FUJITSU CentricStor V3.1D - Manual (Page 49)

U41117-J-Z125-7-76 49
CentricStor - Virtual Tape Library Optional system functions
In BS2000/OSD (“HOST” attribute), compression is controlled on the basis of the tape type:
– TAPE-C3: compression off
– TAPE-C4: compression on
In UNIX, the compression setting can be selected by the device nodes.
The compression setting can be passed in ESCON or SCSI command to the tape
emulation, and the compressed data is stored block-by-block on the logical volume (the
VLM and PLM do not have any information about this).
If the data is already compressed on the host, e.g. if backup data is supplied in
compressed format by a NetWorker client, then compression should be switched off
for this logical volume on the ICP, so that the load on the CPU of the ICP can be kept
to a minimum.
2.9.2 Multiple library support
One of the important characteristics of CentricStor is the parallel connection of multiple real
robot archives of different types.
Figure 16: Example of multiple library support
The number of robot archives that can be operated in parallel is theoretically unlimited.
However, since at least one physical volume group is required per library, it is only possible
to support as many libraries as there are corresponding volume groups.
i
Fujitsu robot IBM Cashion StorageTek ADIC
CentricStor
Hosts
Robot archive
Host1 Host2