How to Build a RAID Mirror Without a Re-Format

Authored by: MDhaliwal on Monday, August 30 2004 @ 04:55 pm MDT

I'm about to try this right now! I have my G5 Xserve booted in target disk
mode off my PowerBook and have created a NetBoot Install image of the
Xserve, so if it bombs, I can restore directly off of the image I created. I'll
post in how it goes!

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Authored by: Anonymous on Tuesday, August 31 2004 @ 11:14 am MDT

Rebuild RAID in the background?? I didn't think this was possible with the
software RAID! I've had to boot up from the CD and do disk utility from there
to rebuild a degraded RAID. When I've tried to do this while booted up from
the HD it won't let me. (unfortunately it's been a while since I last tried this
so i dont remember the error messages). How do i do it in the background?
this would have saved me many many hours of downtime rebuilding a 120G
mirror.

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Authored by: davidr on Friday, September 24 2004 @ 02:41 pm MDT

Worked perfectly on a friend's G5, thanks!

10.3.5 will rebuild automatically once the RAID rebuild is started. I discovered
this by accidentally quitting Disk Utility part-way through the rebuild, when I
re-opened it the progress window popped up immediately...

One question though, when rebuilding form the CLI, you mention the RAID
device name. Would this be the name of the drive you are mirroring from?

'diskutil repairMirror (RAID device name) (Bad slice) (Good member) (New
member)'

BTW, on a 1.6ghz G5 with 2gb of RAM, and 2 80gb SATA drives with about
45gb of data on them the rebuild took 45 minutes.

Cheers,

Dave

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Authored by: chiefgeek on Tuesday, October 19 2004 @ 09:12 pm MDT

Thanks for the excellent article. I have used this half dozen times since it was posted. In most cases, I've advised my customers to purchase a stock G5 with 160 drive and replace with two Maxtor SATA 250s ($200 from MicroCenter).

It appears as though the time it takes to remount the partition is roughly 30 seconds even on a G5.

I've done a couple of the configs remotely without problem.

Takes about 2-2.5 hours to rebuild the mirror on a 250 with 50gb + worth of data. I'm just starting the rebuild of my drives (90gb on a 160) so we'll see how it does.

Thanks again.

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Authored by: pixpixpix on Friday, October 22 2004 @ 03:48 pm MDT

I am running OS 10.3.5 on a G5 with external FW800 LaCie twin 305GB drives as RAID 1. After a freeze I had to shut down the machine and on restart got an unrecognixzable disk in the RAID array, so shut the machine down and went to bed.

This morning it boots fine and DiskUtility shows the RAID array with both disks degraded.

But...I checked the Raid status with terminal as suggested in

http://docs.info.apple.com/article.html?artnum=106987

and it says both disks have status OK

Name: Hydra
Unique ID: Hydrab2e9e566214a11d99823000a95afef40
Type: Mirror
Status: Degraded
Device Node: disk6
-------------------------------------------------------------
# Device Node Status
-------------------------------------------------------------
0 disk5 OK
1 disk2 OK
-------------------------------------------------------------

I also ran Disk Warrior to rebuild the directory and ran repair in Disk Utilities and they checked out OK


Is it possible there isn't a problem? or if not how would I find a problem?

Apple notes that with the OS X Server it is possible to ignore the degraded status in some cases, implying it might be mistakenly reported

http://docs.info.apple.com/article.html?artnum=107406

anyone ever heard of this? any suggestions

thanks

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Authored by: Anonymous on Tuesday, December 21 2004 @ 06:17 pm MST

I think it's a good thing! .

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Authored by: ahancock on Wednesday, December 29 2004 @ 03:25 pm MST

OK,

So when attempting the first step on this drive w/ partitions, I get
Error enabling disk to RAID Disk is not suitable for enabling RAID (-9694)

Wonder if there is a way around this.


oh, and the link to the manpage has changed & can now be found at
http://developer.apple.com/documentation/Darwin/Reference/ManPages/man8/diskutil.8.html

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Authored by: andrina on Wednesday, February 02 2005 @ 11:51 am MST

Anyone have any statistics on drive performance during a rebuild? We have a
bit of a high usage server (editing server) that will be undergoing a raid
rebuild - I need to know if I should tell our editors to not bother working for
the hour it takes to rebuild, or to proceed as normal.... Any experience
anywhere?

