I recently setup a Debian Etch box to be used as a file server. There are 4 hard drives, /dev/hda1 for the operation system, /dev/sda1 and /dev/sdb1 which will be in a software raid 1 /dev/md0, and last /dev/sdc1 as a multimedia drive. I have noticed that the real world performance of these drives is not what it could be.

hdparm of:

/dev/hda1:
Timing cached reads: 570 MB in 2.00 seconds = 285.01 MB/sec
Timing buffered disk reads: 138 MB in 3.04 seconds = 45.43 MB/sec

hdparm of:

/dev/md0:
Timing cached reads: 570 MB in 2.01 seconds = 284.12 MB/sec
Timing buffered disk reads: 208 MB in 3.02 seconds = 68.98 MB/sec

hdparm of:

/dev/sdc1:
Timing cached reads: 578 MB in 2.00 seconds = 288.42 MB/sec
Timing buffered disk reads: 182 MB in 3.01 seconds = 60.51 MB/sec

I see above that the write speeds for these disks are significantly higher than what I am seeing when transfering files. For example I will run the following command:

rsync --stats --progress FILE FILE (copied to same partition)

This particular file is roughly 800 MB and the transfer starts out at 27 MB/s and then drops within about 2 seconds to 10 MB/s then steadies around 13 - 15 MB/s for the remainder of the transfer. This seems to occur throughout all of my hard drives. How is it that hdparm reports such high numbers in its test, but when I use rsync to transfer the file the speeds are significantly different?

uname -a:

Linux epsilon 2.6.18-4-486 #1 Wed May 9 22:23:40 UTC 2007 i686 GNU/Linux (Also used 2.6.22)

relevant lspci entries:

00:0d.0 RAID bus controller: Silicon Image, Inc. SiI 3114 [SATALink/SATARaid] Serial ATA Controller (rev 02)
00:11.1 IDE interface: VIA Technologies, Inc. VT82C586A/B/VT82C686/A/B/VT823x/A/C PIPC Bus Master IDE (rev 06)

lsmod | grep sata:

sata_sil 11400 3
libata 87700 1 sata_sil

I have searched throughout the forums for some sort of answer but nothing helped. Thanks for all the help.

-James