Using DUMP on Exabyte on Sun 3/280

[Randal Schwartz]

In article <4943 at brazos.Rice.edu>, canon!laukee at nsfnet-relay (David Lau-Kee) writes:
| I don't know about the 64b = 32k blocking factor suggested previously for
| dumping to a pipe, but it is certainly reasonable for getting to the
| exabyte (since it is a full mutiple of 8192), however it does look like
| 32k is well below the 63k SCSI bus transfer maximum.

Yes, I've done dumps at 63k, but it panic'ed one of our Sun3's for running
out of buffer space (something else was going on at the time that probably
contributed), and I cranked the number back to play it safe.  I haven't
had any problems since then, *or* enough "spare time" to try raising it
back to 63k to see if anything ever breaks again.

| There are probably good reasons for wanting to pipe into an rsh to dd onto
| the exabyte, but for dumping across a network I usually go for specifying a
| remote tape unit to dump.

I've got the script designed to work with both our Suns and our Microvaxes
(blech!) and the microvax /dev/rmt *seems* to have problems talking to the
scsi.  Once again... if I had the time (does *any* SA ever have time?)
I'd try to work out exactly what broke and fix it.

| Note the 120 second sleeps between filesystem dumps.  This is because the
| exabyte pauses for several seconds after a filemark has been written.  The
| Sun driver has a pause built in to prevent operation during this period,
| but in my experience this has proved insufficient.

Yeah, I found that out "the hard way" too.  Started first with no delay,
then 60 seconds, then 120 seconds, which is my current value.  Been using
that for a few months.

|								  Also note
| that multi tape dumps will not work since I am not recalculating tape
| remaining between files (but with 2.04 Gig and only 7 machines I'm not too
| bothered!).

Yeah, I have a whole bunch of support now for taking the 146 "worthwhile"
filesystems and mapping them into tape collections that are all under 2G.
I also have scripts to stat the current sizes to find out if the level 0
tape collections can be further collected.  (All in Perl, of course... :-)

Just another Perl hacker, exabyte user, and sysadmin,

/=Randal L. Schwartz, Stonehenge Consulting Services (503)777-0095 ==========\
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