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Authored by: ed209 on Monday, May 30 2005 @ 10:23 pm MDT

The chase: I have removed two disks from a 10.3.9 software mirror RAID
set using the 10.4GM diskutil.
One now has a partition map with slice 4 of type "Apple_RAID", the
other disk has slice 4 of type "Apple_RAID_OfflineV2". How do I get one
or both back to being normal Journaled HFS+ volumes without wiping their
data?

At the very least, I need technical doc for Software RAID - a google for
Apple_RAID
yields absolutely no hits - nor does a search on Developer Connection.

---
Disclaimer: I know what I did here was wrong and that I need to go back
to a backup. No need for anyone to waste their time on a helpful post to
tell me this - but thanks in advance for the thoughts anyway.

The detail:
It started out as a sunny day in Sydney, Australia. Life seemed good.
The night before I had upgraded a 2x2Ghz G5 PowerMac from Panther Server
to Tiger Server successfully.
Kerberos, AFP, DHCP, DNS were all smoothly up and running, as was Samba,
Apache and even JBoss.
I had gotten IMAP and POP running where others had failed - Apple
includes an invalid TLSNames attribute in the cyrus config file that
needs to be deleted to allow mail delivery to kick off.
The jewel in the crown... My HP5510 printer was even behaving properly
with the new server and print serving was finally working again using
IPP - it had been broken under Panther.

So, I thought, before I go to bed I had better just check the world is
good with disk utility.
Alas, I found that my software mirror was in a 'degraded' state. I had
forgotten that before I did the Tiger upgrade I had attempted to split
one drive from the array and leave it powered off Just In Case.

The array failed to boot with the missing disk, so I had reluctantly
plugged it back in, intending to rebuild the array before the Tiger
upgrade. Mistake #1 - I forgot to do so.

In any case, to its credit, the Tiger Server installer happily upgraded
the OS on the degraded array and left it in the same state.

So, I thought, I know I can't repair that array volume because it is the
startup disk. I'll have to reboot with the Tiger Server DVD and rebuild
the array then.

Once booted with the Tiger DVD, I found Disk Utility to be a little
whacked. (I later learned that there is a difference between Panther
RAIDsets and Tiger RAIDsets but at the time I was ignorant). It was
unable to rebuild the array or do anything with the existing
configuration - except show little padlock icons next to each disk. I
now attribute ths to differences between Tiger and Panther RAID.

So, I thought, this can't be right. And off I trundled into the Terminal
app to hunt down the problem with Disk Utility.

I determined my only option was to attempt to rebuild the RAIDset using
diskutil repairMirror <mirrorname> <offlinediskname>.
I kicked this off - no dice.
Figured it didn't 'take' - so kicked it off again.
Nothing. No activity whatsoever. Mistakes #2 and #3 had just happened.

Figured it might be like some old Promise RAID implementations I've used
in the past and that rebuild might start only on reboot.

Rebooted the system (that had never previously failed to boot).
It failed to boot - with a big "no" symbol where the Apple normally is.
(That's 'no' as in 'no smoking' but without the cigarette)

So, I thought, time to boot the server install DVD again.
Once more, the graphical Disk Utility was useless. Back to terminal.
Sure enough, a quick diskutil showRAID revealed that there was one
"online" disk, one "offline" disk and two unknown disks - a total of
four drives - now involved in my 2-physical-disk mirror RAID set.
No amount of checking, removing, or otherwise could do anything to get
rid of the "unknown" disks from the RAIDset - I now suspect these were
created by trying to rebuild a 10.3 array in 10.4 Disk Utility.

