Re: [Dump-users] Slow dump

[Kenneth P. <sh...@se...>]

--On Thursday, December 09, 2004 11:01 AM -0800 Kenneth Porter 
<sh...@se...> wrote:

> Very interesting. With QFA and -j9 to local files I got about 3-4 MBps.
> Turning off those options and going back to the remote file I'm getting
> 8-9 MBps. (Woot!) I'm now trying to isolate which of those is the problem.

Looks like it was the j9 compression. I had originally put that in thinking 
that it would help compensate for slow network bandwidth.

So the fixes so far:

Remove j9.
Switch from smbfs to cifs.
Specify explicit buffering in the mount and dump commands to maximize 
throughput.

The mount command looks like this:

mount //bigiron/BigBackup /mnt/Backup -t cifs -o
user=ken,password=xxxx,forcedirectio,wsize=65536,rsize=65536

(forcedirectio is a no-op with my kernel but there's experimental support 
for it in development kernels that should further reduce buffer-to-buffer 
copies.)

The dump command is now this:

BLOCKSIZE=1024
dump 0u -b ${BLOCKSIZE} -Mf ${OUTDIR}/sda1.dump -B 1000000 /mnt/sda1 -Q 
${OUTDIR}/sda1.qfa