Hard disk performance :|

[enko]

3 identical drives in RAID5.

[root@zeus ~]# hdparm -t /dev/sda

/dev/sda:
 Timing buffered disk reads:  134 MB in  3.02 seconds =  44.31 MB/sec
[root@zeus ~]# hdparm -t /dev/sdb

/dev/sdb:
 Timing buffered disk reads:  194 MB in  3.02 seconds =  64.14 MB/sec
[root@zeus ~]# hdparm -t /dev/sdc

/dev/sdc:
 Timing buffered disk reads:  196 MB in  3.03 seconds =  64.70 MB/sec

Speed on the array is okay.

[root@zeus ~]# hdparm -t /dev/md0

/dev/md0:
 Timing buffered disk reads:  268 MB in  3.01 seconds =  88.96 MB/sec

Should I be concerned about the first drive? Why is it so much slower? They're identical. WD 500GB drives.

[Crito]

Not sure if this is the cause of the difference you're seeing, but I read an interesting article today about how firmware affects performance on seemingly identical Seagate drives:
http://www.fluffles.net/articles/seagate-AAK-firmware

Please take care to look at the scale of both graphs, on the left side is the AAE disk with a scale up to 80MB/s, on the right is the AAK disk where the scale goes up to 60MB/s. So where the AAE disk starts at 75MB/s the AAK disk starts at less than 55MB/s, a 20MB/s difference!

[enko]

Thanks! This is what actually made me curious on the speed on my drives when I stumbled upon this.

They all have the same firmware. I did a hdparm -I to get information on all drives, and they all have the same settings.

[Crito]

Might be worth trying smartctl --all /dev/sda to make sure first drive isn't failing.

[enko]

Hmmm. Would this be a cause. Notice the block size (BSZ) of SDA1.

Althouhg, I'm running the hdparm on /dev/sda, not /dev/sda1...

[root@zeus ~]# blockdev --report
RO RA SSZ BSZ StartSec Size Device
rw 256 512 4096 0 488397168 /dev/hda
rw 256 512 4096 63 39086082 /dev/hda1
rw 256 512 4096 39086145 19551105 /dev/hda2
rw 256 512 4096 58637250 1975995 /dev/hda3
rw 256 512 4096 60613245 427778820 /dev/hda4
rw 256 512 4096 0 976773168 /dev/sda
rw 256 512 4096 1 976768064 /dev/sda1
rw 256 512 4096 0 976773168 /dev/sdb
rw 256 512 1024 63 976768002 /dev/sdb1
rw 256 512 4096 0 976773168 /dev/sdc
rw 256 512 1024 63 976768002 /dev/sdc1
rw 512 512 4096 0 1953535744 /dev/md0