Re: Hammer performance

[Michael Neumann]

Matthew Dillon wrote:

:
:Abother strange thing occurs if I "dd" directly to the device:
:
:   dd if=/dev/zero of=/dev/ad4s1d count=20000
:   20000+0 records in
:   20000+0 records out
:   10240000 bytes transferred in 7.361097 secs (1391097 bytes/sec)
:
:Here I only get around 1.4 MB/sec. Shouldn't that me a much higer value?
:
:Regards,
:
:   Michael

    If you do not specify a block size parameter to dd it will be doing
    512 byte writes.  A typical block size is 32k, e.g.:

    dd if=/dev/zero of=/blah bs=32k count=10240

Thanks, that does the trick. Now I get ~100 MB/sec throughput for
sequential reads/writes which I guess is full platter speed.

Regards,

  Michael