Re: [Dump-users] Compression slows dump over gigabit Ethernet

[Stelian P. <st...@po...>]

On Thu, Apr 07, 2005 at 07:44:41PM -0700, Kenneth Porter wrote:

> I tried to add -j2 (compression) to the dump command line but this kicks 
> the expected completion time to over 48 hours, which suggests that the 
> network buffers are starving. Is there some way to avoid this? I thought 
> the megabyte block size would be sufficient but it's not working when 
> compression is enabled.

First of all you should determine if the problem comes from the
CPU (look at system load) or the I/O.

If the problem comes from the CPU, you can, as Helmut says, use
a different compression algorithm.

If the problem comes from the I/O, it could be because you're now
writing in smaller chunks than before (because -b sets the uncompressed
chunk size). In this case, since you're dumping to a file, you could
pipe the output of dump into dd and set a new blocksize for the output:
	dump ... | dd of=1024 > ${OUTDIR}/sda1/dump

Stelian.
-- 
Stelian Pop <st...@po...>