The original question is at the end, thanks to alan_at_nabeth.cxo.dec.com who told
me about tape drives that forget they should compress, but thought a reboot
should fix it (unfortunately this was not the case with us), and Dr. Tom Blinn, but
the answer came finally from CSC. They were unwilling to call it a bug but what
happens is that the tape forgets how to compress and has to be reminded, and the
only way to do this is to do a tar to the tape device before each backup that uses
vdump. According to CSC setting the switches on the device, using the 0h device or
the -C option have no effect.
Linda
--- Begin Forwarded Message ---
Date: Wed, 29 Oct 1997 15:44:53 +0000 (GMT)
From: Linda Richardson <L.Richardson_at_canterbury.ac.uk>
Subject: Compression onf TLZ07???
Sender: alpha-osf-managers-relay_at_sws1.ctd.ornl.gov
To: alpha-osf-managers_at_ornl.gov
Reply-To: Linda Richardson <L.Richardson_at_canterbury.ac.uk>
Message-ID: <SIMEON.9710291553.G_at_linda-s-pc.canterbury.ac.uk>
Hello,
I've looked through the archives and although there is one summary that sounds
remarkably like our problem, it doesn't give enough information for us to solve it.
The scenario:
We have been backing up around 3.8G- 4G of data to a TLZ07 using
/sbin/vdump -0 -N -u (full, norewind,update files)
As I understand it this uses the default tape device which is rmt0h and should
therefore compress. We noticed the backup had suddenly started to take longer,
which may have been due to the bus reset problems we were having. Our backups then
started to fail with 'out of space' errors in the log files. Digital came and
upgraded the firmware on the disks, no change, they then changed the controller, no
change. They have now changed the tape drive (several times) but to no avail.
A summary in the archives from 31 Oct 1996 seems to be the same problem and gives
the solution as turning off compression switch, but according to my hardware book
there is no switch, one either uses the rmt0h device or -C. Also why did this
suddenly start to happen??
Any ideas, anyone? This has been going on for 2 weeks now, with Digital people
seeming to be grasping at straws, and if we take the system down any more then our
users will be out for blood!!
TIA
Linda
----------------------
Linda Richardson, Systems and Networking Manager,
Canterbury Christ Church College,
North Holmes Road, Canterbury Kent CT1 1QU
email: linda_at_cant.ac.uk
--- End Forwarded Message ---
----------------------
Linda Richardson, Systems and Networking Manager,
Canterbury Christ Church College,
North Holmes Road, Canterbury Kent CT1 1QU
email: linda_at_cant.ac.uk
Received on Fri Nov 07 1997 - 13:39:41 NZDT