On a whim (mistake #4) I thought I'd try to rebuild the mirror again,
having no real other option, so I fed diskutil the disk marked as
'offline'. Lo and behold, the mirror began to rebuild. A quick "diskutil
checkRAID" confirmed progress was being made.
Sometime between 80% and 100% something bad must have happened
because
when I came back in the morning I found that the rebuild had terminated
normally, but there was no change in the mirror status - it was still
degraded, with one disk offline, one online, and two phantom unknown
disks.

Finally, in desperation I decided to split the offline disk from the
array using diskutil removeFromRAID. It worked!!!
The array was still all funky with those other drives so I also then
removedFromRAID the online drive, thus completely destroying the RAIDset
- but at least those phantom disks are gone. Mistake #5

Now I figured, I could simply add either (but preferably the formerly
online) disk back into a new array using diskutil enableRAID mirror
diskname, then rebuild it with repairMirror feeding it the other.

Unfortunately, enableRAID requires its disk to be mounted. A quick
diskutil list showed me neither of my offline mirror halves were indeed
mounted.

So, I thought, a quick diskutil mountDisk will fix my last problem.
Mistake #6. It turns out that the 4th slice of each of the individual
mirror disks now have non standard partition types. One is Apple_RAID.
The other is Apple_RAID_OfflineV2.

However the rest of the disk partitions look good and I know these disks
have not been written to since I started this whole messy process.

My belief is that incompatibilities between Apple_RAID v1 and v2 exists
and that I am partially a victim of this problem - largely just my own
stupidity and lack of caution.

So, the question is, does anybody out there know about how I can convert
these disks back to standard bootable drives - or even where to find
details on the partitioning scheme used by Apple. And ideally, how can I
overwrite the drive partition map data but not mess up the data?

I since found the Monster Disk Technote and tried using pdisk to change
the ContentHint for the Apple_RAID partition back to Apple_HFS.
No dice - can't verify the volume in Disk Utility.


It started off as such a nice day...

Thanks for reading such a longwinded post. All help accepted humbly and
gratefully.
Marc

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Authored by: reppep on Tuesday, July 26 2005 @ 01:01 am MDT

No joy for me. I booted from the 10.4 Server CD-ROM, and ran Disk Utility
from the menu. enableRAID fails to shrink ('grow') the volume, although
there's plenty of free space.

Here's what I saved off before booting back to normal:

