41945071 10.0 GiB FD00
/dev/sde
Disk /dev/sde: 5860533168 sectors, 2.7 TiB
Logical sector size: 512 bytes
Disk identifier (GUID): 2B5527AC-9D53-4506-B31F-28736A0435BD
Partition table holds up to 128 entries
First usable sector is 34, last usable sector is 5860533134
Partitions will be aligned on 2048-sector boundaries
Total free space is 43941 sectors (21.5 MiB)
Number Start (sector) End (sector) Size Code Name
1 41945088 46139375 2.0 GiB FD00
2 47187968 5860491263 2.7 TiB FD00 THECUS
3 46139392 47187951 512.0 MiB FD00
4 2048 20973559 10.0 GiB FD00 i686-THECUS
5 20973568 41945071 10.0 GiB FD00
new drive: /dev/sdf
Disk /dev/sdf: 5860467633 sectors, 2.7 TiB
Logical sector size: 512 bytes
Disk identifier (GUID): 93F9EF48-998D-4EF9-B5B7-936D4D3C7030
Partition table holds up to 128 entries
First usable sector is 34, last usable sector is 5860467599
Partitions will be aligned on 2048-sector boundaries
Total free space is 5813281700 sectors (2.7 TiB)
Number Start (sector) End (sector) Size Code Name
1 41945088 46139375 2.0 GiB FD00 Linux RAID
2 47187968 47187969 1024 bytes FD00 Linux RAID
3 46139392 47187951 512.0 MiB FD00 Linux RAID
4 2048 20973559 10.0 GiB FD00 Linux RAID
5 20973568 41945071 10.0 GiB FD00 Linux RAID
when I type in 5860491263 as the end sector gdisk does nothing, just wants more input. If I type +2.7T it accepts it, but really it just creates a partition that's 1KB in size!
I am able to create a 2.7 TB partition with an end sector of 5860467599, this won't screw anything up will it?
Edit 1: just tried it and got this
[root@ra /home/bran]# mdadm --add /dev/md127 /dev/sdf2
mdadm: /dev/sdf2 not large enough to join array
[root@ra /home/bran]# fdisk -l /dev/sdf
Disk /dev/sdf: 2.7 TiB, 3000559428096 bytes, 5860467633 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: gpt
Disk identifier: 93F9EF48-998D-4EF9-B5B7-936D4D3C7030
Device Start End Size Type
/dev/sdf1 41945088 46139375 2G Linux RAID
/dev/sdf2 47187968 5860467599 2.7T Linux RAID
/dev/sdf3 46139392 47187951 512M Linux RAID
/dev/sdf4 2048 20973559 10G Linux RAID
/dev/sdf5 20973568 41945071 10G Linux RAID
Last edited by brando56894 (2014-04-28 00:47:29)

Sorry I numbered them to show the flow of information, this was also just a place for me to store info as I worked through it. I managed to get it to work by creating a partition that takes up the whole drive and is actually 22 GB larger than all the other drives (since I found out that the had root, swap and home partitions that are no longer needed).
I should be able to resize the other partitions without a problem, correct? They're EXT4. Should I unmount the raid array and do them individually, remount the array, let it sync and do the next? Or just unmount the array, resize all of them, mount it and let it sync?

Adding Drives to a RAID 5

I have a XSERVE RAID with 4 250GB drives configured as a RAID 5. We're starting to get low on space so I'd like to expand the capacity by adding some drives.
Is there a specific number of drives I need to add or can I add 1, 2 or 3 drives as long as they're on the same controller?
Mac OS X (10.4.6)

This is incorrect.
The Xserve RAID does not ship with any file system on it whatsoever. It is just disks, set up in a RAID configuration that you specify.
You can format the RAID volume as HFS+ if you connect it to a Mac. You can format it with NTFS if you connect it to a Windows machine. Or ZFS on a Solaris box, etc.
What you CANNOT easily do is grow a volume. Period.
Buy the RAID with 7 drives, or with 14 drives. If you buy a "2 TB" one (what is this -- 4x500 GB drives? Recall that is about 1.3 TB of usable space in RAID 5)... plan on reformatting if you add 3 drives later. Plan on it. I mean it: plan on it. Growing the RAID is complicated and unless you want to set up a concatenated RAID set, it's what you MUST do to grow the volume.
Again, my advice could not be clearer (search back as well, I've stated this many, many times): Buy the RAID with 7 drives, or with 14, and NEVER plan on growing the RAID by adding drives WITHOUT reformatting. Period.

Upgrading my existing RAID to higher capacity drives

Hi all,
I currently have two 500GB drives as a RAID 1 (through Disk Utility) in my mid-2007 Mac Pro 8-core, and I'm starting to get a little tight on space. I'd like to up the capacity by replacing the existing 500GB drives with at least 1TB drives, but with all four drive bays currently filled, I'm not sure how to go about this... but after reading through some threads here, I might have plan.
Would this be the best course of action?
1) Remove one of the 500GB RAID drives.
2) Delete the RAID set in Disk Utility.
3) Install new 1TB+ drive
4) Clone the remaining 500GB RAID drive to the new 1TB+ one.
5) Remove remaining 500GB RAID drive, install new matching 1TB+ drive
6) Create new RAID set in Disk Utility
It seems a little roundabout, but sounds like it would work. Any thoughts, or better ways of going about doing this?
Thanks,
Jeff

