Low HDD tranfer rate with FreeBSD 5.3-Release

[Mike Tancsa]

On Mon, 9 May 2005 14:02:45 -0500, in sentex.lists.freebsd.hackers you
wrote:
>
>Yes, try 64k instead of 8k, and also compare read speeds.  If you have
>the time (could take an hour or so), try "dd if=/dev/ad0 of=/dev/null
>bs=64k", run an "iostat 60" in another window, let the dd run through
>the entire disk, and compare the relative speeds from start to finish.
>
>For the DiamondMax 160, the sustained throughput should be 26MB -> 50MB
>as you go from inner to outer tracks.

Not sure how honest diskinfo is, but the numbers do seem somewhat
reasonable for checking these values.

[releng5-865]# diskinfo -t ad0
ad0
        512             # sectorsize
        40020664320     # mediasize in bytes (37G)
        78165360        # mediasize in sectors
        77545           # Cylinders according to firmware.
        16              # Heads according to firmware.
        63              # Sectors according to firmware.

Seek times:
        Full stroke:      250 iter in   5.641185 sec =   22.565 msec
        Half stroke:      250 iter in   4.381489 sec =   17.526 msec
        Quarter stroke:   500 iter in   7.043785 sec =   14.088 msec
        Short forward:    400 iter in   1.625114 sec =    4.063 msec
        Short backward:   400 iter in   1.524874 sec =    3.812 msec
        Seq outer:       2048 iter in   0.233424 sec =    0.114 msec
        Seq inner:       2048 iter in   0.224814 sec =    0.110 msec
Transfer rates:
        outside:       102400 kbytes in   1.787498 sec =    57287
kbytes/sec
        middle:        102400 kbytes in   2.175933 sec =    47060
kbytes/sec
        inside:        102400 kbytes in   3.416033 sec =    29976
kbytes/sec

[releng5-865]# 

	---Mike
--------------------------------------------------------
Mike Tancsa, Sentex communications http://www.sentex.net
Providing Internet Access since 1994
mike at sentex.net, (http://www.tancsa.com)