Optimizing Performance; Problems With Cartridges - Lenovo ThinkServe LTO User Manual

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 Technical Support.
• Disk subsystem
A single spindle disk will not be able to deliver good data throughput for
an LTO tape drive at any compression ratio. To maximize the capability
of these tape drives, utilize aggregated disk sources (RAID) with multiple
disk spindles.
• System architecture
Be aware of the architecture of your data protection environment; multiple
clients backed up over a network may mean you are unable to take ad-
vantage of the LTO tape drive because the Ethernet infrastructure con-
necting such systems may limit performance.
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 54).
• Data and file types
The type of data being backed up or restored can affect performance.
Typically, small files incur greater overhead in processing and access
than large files. Equally, data that is not compressible will always limit
the speed at which the drive can write/read data. You will achieve no
more than native rates with uncompressible data.
Examples of files that compress well are plain text files, spreadsheets;
those that compress poorly are those that are either compressed as part
of their format (such as, JPEG photographic files) or stored as com-
pressed (such as, .ZIP files or .gz/.Z files on Unix platforms).

Problems with cartridges

If you experience any problems using LTO branded cartridges, check:
• The cartridge case is intact and that it contains no splits, cracks or
damage.
November 2012
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