HP StoreEver Ultrium Tape Drives - Manual (Page 23)

5. You can also use the data to see what compression ratios are being achieved.
This is not something that can normally be changed, but it is useful to know how well the user
data is actually compressing. This information is not usually available, yet has a significant impact
on how much data can be written to a tape and the potential host data rates that can be
accommodated. Note that the write and read compression ratios can be different if different data
sets are used, such as when a full volume backup is followed by a partial read/verify.
Conducting a utilization assessment for drives
Once you measure how much your tape drives are used, you can make improvements.
1. Determine the sample period over which you want to measure utilization.
Different jobs for backups, restores, archival or other needs will show different utilization behavior.
Select a representative time period, such as a week, which covers a typical cycle, such as a full
backup followed by a week of incremental backups.
2. To view drive utilization data from the TapeAssure tab, select Drives > Utilization from the
navigation pane.
Utilization appears under the column: Utilization (%) (in sample time).
3. To select the sample time, click on the Actions pull-down list.
4. Click OK and the Utilization data will be refreshed based on the new sample period. You can
also see the following data about sampling:
• The Sample Size column displays the number of unique tickets pulled during the sample
period and the last sample time – the time of the last ticket. Note that a unique ticket is one
with a unique tape load count.
In this example, the sample time has been set to (a rolling window of) 24 hours and only the last
two drives listed have been used during that time – but these have been used quite a bit. The
first of these has been used 66.1%, which is approximately 16 hours over the last 24.
5. Depending on the utilization data, you should consider the following:
• If drive utilization is generally lower than expected, the there is an opportunity to make better
use of the drives. That may be achievable through, for example, different scheduling of
backups.
• If drive utilization is uneven, you can spread the load across all your drives, which is preferable
for longer drive life.
• If drive utilization is very high, that is also good to know. It shows that good use is being
made of the equipment and it is also a potential warning that a capacity increase may be
needed – along with the evidence needed to support that request.
User guide 23