Veritas Storage Foundation™ for Oracle 5.0.1 Administrator's Guide

individual volumes that make up the LBFS and volume set be of same size and
same access properties. Setting up the file system in this way provides the same
benefit as striping your volumes. Use the dbdst_makelbfs command to create an
LBFS file system. Note that you cannot convert an existing file system to an LBFS
file system.
Extent balancing file system
You can define allocation policies with a balance allocation order and "chunk"
size to files or a file system, known as extent balancing. The chunk size is the
maximum size of any extent that files or a file system with this assigned policy
can have. The chunk size can only be specified for allocation policies with a balance
allocation order.
An extent balancing policy specifies the balance allocation order and a non-zero
chunk size. The balance allocation order distributes allocations randomly across
the volumes specified in the policy and limits each allocation to a maximum size
equal to the specified chunk size.
Extent balancing extends the behavior of policy enforcement by rebalancing
extent allocations such that each volume in the policy is as equally used as possible.
Policy enforcement handles the following cases:
■ New volumes are added to the policy, and the extents associated with a file
need rebalancing across all volumes, including the new ones.
■ 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.
Using Database Dynamic Storage Tiering
Extent balancing in a database environment
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