[mythtv-users] OT Hardware RAID 5 Recommendations

Mike Poublon poublon at geeksoft.dyndns.org
Tue Dec 12 19:25:08 UTC 2006

I'm using software raid 5 on an athlon xp 1900 using 4 120Gb IDE drives 
and just tested the write speed in a box with 768MB of ram

# time dd if=/dev/zero of=test bs=1M count=1024
1024+0 records in
1024+0 records out

real    0m19.959s
user    0m0.012s
sys     0m6.716s

# time dd if=/dev/zero of=test bs=1M count=2048
2048+0 records in
2048+0 records out

real    0m42.320s
user    0m0.040s
sys     0m13.881s

Yeilding about 49 MB/s write

Read speeds are about 32 MB/s (using the same tests just swapping the in 
and out parameters)

While watching the output of top, the software raid process never really 
gets above 10%...


> Brett:
> Thanks, I'm looking for RAID5 which requires that a parity bit be set
> across all of the disks.  This requires a fair bit of horsepower.
> RAID1 is (if I remember correctly) simply a mirror, which would be a
> waste of disk space.  On that point, I'm not sure if software RAID
> does level 5.
> George

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