dd is so slow on my SCSI disc

Andrew P. infofarmer at gmail.com
Mon Aug 22 20:24:44 GMT 2005

On 8/23/05, Sebastian Pahlke <sp.ibm at gmx.de> wrote:
> Hi all,
> I'm trying to "clean" a disc before selling them:
> dd if=/dev/zero of=/dev/da0
> Do I make something wrong because the transfer rate is only 60932
> bytes/sec??? These are 60 kbytes/sec, slower than my internet connection!!!
> :(
> I tried to increase the block size, with bs=32768 I get 3416071 bytes/sec.
> But this is still very poor. The system is a PIII 800MHz and a SCSI-3 disc
> in single user mode booted from FreeBSD release 5.4 live-cd.
> Any ideas how to analyze this? Thanks in advance!

Hmm, I'd start with increasing block size up to megabytes
and if that doesn't help - I'd try to copy a large file to/from
the disk and measure the speed.

Also, the smartmontools port can tell you much if the drive
supports SMART.

Andrew P.

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