We have a few servers that are still running from being upgraded from the 10.2 and 10.3 days. Most all are running Tiger server, with one or two running Leopard.
Since all our XServe G4s run with dual mirrored pairs, we have quite a few of these software RAID sets.
The trick is that if a mirror pair becomes degraded, your server is now vulnerable because 10.4 disk utilities will not allow you to rebuild a v.1 raid set. You MUST convert the RAID set to v2 before it can be restored.
Unfortunately, the convertRAID verb for the command line diskutil, had some issues. Specifically if your drives had the OS 9 Drivers installed on them, or there wasn’t enough room to shrink the current partition, then the convertRAID operation would destroy the partition map of your disk.
As a result, the only way to get these volumes converted to v2 was to take the volume offline and run a Dusk Utility Restore operation from the v1 pair/disk to a new v2 pair/disk.
Since we have a handful of v1 RAID pairs that are the boot volume, being able to take a server down long enough to perform this operation is sometimes difficult.
The fine folks at SoftRAID have added a new feature to their latest version that allows you to convert RAID sets from the Apple RAID to a SoftRAID version and back. We’ve tested converting from v1 to SoftRAID format then to v2 and it works well. We had some strange behavior from the partition maps, but Mark James and the engineering staff gave us some tips on what to look for and this cleared those issues up. If you can’t run hardware RAID, get yourself a copy of SoftRAID.
As a lark, we also booted the server we used to test all of this on with Leopard Server and tried the diskutil convertRAID command to see if Apple had fixed that operation and it hallelujah it worked!
It even turned a single disk degraded v1 raid into a single member v2 raid set that could easily have another drive added to it for bringing it back to full redundancy. Good news this is as we won’t have to have a server with a boot volume that needs converting down for longer than it takes to boot from Leopard (a external FireWire drive of course), run the conversion, then reboot.
If you are running a server and do not have fully redundant (RAID is NOT backup) boot and data partitions, get thee to a store and buy another drive and add it in. The diskutil enableRAID command also works very well on a single disk.
[…] To be clear, SoftRAID isn’t a perfect panacea. The primary issue I’ve observed is that, as is the case with all of its other third-party developer ‘partners’, Apple seemingly provides SoftRAID no advance notice of O/S and application patch releases…some of which inevitably wreak havoc (to a greater or lesser degree) with the program and/or its all-important RAID driver. Since OS 10.3 is effectively mothballed, I feel pretty safe running SoftRAID v3.5.6 on it. However, for SoftRAID-converted OS 10.5, I’ll just need to be sure to make it a habit to wait a few days and monitor user groups for early-adopter angst before downloading any Apple-sourced updates. I’ll also need to hope that SoftRAID doesn’t ever go out of business (although in that case I could always regretfully convert my RAID set back to Apple v2 format). […]