-sh-2.05b# diskutil list
/dev/disk0
#: type name size identifier
0: Apple_partition_scheme *115.0 GB disk0
1: Apple_partition_map 31.5 KB disk0s1
2: Apple_Driver43 28.0 KB disk0s2
3: Apple_Driver43 28.0 KB disk0s3
4: Apple_Driver_ATA 28.0 KB disk0s4
5: Apple_Driver_ATA 28.0 KB disk0s5
6: Apple_FWDriver 256.0 KB disk0s6
7: Apple_Driver_IOKit 256.0 KB disk0s7
8: Apple_Patches 256.0 KB disk0s8
9: Apple_HFS www 114.9 GB disk0s10
/dev/disk1
#: type name size identifier
0: Apple_partition_scheme *149.1 GB disk1
1: Apple_partition_map 31.5 KB disk1s1
2: Apple_Driver43 28.0 KB disk1s2
3: Apple_Driver43 28.0 KB disk1s3
4: Apple_Driver_ATA 28.0 KB disk1s4
5: Apple_Driver_ATA 28.0 KB disk1s5
6: Apple_FWDriver 256.0 KB disk1s6
7: Apple_Driver_IOKit 256.0 KB disk1s7
8: Apple_Patches 256.0 KB disk1s8
9: Apple_HFS www-spare 115.9 GB disk1s10
10: Apple_HFS 33gb 32.9 GB disk1s12
/dev/disk2
#: type name size identifier
0: Apple_partition_scheme *71.6 GB disk2
1: Apple_partition_map 31.5 KB disk2s1
2: Apple_Driver43 28.0 KB disk2s2
3: Apple_Driver43 28.0 KB disk2s3
4: Apple_Driver_ATA 28.0 KB disk2s4
5: Apple_Driver_ATA 28.0 KB disk2s5
6: Apple_FWDriver 256.0 KB disk2s6
7: Apple_Driver_IOKit 256.0 KB disk2s7
8: Apple_Patches 256.0 KB disk2s8
9: Apple_HFS 71gb 71.5 GB disk2s10
/dev/disk3
#: type name size identifier
0: Apple_partition_scheme *232.9 GB disk3
1: Apple_partition_map 31.5 KB disk3s1
2: Apple_Driver43 28.0 KB disk3s2
3: Apple_Driver43 28.0 KB disk3s3
4: Apple_Driver_ATA 28.0 KB disk3s4
5: Apple_Driver_ATA 28.0 KB disk3s5
6: Apple_FWDriver 256.0 KB disk3s6
7: Apple_Driver_IOKit 256.0 KB disk3s7
8: Apple_Patches 256.0 KB disk3s8
9: Apple_HFS 232gb 232.7 GB disk3s10
/dev/disk4
#: type name size identifier
0: Apple_partition_scheme *2.6 GB disk4
1: Apple_partition_map 31.5 KB disk4s1
2: Apple_Driver_ATAPI 4.0 KB disk4s2
3: Apple_HFS Mac OS X Server Install Disc 2.6 GB disk4s3
/dev/disk6
#: type name size identifier
0: untitled *467.0 KB disk6
/dev/disk7
#: type name size identifier
0: untitled *95.0 KB disk7
/dev/disk8
#: type name size identifier
0: untitled *95.0 KB disk8
/dev/disk9
#: type name size identifier
0: untitled *95.0 KB disk9
/dev/disk10
#: type name size identifier
0: untitled *219.0 KB disk10
-sh-2.05b# diskutil enableRAID
Disk Utility Tool
Usage: diskutil enableRAID [mirror|concat] [Device Node|Device Identifier]
Convert a single filesystem disk into a degraded mirror or concatenated RAID
set.
This will not work with all disks. Filesystem must be mounted and
shrinkable.
(i.e. Journaled HFS+, or its derivates). There must be enough room
to insert RAID information. Ownership of the affected disk is required.
Enabling RAID is an inherently dangerous operation. Please make
backups
of all affected data before proceeding.
Example: diskutil enableRAID mirror /Volumes/Target
-sh-2.05b# diskutil enableRAID mirror /Volumes/www
changing filesystem size on disk 'disk0s10'...
Attempting to change filesystem size from 123376680960 to 123387248640
bytes
Filesystem grow failed, 1
Disk Management could not shrink the filesystem to fit the new RAID headers
Error enabling disk to RAID Invalid request (-9998)
-sh-2.05b# diskutil enableRAID mirror /dev/disk0
The target disk must be a volume, not a whole disk

Disk Utility Tool
Usage: diskutil enableRAID [mirror|concat] [Device Node|Device Identifier]
Convert a single filesystem disk into a degraded mirror or concatenated RAID
set.
This will not work with all disks. Filesystem must be mounted and
shrinkable.
(i.e. Journaled HFS+, or its derivates). There must be enough room
to insert RAID information. Ownership of the affected disk is required.
Enabling RAID is an inherently dangerous operation. Please make
backups
of all affected data before proceeding.
Example: diskutil enableRAID mirror /Volumes/Target
-sh-2.05b# diskutil enableRAID mirror /dev/disk0s10
changing filesystem size on disk 'disk0s10'...
Attempting to change filesystem size from 123376680960 to 123387248640
bytes
Filesystem grow failed, 1
Disk Management could not shrink the filesystem to fit the new RAID headers
Error enabling disk to RAID Invalid request (-9998)
-sh-2.05b# df -hl
Filesystem Size Used Avail Capacity Mounted on
/dev/disk4s3 2.6G 2.5G 94M 96% /
/dev/disk6 467K 11K 433K 2% /Volumes
/dev/disk7 95K 64K 27K 70% /private/var/tmp
/dev/disk8 95K 13K 78K 14% /private/var/run
/dev/disk3s10 233G 146G 87G 63% /Volumes/232gb
/dev/disk2s10 71G 40G 31G 57% /Volumes/71gb
/dev/disk1s10 116G 52M 116G 0% /Volumes/www-spare
/dev/disk1s12 33G 34M 33G 0% /Volumes/33gb
/dev/disk9 95K 18K 73K 20% /private/tmp
/dev/disk10 219K 29K 180K 14% /private/var/db/netinfo
/dev/disk0s10 115G 40G 74G 35% /Volumes/www
-sh-2.05b# diskutil
Disk Utility Tool
Utility to manage local disks and volumes.
Most options require root access to the device

