Reorganization of the tape cartridges, 4 reorganization of the tape cartridges – FUJITSU CentricStor V3.1D User Manual

Page 37

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U41117-J-Z125-7-76

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CentricStor - Virtual Tape Library

Administering the tape cartridges

2.5.4

Reorganization of the tape cartridges

When a logical volume is released by the host’s volume management facility (e.g. MAREN
in BS2000/OSD), it is flagged accordingly in the CentricStor data maintenance facility which
contains the metadata for each volume. This process, combined with updates (see the
section

section “Creating a directory” on page 36

), will cause the areas containing invalid

data on the real tape cartridges to increase more and more over time (stacked volume with
gaps). If the number of scratch tapes for a CentricStor system falls below a configurable
lower limit, the PLM automatically performs a reorganization by using the VLM to load any
logical volumes still valid into the RAID system and then, so to speak, moving them
piecemeal onto scratch tapes.

Figure 12: Example of a reorganization

Read tape:

Tape cartridge that still contains valid data but has no free space for write
operations

Scratch tape: Tape cartridge that only contains invalid data and has been released for

rewriting

Write tape:

Tape cartridge that still contains space for write operations

LV0000

LV0001

LV0002

LV0003 LV0004 LV0005

LV0006 LV0007 LV0008

LV0011

LV0009

LV0010

PV0000

PV0001

PV0002

PV0000

PV0001

PV0002

VLM

CentricStor

:

:

LV0037

PV0007

PV0008

:

:

LV0037

PV0007

PV0008

LV0000

LV0001

LV0002

LV0003 LV0004 LV0005

LV0006 LV0007 LV0008

LV0011

LV0009

LV0010

LV0001

LV0002

LV0003

LV0006 LV0007

LV0011

LV0009

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ta

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:

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PLM

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