Re: Hammer performance

[Michael Neumann <mneumann@xxxxxxxx>]

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