Usage: diskutil <verb> <options>
<verb> is one of the following:
list (List the partitions of a disk)
information | info (Get information on a disk or volume)

unmount (Unmount a single volume)
unmountDisk (Unmount an entire disk (all volumes))
eject (Eject a disk)
mount (Mount a single volume)
mountDisk (Mount an entire disk (all mountable volumes))
rename (Rename a volume)

enableJournal (Enable HFS+ journaling on a mounted HFS+ volume)
disableJournal (Disable HFS+ journaling on a mounted HFS+ volume)

verifyVolume (Verify the structure of a volume)
repairVolume (Repair the structure of a volume)

verifyPermissions (Verify the permissions of a volume)
repairPermissions (Repair the permissions of a volume)
repairOS9Permissions (Repair the permissions for the current
Classic boot volume)

eraseDisk (Erase an existing disk, removing all volumes)
eraseVolume (Erase an existing volume)
reformat (Reformat an existing volume)
eraseOptical (Erase an optical media (CD/RW, DVD/RW, etc.))
zeroDisk (Erase a disk, writing zeros to the media)
randomDisk (Erase a disk, writing random data to the media)
secureErase (Securely erase a disk or freespace on a volume)

partitionDisk ((re)Partition a disk, removing all volumes)

createRAID (Create a RAID set on multiple disks)
destroyRAID (Destroy an existing RAID set)
checkRAID (Check a RAID set for errors)
enableRAID (Convert a disk to a degraded RAID mirror set)
convertRAID (Convert a RAID 1.x (pre-Tiger) to a RAID 2.x (Tiger))
updateRAID (Update the settings of an existing RAID)
addToRAID (Add a spare or member disk to an existing RAID)
removeFromRAID (Remove a spare or member disk from an existing
RAID)
repairMirror (Repair a damaged RAID mirror set)

diskutil <verb> with no options will provide help on that verb

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Authored by: Anonymous on Saturday, January 14 2006 @ 12:45 am MST

I managed to efficiently turn my boot disk into a RAID group without any
down time or risk, but I had to modify the procedure described here because
using the "enableRAID" command didn't work for me.

The basic idea is to turn the new disk into an empty RAID slice and then copy
the boot disk into it. Boot up into this one-disk RAID group, and then turn
the original boot disk into the second RAID slice. This isn't any more work
than the method described, because the first copy is equivalent to making a
backup. In more detail:

1) I started by using Disk Utility to erase the "mirror" drive I was adding. I
ran "diskutil enableRAID mirror /Volumes/MirrorDriveName". Note that
diskutil uses whatever name you've given the mirror drive as the name of the
RAID group, and you can't change this later.

2) I then quit and restarted Disk Utility, clicked on the new drive and used the
Restore option to copy the boot disk onto the single RAID slice I had created.
Note that the new drive has two entries in the list of volumes (slice name and
RAID group name) and only one of these has the Restore option.

3) When the copy was complete I selected the new one-disk RAID group as
my boot disk in System Preferences and rebooted.

4) Now I was booted into the one-disk RAID group and I again used the
graphical version of Disk Utility and dragged the old boot disk into the RAID
group. This erased the old boot disk and started the mirror "repair".

The repair copied the mirror disk onto the original disk, and a few hours later
I had an intact mirrored RAID group as my boot disk.

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Authored by: sphen on Wednesday, February 15 2006 @ 02:05 pm MST

I typed up a pdf file with my experiences with tiger server building on the post
from above. ideally it doesnt involve much downtime at all. just requires a
reboot and the server can be headless and remote from your location.

http://escamuel.org/tiger_raid.pdf

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