Slow Backups - Certance LTO 1 User Manual

Troubleshooting Guide

Slow Backups

There are many factors that can make backups appear to be "slow." To achieve the highest possible
transfer rate, the LTO-1 or LTO-2 tape drive MUST be attached to a Low Voltage Differential ( LVD )
SCSI controller capable of a minimum of 80 MB/s and MUST not share the same SCSI bus as
another active SCSI device such as hard drives.
1. Is the tape drive attached to an LVD SCSI controller? This can be determined by viewing the
boot process of the system and looking to see what controller the tape drive is attached to.
There may be boot log files that can be examined to determine what SCSI controller the tape
drive is attached to.
2. If the tape drive is not attached to an LVD SCSI controller, attach the tape drive to a LVD SCSI
controller to achieve best possible hardware performance for best possible transfer rate.
3. If the tape drive is attached to an LVD SCSI controller, see whether the tape drive is the only
device on the SCSI cable? This can be determined by viewing Windows Device Manager,
viewing Unix/Linux logs, or by viewing SCSI controller during system boot up.
If other SCSI devices are attached to the SCSI controller and are active during the time when
4.
a backup is performed to the tape drive, have the tape drive as the only device on the SCSI
cable to achieve the best possible backup performance.
The method of performing the backups can also be a factor in "slow" backups. Data sent to the tape
drive over a network connection and delays in data transfer over a network connection can cause
backups to slow down.
Perform write/read test with diagnostic software. This ensures a test of the connection
1.
between the tape drive and SCSI controller and removes the network data transfer and the
backup software from the diagnosis. The write/read test WILL OVERWRITE DATA ON THE
TAPE.
2. When the test finishes, determine the megabyte per second data transfer. The resulting calcu-
lation shows the tape drive performing at an acceptable rate.
3. If you believe that the write/read transfer is slow even after using the diagnostic software
write/read test, use the Certance Tape Diagnostic software to perform a trace buffer retrieval.
Send the file to Technical Support, so that the state of the SCSI bus can be determined.
4. If the diagnostic write/read test transfer rate is acceptable, but backups still seem to be
"slow," it may be attributed to the number of files and the average file size that are to be
backed up. These factors can have a significant effect on the backup performance. Backups
where the average file size is less than 200k bytes are slower than backups where the aver-
age file size is greater than 200k bytes. Obtain backup log files to determine number of files
and average file size.
Manually Removing a Cartridge
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