From: Janik, Jesse (J.Janik@TriCorInd.com)
Date: Fri Mar 14 2003 - 17:15:34 EST
I've looked through several archives to get this far, but am stuck at this
point.
I've got the command to here:
/usr/sbin/ufsdump $1uf - $i 2>> ${LOG_FILE} | /usr/local/bin/ssh -l sysadmin
mars "dd obs=8192 of=/dev/rmt/0cn" > /dev/null 2>&1
(This command is started as root, $1=0 in most cases, and $i is the file
systems)
The problem is that using rsh, the transfer rate is around 3,000KB/sec,
using ssh its only around 600KB/sec.
This means that a dump that usually takes an hour, now takes 4.5 To cut
down on some time I've tried several output block sizes, with 8192b being
the best for dd. Then I mucked around with a suggested "buffer" which is
the 102400k dd command in:
/usr/sbin/ufsdump $1uf - $i 2>> ${LOG_FILE} | /usr/local/bin/ssh -l sysadmin
mars "dd obs=102400k | dd obs=8192 of=/dev/rmt/0cn" > /dev/null 2>&1
Which was supposed to help the actual writing to the mammoth tape drive
because supposedly without that buffer the tape drive can cause massive
slowdowns. It resulted in a longer backup! (Now I'm trying a 1024000k
buffer at this moment in time because system memory allows).
Just to let you know right now I can't switch to ssh using blowfish because
government doesn't allow.
The question is this, am I wasting my time with the "buffer" dd? Did I miss
a good block size with the writing dd? Is there something else I can do to
speed up the whole process? I understand that the ssh is a serious
bottleneck, but would like to streamline this as much as possible to
minimize the chance for failure and reduce network crippling time.
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