Veritas Storage Foundation 5.1 SP1: Storage and Availability Management for Oracle (5900-1504, April 2011)

■ Volumes are removed from the volume set or from the policy, and the extents
for a file residing on a removed volume need to be moved to other volumes in
the policy.
■ An extent balancing policy is assigned to a file and its extents have to be
reorganized to meet the chunk size requirements defined in the policy.
The extent balancing policy is intended for balancing data extents belonging to
files across volumes defined in the policy. However, there is no restriction imposed
in assigning extent balancing policy for metadata.
Note: If the fixed extent size is less than the chunk size, then the extent size will
be limited to the largest multiple of the fixed extent size that is less than the chunk
size. If the fixed extent size is greater than the chunk size, then the extent size
will be the fixed extent size.
Creating an extent balanced file system
Any multi-volume file system (MVFS) can become an extent balanced file system,
if the storage tier has a chunk size associated with the class. The dbdst_admin
command permits the user to define a chunk size for the class.
For example, the following dbdst_admin commands define chunk sizes for the
gold and silver storage classes:
$ /opt/VRTS/bin/dbdst_admin -S $ORACLE_SID \
-o definechunk=gold:256K
$ /opt/VRTS/bin/dbdst_admin -S $ORACLE_SID \
-o definechunk=silver:128K
For example:
$ /opt/VRTS/bin/dbdst_admin -S $ORACLE_SID \
-o definechunk=TIER1:256K
The above commands make storage class gold as extent balanced.
Once the chunksize is defined for a storage tier, we can classify any MVFS into
this storage tier.
For example, assume that /oradata is the filesystem created on volume-set
/dev/vx/dsk/oradg/ora_vset, and contains database datafiles. Let us further assume
that datafile names end with extension *.dbf. To define storage class in this MVFS,
the following dbdst_classify command is used:
Configuring and administering SmartTier
Extent balancing in a database environment
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