Slow array rebuild on ML750

[Kevin Boyle_1]

We have a ProLiant ML750 with 11 drives configured as a single RAID 5 array, plus a hot spare, split into two logical drives (512 and 110 GB approx). One of the drives has failed and the hot spare has kicked in and the array has started to rebuild itself. However, this happened on Tuesday evening at 9.30pm (London time) and, as of 9.30am this morning (Thursday), the array had only rebuilt 45%. We have since upped the rebuild priority to 'High' and at 4.30pm the rebuild was at 60%. I know that we have a large capacity array, but surely this cannot be normal? Are there any other settings we can change to increase the rebuild rate?

The server is running Windows 2000 Advanced Server (SP3) and SQL Server 2000 Enterprise (SP3a). The drives are 72GB Ultra3 devices, attached to a Smart Array 4250ES controller (firmware 1.44)

Any help would be appreciated.

[Sunil Jerath]

Hello Kevin,
Even though you have changed the rebuild priority to High during the rebuild process it's not going to make any different till the next reboot is done. Also there is a newer firmware of the controller:

http://h18007.www1.hp.com/support/files/server/us/download/19135.html

Usually it takes between 20/25 minutes per GB.

Regards,

[Kevin Boyle_1]

Sunil,

thanks for the reply. I wasn't aware that changing the priority didn't happen immediately, but it explains why things didn't speed up at all. We will have to decide what the default setting should be on all our servers for the future. We will also ensure that we have the latest firmware for all controllers.

We ended up turning off SQL Server overnight and the rebuild finished at around 3 a.m. this morning. Looking at the Event Log, the 110 GB drive rebuilt in around 3 hours - how does that fit in with your figure of 20 mins per GB?

Regards,

Kevin

[Sunil Jerath]

Hello Kevin,
The timing I stated depends typically upon the HW configuration. The slower the HW the longer it takes for the array to rebuild. The current applications also take over the resources so that would make a difference as well. If you faster CPU and more RAM then it speeds up the process.

Regards,