Dumping over NFS

[Joe Angelo]

in article <6378 at swan.ulowell.edu>, arosen at hawk.ulowell.edu (MFHorn) says:
> 
> Thanks.
> 
> This has probably come up before, but are there any ways to speed up [tar]
> dumps of remote machines through NFS (besides 'get a faster machine/tape
> drive')?  More specifically, I log on to an 11/785 running Ultrix 2.0, and
> type "tar c /nfs".  /nfs is a remote partition mounted from a uVax II/GPX
> (also running 2.0).  It dumps with no problems to a tu81, but it takes 2
> hours for one tape (neither machine had any users at the time).

Why not issue the tar command on the remote system via rsh and a
dd conversion of block size? Oh, I forget the dd block size to
use (see any of the sun application installation manuals) .. Try something
like:

	rsh $remote -n '(cd / ; tar cbf YY - . | dd obs=XX ibs=XX)' > /dev/rmt8

NFS is gonna be slow no matter how you cut it simple because your local
tar command will have to stat & read every remote file & directory OVER
the network. The only things to check here are to make sure that your
remote machine's tar command uses some default blocking factor (YY) and
that the obs/ibs blocks used in dd (XX) match the blocking factor of
your tape drive [and network?].  Of course, if your remote machine
also swaps bytes, the "swab" option can be given to dd; depends on
where you want to later read those tapes and how lazy you are.

Can someone with more whit/stamina figure out the correct dd options? It's
late and I'm tired :-{}    [BTW: that was a yawn]

Personally, I use multiple rdumps on the same tape for backups here
and cpio for incrementals.

-- 
"I'm trying             Joe Angelo -- Senior Systems Engineer/Systems Manager
 to think               at Teknekron Software Systems, Palo Alto 415-325-1025
 but nothing
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