RAID5 array Ready for Rebuild

Solution 1:

This is a bit crazy... A Smart Array P600 PCI-X RAID controller (circa 2005)?!? 25 disks? RAID 5? Is this an HP MSA70 enclosure? Is probably not the HP D2700?

"Ready for Rebuild" is about the worst array status message you can receive on an HP ProLiant system. This indicates that the logicaldrive can't finish its rebuild because there's trouble reading from a partner or dependent drive(s). Usually this means that you have a failed disk and a failing disk. This is also known as an Unrecoverable Read Error (URE).

Please see the following:

RAID 1 fault " Status Ready for Rebuild : Rebuild Percentage Complete 0%"

HP Proliant ML350 G5 SAS HDD

Force LUN in a HP Smart Array to rebuild

24 disks in RAID5 is stupid. That's not your fault. 25 disks is, though. It's too many drives for RAID5, even with the 10k RPM enterprise disks you have. Losing your spare in order to add 300GB of space was a bad move because of the I/O and time impact of expanding such a large disk group. It hits all the disks and would have taken a very long time. Too much risk and exposure involved.

There is a slight chance that you are running into a controller firmware issue or configuration limitation. The last release of firmware for that controller was in 2009. Old gear plus a really abnormal configuration like yours are edge cases that require some work to fix. This could also be a problem with the enclosure.

• Do you have good backups?
• Are you in a position to bring firmware of all components up-to-date?
• Can you power cycle everything here and watch the system POST messages closely to read the RAID controller output?
• You may be able to jump-start the rebuild process, assuming there are no real READ errors on the drives.

So it's counter-intuitive, but a power-off, wait and power-on may be your best bet.
It could also be your worst bet, so hopefully you have backups. :(

Solution 2:

An old post, i know, but might be helpfull for others. My P410i does this most of the time, when i replace a disk. The new disk initializes, and then it says Ready to rebuild, but nothing happens. When it does this, i unplug the power for the disk i just replaced, that it wouldn't rebuild. Wait 10-15 secs, and replug it, then rebuilding starts. I'm running a Raid 50 with 8 disks on it - think it is on 6 years and counting, and have had 3 faulty disks over time - But rebuilded 6 times, because i replaced with a temporary disk, until i got the right spare.