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U41117-J-Z125-7-76 77
Selected system administrator activities Reorganization
Only physical volumes in read status on which the relative proportion of valid data is less
than the percentage value configured in the Fill Grade parameter are taken into account. If
a physical volume is in write status and the percentage value for its valid data drops below
the Fill Grade value, it is placed in read status and is therefore a candidate for reorganization.
The costs are estimated according to the following formula:
( N * estimate1 ) + ( M / estimate2 )
where
N Number of valid logical volumes on the physical volume
estimate1 Estimated overhead, in seconds, for each logical volume which is to be writ-
ten (configuration parameter Write Overhead)
M Sum, in MiB, of the data contained on the valid logical volumes
estimate2 Estimated write performance in MiB/sec (configuration parameter Write
Throughput)
When the two estimated values are configured, it must be borne in mind that these do not
depend solely on the hardware characteristics of the tape drives, but also to a large degree
on the relative size of the valid logical volumes. For example, large logical volumes have
fairly certainly been displaced from the TVC and would have to be read in first, which practi-
cally doubles the time required and halves the write performance.
Example
pos PV TL PVG state next-bl LVs - val cap/GB valid/GB valid %
:
15 CSJ016 JAGUAR JAG001 _r__ 2518971 1156 583 279.397 0.000 0
16 CSJ017 JAGUAR JAG001 _r__ 1109297 16 1 279.397 15.795 5
:
The default values (Write Overhead = 3, Write Throughput = 5) result in the following costs:
CSJ016 is therefore selected.
Example with Write Overhead = 3 and Write Throughput = 20:
CSJ017 is therefore selected.
PV Number of valid LVs Valid data volume (MiB) Estimated costs
CSJ016 583 0 1749
CSJ017 1 16155 3234
PV Number of valid LVs Valid data volume (MiB) Estimated costs
CSJ016 583 0 1749
CSJ017 1 16155 810