Why it's good to have a BBU

mikesm

Limp Gawd
Joined
Mar 2, 2005
Messages
178
So my storage server had been plugging along pretty well for sometime now. It's has 8 GB RAM and Q6600 (I do commmercial processing on the NAS too) CPU and has 2 volumes, an 8 drive 1TB Hitachi RAID6 array, and a 7 drive WD20EADS RAID6 array connected via an HP SAS expander to an adaptec 5085 SAS controller.

My NAS complained about a battery failure, and I pulled the battery pack from the array (to verify that I was ordering the proper batteries). They will get here monday.

Well, it's late and I leave the battery pack out and go to bed. The next morning, SageTV can't play recordings. So I check the NAS and the power is off. Not only is the power off, but the UPS won't power up. It's dead.

I bring the system up and I get an alarm from the raid controller indicating the arrays are damaged... Ugh. They automatically start rebuilding, and the Hitachi array comes back up fine, but the WD array is damaged and takes almost 2 days to REBUILD (the Hitachi took about 24 hours to do a BUILD/VERIFY).

I boot the sysrem and windows server does a disk check that also runs over night. All the files on the Hitachi array were fine. But I lost about 50 files from the WD array. Not too bad, as I have about 8 TB of recordings there.

I'm not exactly sure what happened, but I had previously thought a BBU was not really worth it because I had it connected to a good UPS. But if the UPS fails, the BBU probably would have avoided my data loss and the associated downtime.

I had thought to myself that if I had lost the array I would have rebuilt the system with opensolaris and ZFS, but it appears I have some slight data loss and a few bad stripes (that I can't fix because I don't have enough storage to offload the files on the WD array so I could reinitialize it).

Anyways, not a bad outcome. The last time I had a serious hardware failure I lost ALL the data on my linux RAID6 based NAS, and that prompted me to go to hardware raid under windows. I miss the performance of the linux NAS, but I prefer fewer hassles these days to performance...

Hopefully this will be helpful to you guys...
 
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