HP BB118BV - StorageWorks Data Protector Express Package, User Manual, Page: 182 / 365

164 Data Protector Express User's Guide and Technical Reference
Organizing machines into workgroups
One strategy for speeding up jobs is to organize machines into workgroups. A workgroup is merely a
folder that contains one or more machines. Once included in a workgroup, files and data on these
machines can be selected together simultaneously in backup job selection list.
If your Data Protector Express management domain includes many machines on a large network with
media servers scattered across subnets, you can speed up jobs by grouping machines on one subnet
together in a workgroup and pointing jobs related to these machines to devices also located on the same
subnet. Since transferring data across a network from one subnet to another takes longer than data
transferred within a single subnet, these jobs will be faster. To set up a workgroup, follow these steps:
To set up a workgroup
1. From the
Administration
desk bar, select
Catalog
.
2. Locate the
Network
in the hierarchical tree view.
3. In the main object detail area of the screen, right-click and select the
New
command.
4. Enter a name for the workgroup and click
OK
.
The new workgroup will be listed under Network along with any machines in the Data Protector
Express management domain.
5. One by one, select each machine that you want to include in the workgroup.
6. Right-click the machine and select the
Move
command.
7. Select a destination under the Network and click OK .
The next time you set up a backup job (or other job), the workgroup you created will be available on the
Selection page of the job.
What Slows Down Tape Drives?
Tape drives work most efficiently when they are “streaming,” that is, when the tape itself is constantly
moving forward and a steady flow of data is being written to the tape as it passes the write head. In
general, tape drives will “stream” if there is a constant flow of data available to write to the tape.
Whenever there is an interruption in the data and the drive must wait for the data, the “stream” breaks off
and the tape stops. Additionally, after the tape stops, the drive must reposition the write head and regain
the velocity of the tape. To do so, the drive will rewind the tape prior to where it stopped writing and then
restart the tape forward again. This can be a time-consuming process, especially if it occurs repeatedly.
For this reason, it is important to keep data constantly flowing to the tape drive. The performance of your
job will be maximized when the tape drive constantly has data available to it.
Maintaining the flow of data
There are several steps you can take to make sure that data is constantly available to the backup device.
Local buses compared to network connections: In general, data is transmitted more efficiently over a local
bus than over a network connection. Thus, for example, performance increases if the backup device is
connected to the file or application server rather than to a different machine on the network, although
either arrangement is possible.
Note that the catalog need not be placed on the same machine as the backup device. The location of the
catalog does not affect the rate of data transmission. (Other job tasks, such as building backup selection