Hi,
This is more a RAID5 question than an XFS one, but perhaps it's
relevant anyway - I'm not sure - I'm a bit of a novice at RAID5.
We have just added to our machine to make it 8 60G ATA/100 disks in a
XFS+SoftwareRAID5 setup. /proc/mdstat tells me that it's going to
take 700+ minutes to build the parity data for the full 480G. It's
running at a speed of ~1300K/sec...
Is this about the length of time I'd expect? Seems a lot... :-/
It's a dual celeron 500 system and both CPUs seem to be flat out running
100% system time doing raid5syncd and raid5d. It's running cvs kernel from
yesterday (sunday).
When we had 4 of these 60G disks doing RAID5+XFS I think it took
about 180 minutes to reconstruct all the parity data which was a more
reasonable time.
Am I just CPU speed limited here?
Is there any rule of thumb that governs these rebuild times?
Something depending upon number of disks in the raid set perhaps.
When it boots it prints:
Mar 19 17:26:49 jersey kernel: raid5: measuring checksumming speed
Mar 19 17:26:49 jersey kernel: 8regs : 674.400 MB/sec
Mar 19 17:26:49 jersey kernel: 32regs : 455.600 MB/sec
Mar 19 17:26:49 jersey kernel: pII_mmx : 1113.200 MB/sec
Mar 19 17:26:49 jersey kernel: p5_mmx : 1180.000 MB/sec
Mar 19 17:26:49 jersey kernel: raid5: using function: p5_mmx (1180.000 MB/sec)
which looks like 1GB/sec which is fast - more like 480 seconds for
480G of disk than 11 or 12 hours :)
Anyway - like I said, I have no idea what is "normal" for RAID5 so any
hints are much appreciated.
cheers,
robin
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