The following options are available only if the TurboSTORE/iX II product
is purchased.
In addition to all of the STORE options, the following additional
options are available with TurboSTORE/iX II. For more information on
purchasing TurboSTORE/iX II, contact your Hewlett-Packard sales
representative.
Compressing Data (COMPRESS) |
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With TurboSTORE/iX II (and TurboSTORE/iX 7x24 True-Online Backup),
backup performance can be improved through the use of host data
compression. By specifying the COMPRESS parameter, the host system
filters the data through a compression algorithm prior to writing it to
the backup device. This operation has two effects:
The device's throughput is increased by transferring more data than the
device's maximum sustained rate. The increase is dependent upon
available CPU resources.
Fewer media changes are required by putting more data on each piece of media.
Two levels of compression are supported by the COMPRESS parameter:
HIGH and LOW.
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 | NOTE:
No matter whether you specify HIGH or LOW, the actual level of
data compression is dependent upon the type of data being compressed.
For example, program files will not compress as much as data files. |
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You must determine which of the compression algorithms best suits your needs.
In some cases the low-compression algorithm may perform almost as well as,
or better than, the high-compression algorithm.
It is advisable to try both algorithms on your data in order to evaluate
which algorithm best suits your needs. Some of the factors to consider
are:
Amount of CPU time required.
Amount of media required.
Be advised that when performing backups with the high-compression
algorithm, the backup can consume much or most of the processing
capabilities of the machine. The exact amount of system resources
consumed depends on your system speed and multi-processor configuration.
Using the low-compression algorithm demands less system resources, so it
is easier for other activity to coexist with the backup.
Use the high-compression algorithm if backup time is dedicated or if the
difference in the amount of media used for backup is substantial enough
to warrant the complete consumption of the machine.
When compressed format files are restored, RESTORE automatically
recognizes the compressed format and restores the files properly.
To compress data when storing files to backup, use the FILE command,
then use the COMPRESS parameter in your STORE command. For
example:
:STORE @.OPERATOR.SYS;*T;COMPRESS=HIGH
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 | WARNING! If you are using a backup device that performs hardware data
compression, COMPRESS=HIGH should NOT be used. Performing
compression twice is redundant, and in some cases can lead to slower
backup performance. The best throughput results occurs when using no
compression or COMPRESS=LOW with hardware compressing devices. |
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To compress data when storing files to magneto-optical disks, use the
MOSET and COMPRESS parameters in your STORE command. For
example:
:STORE @.@.@;;MOSET=(101);NAME=DAILY.D24SEPT.TIGER;COMPRESS=HIGH
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Storing to Magneto-Optical Devices (MOSET and NAME) |
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TurboSTORE/iX II allows you to store backup data to magneto-optical (MO)
devices. This is done by using the MOSET option to specify which
MO devices should be used for the backup.
The NAME option is used to associate a logical name with the backup.
This name is used during the restore process to identify which backup
should be used.
These options are discussed in detail in Chapter 3, "Preparing Storage
Devices". Please refer to that chapter for more detailed information on
using the MOSET and NAME options.
