Veritas-bu

[Veritas-bu] Backups running slower for no apparent reason?

2004-12-07 22:40:58
Subject: [Veritas-bu] Backups running slower for no apparent reason?
From: StewaBC AT NORTHAMERICA.Stortek DOT com (Stewart, Brian C)
Date: Tue, 7 Dec 2004 22:40:58 -0500
Solaris and LTO. I would recommend setting your;
 - NET_BUFFER_SZ to 512K or 1M
 - SIZE_DATA_BUFFER to 128K or 256K
 - NUMBER_DATA_BUFFER to 64 or 128

This should put a little spring in your tape drive's step. Tuning buffers
aside I would guess your bottle neck is at the client level.
Multi-streaming, multiplexing can have great improvements.

You did not mention if your clients are 10/100 LAN, Gig E LAN or SAN
attached. You did not mention if your drives were direct SCSI, Point to
Point Fibre or on a SAN.

Search your BPTM log for "waited for" messages. This should tell you how log
the tape drive waited for the system or how long the system waited for the
tape drive.

The TAR command is the same as the NetBackup BPKAR command. Well sort of...
NetBackup uses the standard GNU-TAR utility under the covers to write to
tape. The standard TAR utility uses a block size of 10 bytes or 10 K, I
can't remember. This is an unacceptable value for any tape drive besides a
DAT-2 4mm drive. I like to use the command "tar -cvfb <block_size/2>
/dev/rmt/0 ... To specify a larger block size.