dd is so slow on my SCSI disc

Dmitry Mityugov dmitry.mityugov at gmail.com
Tue Aug 23 06:31:19 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!

In addition to other replies, there are drives that test their blocks
on first write to them. This makes first write operations slow but
that's normal - subsequent writes to the same spots on the drives
should be fast.

Dmitry Mityugov, St. Petersburg, Russia
I ignore all messages with confidentiality statements

"We live less by imagination than despite it" - Rockwell Kent, "N by E"

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