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Has the drive been moved recently? Have any cables been disconnected and reconnected? Has the environment
changed—unusually hot, cold, damp or dry? Has there been dust or dirt near the drive. Have reasonable precautions
against static been taken?
The problem could lie with the drive:
1.
Check the cables and connectors.
2.
Clean the tape heads with the cleaning cartridge.
3.
If the problem persists, check the environmental conditions against the specified limits, see Table 8 on page 39. Perhaps
move the drive to a more suitable site.
Has a new operating system been installed in the host computer? Has new backup software been installed?
The problem could lie with the host or the software. Consult the computer's operating manuals, the software manual, or
seek help from a service engineer.
Optimizing performance
Various factors can affect tape drive performance, particularly in a network environment. In nearly all cases when performance
is not as expected, it is the data rates of the disk subsystem that cause the bottleneck.
If your tape drive is not performing as well as expected—for example, if backup windows are longer than expected—please
consider the following points before contacting Customer Support.
Is the tape drive on a dedicated SCSI bus?
We recommend that the tape drive is the only device on the SCSI bus. If it is not, ensure that other devices are LVDS compliant.
If they are single-ended, the bus will switch to single–ended mode with a lower transfer speed. There will also be restrictions
on cable length.
Can your system deliver the required performance?
• The LTO–4 tape drive can write uncompressed data at up to 80 MB/s (288 GB/hour).
• The LTO–3 tape drive can write uncompressed data at up to 60 MB/s (216 GB/hour).
• The LTO–2 tape drive can write uncompressed data at up to 24 MB/s (86 GB/hour).
To obtain this performance it is essential that your whole system can deliver this performance. In most cases, the backup
application will provide details of the average time taken at the end of the backup.
Typical areas where bottlenecks can occur are:
• Disk subsystem
A single-spindle disk will not be able to deliver good data throughput at poor compression ratios. Best practice to ensure
good throughput is to utilize multiple disk spindles or data sources.
A single-spindle disk may be sufficient for an LTO-2 tape drive, depending on your data's compressibility. Best practice
to ensure good throughput is to utilize multiple disk spindles or data sources.
• System architecture
Be aware of the architecture of your data protection environment.
The aggregation of multiple client sources over a network provides a good way of delivering good performance, but
anything less than Gigabit Ethernet will limit performance for LTO tape drives.
Some enterprise class backup applications can be made to interleave data from multiple sources, such as clients or disks,
to keep the tape drive working at optimum performance.
• Tape media type
The data cartridge should match the specification of the tape drive. A lower specification will have a lower transfer speed
(see "Data cartridges" on page 35). Use:
• Ultrium 1.6 TB R/W or Ultrium 1.6 TB WORM cartridges with LTO–4 tape drives
• Ultrium 800 GB R/W or Ultrium 800 GB WORM cartridges with LTO–3 tape drives
• Ultrium 400 GB R/W cartridges with LTO–2 tape drives
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Troubleshooting
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