Problems writing more than 100Mb per DSS2 tape with TLZ9L

From: <tma_at_nettest.dk>
Date: Tue, 15 Sep 1998 10:56:44 +0100

Hi' everybody,

We use NSR 4.2B and a TLZ9L DAT autoloader from Digital as our backup
system for our file server, but we have the extremely annoying problem
that we very often get as little as 100Mb on a 4/8Gb DSS2 tape.

We have tried a number of things (like prewriting 4Gb of data to the
tape before use; running "mt ret" before recycling...), but nothing
seems to help.

Note the actual ammount of data on a tape varies alot: a little as
448kb(!!!) and as much as 4.1Gb (just once); also the same tape can
vary a great deal (400Mb one time and 1.2Gb the next time round)...

NSR writes the following messages during a backup (which all look all
right to me):

 9/13/98 23:00:01 nsrd: savegroup info: starting Backup Master (with 1 client)
 9/13/98 23:00:22 nsrd: modi:/export/local/alpha3.2 saving to pool 'TMN'
(Backup.021)
 9/13/98 23:06:04 nsrd: media warning: /dev/nrmt1h writing: I/O error, at file
48 record 649
 9/13/98 23:06:04 nsrd: media notice: 4mm 8GB tape Backup.021 on /dev/nrmt1h
is full
 9/13/98 23:06:04 nsrd: media notice: 4mm 8GB tape Backup.021 used 228 MB of
8000 MB capacity
 9/13/98 23:06:24 nsrd: media info: suggest relabeling Backup.022 for writing
to pool 'TMN'

We never see any UERF messages that can be related to this!

We have the feeling that we can write more to the tapes during
incremental backups than during full backups, but we have no hard
numbers to back this feeling...

All this make us think, we have a hardware setup problem... But what
is the problem exactly? Note that the autoloader is on a separate SCSI
bus.

Anybody out there with the same type of problem?

The hardware configuration:

  AlphaServer 1000A 5/400 with
  - 512Mb memory
  - approx. 30Gb diskspace on SCSI buses
  - TLZ9L-DB on a separate SCSI bus.

The (relevant?) software configuration:

  Digital UNIX V3.2G (Rev. 62)
  NetWorker 4.2B for Digital UNIX (BRXSOAKIT422)


/tonny
Received on Tue Sep 15 1998 - 09:05:29 NZST

This archive was generated by hypermail 2.4.0 : Wed Nov 08 2023 - 11:53:38 NZDT