There are three obscure sources for the documentation. Bear with me. I have tried to focus narrowly on helpful documents that I actually used to do this, not baffle you with B.S.:
1) Man pages for the Terminal diskutil command:
try this link or use the procedure below:
Mac OS X Reference Library: diskutil(8) Manual page
.OR.
Start Terminal.
type man diskutil
The problem with this document alone is there is no background information, no discussion of what you are actually doing, and no examples.
You will want to look at the options for the diskutil createRAID.
Once this drive is created and populated with your data, you can use diskutil to rebuild onto the second drive, but frankly it is easier and more confidence-inspiring to use Disk Utility.
2) Server Admin Command-Line Administration Manuals:
Introduction to Command-Line Administration : Version 10.6 Snow Leopard
This is a broad introduction to using the command-line. Many parts apply perfectly well to Mac OS X non-server. It lacks the specific diskutil chapter featured in the previous version:
Command-Line Administration :For Version 10.5 Leopard
see chapter 7, "Working with Disks and Volumes" for specific examples. I printed chapter 7 out to use as a reference. As far as I know, this applies perfectly well in 10.6. This is also a little terse, and short on examples.
3) afp548 (a Mac OS X Server discussion/help site) articles discussing RAID2 ( introduced at 10.4 Tiger):
afp548: Apple RAID2 In Depth
and a slightly older article on Rebuilding a RAID Mirror with diskutil command-line:
afp548: How to Build a RAID Mirror Without a Re-Format
The examples in the second article show only the older Apple Partition Table (rather than GUID) partition maps, but the fundamental info is still good.
Message was edited by: Grant Bennet-Alder

Is it possible Adding another 2 harddrive sas 2.5' hot plug on existing raid 1 ????

Dear All,
I have HP ML370 G6 with 2 harddrives sas 2.5' 300GB hotplug on raid 1.
And it is almost runout space. I have plan to adding another 2 harddrive with same type.
Is is possible to add another harddrive on raid 1 without change or re-install the operating system installed ??
My operating system is Redhat Enterprise Linux 4 (RHEL 4) and oracle database inside.
Please I need your suggest and advise, what should I do to add more space on existing raid 1.
Thank You,
breakthelimit

There is no BIOS in OS X. There is only the EFI stored in ROM that is not user modifiable. OS X is probably checking Bay 0 for the boot drive since that is where it should be. It won't check the Tempo drive since it is treated like an external drive. I suggest you open Startup Disk preferences to see if the Tempo device is selected as the boot device. If it isn't, then select it. That will probably shave off a few seconds in the startup time.

Adding more drives to my x-Raid

hello,
I'm running out of space on my x-raid, and need to upgrade it asap. right now, there are only 4 x 180GB drives in it. my question is do I have to use the same capacity drives to expand my raid? I'd rather go with a larger hard drives if possible of course, but need to make sure it will be able to handle it.

Ok, as I've been reading more and more, I'm realizing that I know nothing about RAIDs on Apple I've done some on PCs but it was easier Oh MACs
anyway, here's my situation:
I have an x-serve raid with 4x180GB drives in the right side. Not sure why it's built that way, but it is, the way it is. I have only 25 GB of free space left. So I'm trying to figure out my best options. Originally I was thinking of adding 3 more drives 250GB each to the right side, and then merge them together with the main portion of my RAID. However, I'm reading now, there's a change I need to reformat my main slice which is not going to work for me. The type of the file system that I have is MAC OS extended (journaled), which as far I understand means it's HFS+ so I can't add more space on a fly and need to reformat my main slice?
If the answer for that is I do need to reformat, I'd rather start building a new RAID on the left side (say 4x250GB). In this case as far as I understand I'd have 2 standalone raids, which is completely fine, I'm not looking to merge them together, as long as I can use them both for file sharing. So my question is "can I?"
If I can, I guess I'd rather move some stuff from my main RAID to the new one.
Advises, comments are very welcome!

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

Is it possible to add a harddrive to an existing Raid 0 Array?

I have an existing striped raid 0 setup with 2 x 500 GB hard drives.
I just bought 2 more x 500 GB hard drives since i noticed HDD is a bottleneck for my 8 core system.
my question is, can i add the 2 harddrives to my existing raid 0 partition ? (so i have one raid 0 partition of 2 TB )
i tried this, but it didnt work
MacPro-PC:~ kronos$ diskutil listraid
RAID SETS
===============================================================================
Name: Raid 0
Unique ID: 7CD5E941-6AA9-4F47-BE18-2183860B0596
Type: Stripe
Status: Online
Size: 999527743488 B
Device Node: disk4
Apple RAID Version: 2
# Device Node UUID Status
0 disk1s2 D8CB113A-4425-4E4D-AA1C-62118342CA89 Online
1 disk2s2 CC80544C-65A1-4F1D-A26C-F05E2EA92840 Online
===============================================================================
bash-3.2# diskutil addToRaid member disk0 /Volumes/Raid\ 0
Error adding the disk to the RAID: Could not modify RAID (-9960)

You will have to backup all the data and start over to make a new, 4 drive, RAID 0. You can't add drives to RAID 0.

Adding Drives to an Existing RAID 0 Stripe Set

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