Fujitsu Siemens Computers CentricStor V3.1D, User Manual

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U41117-J-Z125-7-76
Reorganization Selected system administrator activities
4.4.5 Own physical volumes for reorganization backup
The PLM distinguishes between backup requests from the host and backup requests which
are caused by a reorganization. As long as the number of
scratch tapes
is above the
hard
minimum , the PLM attempts to use a physical volume exclusively for the request type invol-
ved. The reason for this is as follows: the logical volumes affected by the same request type
are more similar to each other in terms of the retention period of their data than to those
affected by the other request type. Consequently, in the event of separate backup according
to the request type, either a very high or very low occupancy level of the physical volumes
is more probable than a medium occupancy level, and the tape backup is therefore more
efficient.
However, as a result the number of mount requests during reorganization increases. If the
separation of physical volumes for host backup requests and for reorganization conse-
quently proves to be disadvantageous, the service staff can suppress this by means of a
configuration switch.
4.4.6 Starting the reorganization of a physical volume
The form and detailed information are provided in the section “Physical Volume Operations
» Reorganize Physical Volumes” on page 257 .
The following information must be specified:
– the VSN of the physical volume
– the name of the physical volume group
If another physical volume is currently being reorganized either explicitly or automatically,
this process is aborted and reorganization of the physical volume currently specified in
GXCC is initiated.