Installation guide

56
Configuring Your IP4700 Device for Use with Backup Software
Monitoring your Backup Performance
jukebox has changed. Otherwise, the backup software must put each
tape into a drive in order to identify a tape.
Tape Handling
Do not affix labels to any part of the tape cartridge other than the bar
code. Such labels can fall off inside the drive and damage it.
“Swallowed leaders” can result when a loop on the end of the leader
in the DLT tape cartridge has been damaged or worn. Catastrophic
damage can also occur to a DLT tape cartridge if it is dropped from a
height of three feet or more. Loading such a tape into a DLT drive will
result in a swallowed leader, and the drive will need servicing. You
can test a dropped tape by loading and unloading ten times in a
standalone DLT tape drive.
Monitoring your Backup Performance
Several factors affect backup performance. When your backup server
was installed, the System Engineer verified the backup throughput;
however, your environment may have changed over time, or certain
factors may not have been considered when the System Engineer
installed the backup server. This section describes some of the factors
that affect backup performance. For more specific information about
these factors, refer to your backup software documentation.
DLT7000 Tape Drive
Performance
The most important hardware component of the backup system is the
tape device. The drive itself has a native (uncompressed) throughput
of 5 Mbytes per second. Depending on the exact data being recorded,
the drive throughput may increase to 10 Mbytes per second or
slightly more. However, when two of these drives are active on the
same SCSI bus, each will attain a maximum of 8.5 Mbytes per second.
The NetWorker Administrator provides an accurate representation of
each tape drive’s throughput while backing up. If you notice a drive
running significantly slower than 5 Mbytes per second, investigate.
Performance that is less than 5 Mbytes per second on a tape drive is
acceptable if one of the following conditions exists:
• Backup had proceeded fine earlier with good performance on the
drive, but now there are only one or two sessions from slow client
systems.
• The tape drive has encountered a bad spot on the tape, and its
throughput is momentarily reduced by write retries. Wait a
minute to see if the slow throughput continues.