Original Question/Problem:
What are the performance considerations for using a high-speed DLT tape
library (TL894) across the network?
Thanks To:
John Warren
Blake Roberts
Raviprasad Venkata
Chan T. Cao
Kenneth Forward
Bryan Bahnmiller
Stanley Horwitz
Erik Persson
I received a motherload of information in a matter of minutes to this
question. The general consensus was to install a second NIC for each of the
machines that will be accessing the DLT tape library so that you will
achieve maximum bandwidth and not adversely affect your existing network.
The second network should be subnetted such that its traffic is isolated,
and the faster the network the better. (FDDI, ATM, Fast Ethernet.)
Some additional goodies that were mentioned:
* Several people preferred Veritas NetBackup instead of Legato. BudTool
(now owned by Legato) is good for traditional dump/restore ufs tasks.
* Negative comments were heard regarding Networker support; Purchasing
direct from Legato seems a good idea given Compaq's message regarding
retirement of NSR; NSR 4.x is not Y2K compliant
* Don't put more than 2 tape drives per SCSI channel. (In our case we are
using 4 drives and will be getting 2 SCSI cards.)
* Benchmarks that were mentioned regarding performance included around 3
hours to backup 100GB using a TL894 (4 parallel drives) across the network;
4-9 MB/sec using DLT7000's in an STK library using Veritas' NetBackup; 4-9
MB/sec over the network using a DLT7000 and BudTool; up to 10MB/sec for a
tape drive directly attached to the machine; up to 9MB/sec with the average
being around 6MB/sec on a TL896 that I believe was directly attached to the
machine being backup up
* Ethernet is not the best medium for backup because of collions and packet
fragmentation. (Perhaps this is why so many people seem to prefer FDDI?)
* Remember to consider CPU performance on both client and server when
performing a backup. A quick and dirty way to speed up backups is SOMETIMES
to tell a client to use standard directives WITH compression so that the
compression gets done on the client CPU rather than on the server or tape
drive.
Received on Mon May 10 1999 - 18:12:02 NZST