burzio@mmlai.UUCP (Tony Burzio) (04/07/89)
After a long time reading through the man pages about
find, cpio, and tcio, I came to the conclusion that the backup
script in /etc makes poor use of a 9144A cartridge tape drive.
The following replacement will 1) only backup up the local hfs
file system 2) turns off verification (HP told me it was OK) and
3) lets the tape drive stream using the small (8) buffer size in
conjunction with the read-while-write tape head capability. Give
this a try, because it speeds the backup -archive process quite a
bit.
{ find $backupdirs $aflag -fstype hfs -hidden -print |
cpio -ocxa |
tcio -oVS 8 $dest
} 2>>$backuplog # log stderr only.
*********************************************************************
Tony Burzio * A hacking we will go....
Martin Marietta Labs *
mmlai!burzio@uunet.uu.net *
*********************************************************************rjn@hpfcdc.HP.COM (Bob Niland) (04/10/89)
re: "tcio -oVS 8 $dest"
2. "V" (turn off verification). Go for it. This option is generally used
only on older "Linus" tape drives in the 7908/11/12/14P/R/TD/ST-series
discs. "Linus" did not have read-while-write, so the extra Verify pass
was useful to ensure that no unrecoverable errors were written.
The current tape drives in the 35401A, 7914CT, 7942/46A, 9144A and 9145A
products have both write and read gaps in the head, and verify on the
fly. The extra verify pass on completion of write is as likely to induce
an error (due to tape wear) as it is to find one; very unlikely in either
case. If you are very cautious, and want to improve the already high odds
of recovery backup data, perform a 'mediainit -r' on the tape before
writing to it. This will pre-spare any marginal blocks.
This second (newer) group of drives also support "immediate report". The
"Linus" drives do not. Immediate report (enabled by the 'tcio' filter)
allows the drive to acknowledge write-complete upon receipt of the data
into its buffer. It doesn't wait until the data is copied to the tape,
which brings us to...
3. "S 8" (use 8K buffer). Use less than the default 64K buffer size only
if you have:
* a Model 330 or faster computer;
* a fast disk (<30 mS seek, >700 K transfer rate);
* the disk is connected via SCSI or high-speed HP-IB;
* the tape supports "immediate report", and;
* the 'tcio' filter is used.
Most Series 300 systems meet this criteria. If you have a 320, try it
both ways and compare. I wouldn't recommend "S 8" for a 310. Even if
you have a faster system, if you routinely backup a "live" file system
while users are logged in and are keeping the system busy, watch (and
listen to) the tape drive. If you can't keep it streaming most of the
time, don't use "S 8".
On a slower/busy system, find/cpio will not be able to gather bits from
the file system fast enough to keep the tape streaming. The excess
repositioning on a slow/busy system (or on a "Linus" drive) will result
in reduced net backup performance, and may thrash the poor tape drive to
death over time.
Regards, Hewlett-Packard
Bob Niland rjn%hpfcrjn@hplabs.HP.COM 3404 East Harmony Road
[hplabs|hpu...!hpfcse]!rjn Ft Collins CO 80525-9599maddog@cbnews.ATT.COM (john.j.tupper) (04/12/89)
In article <5570149@hpfcdc.HP.COM> rjn@hpfcdc.HP.COM (Bob Niland) writes: > Immediate report (enabled by the 'tcio' filter) Speaking of which, is there any reasonable way of enabling immediate report mode without using tcio? Seems like there should be an ioctl call to do it, but there isnt. . . ------------------------------------------------------------------------ sdfj sldkfslkdjf My real signature is illegible too