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

tablespace, a segment can include extents from more than one file; that is, the
segment can span datafiles. However, each extent can contain data from only one
datafile. When a new extent is allocated for a segment, Oracle tries to spread (or
stripe) extents among all datafiles in the tablespace at that time. When you run
out of free data blocks in a tablespace, you can add additional datafiles. Here is a
pictorial representation of logical objects and physical storage.
Figure 13-2
Logical objects on storage
Tablespace
Database
Segment
Extent
Oracle data block
Physical data file
Logical Physical
Physical data file
Oracle has several types of segments. Depending on the type, the usage pattern
of the data within the segment varies. For Storage Tiering relocation, it is
important to know what kind of segments is suitable for relocation. Here is a list
of segment types.
■ Data segments: contain data blocks where table rows are stored. Data
segments/extents are prime candidates for relocation to a secondary storage
tier. The old extents contain rows inserted earlier than new extents. Segment
and extent properties are available by querying dictionary table dba_segments
and dba_extents.
Understanding storage tiering with SmartTier
How SmartTier for Oracle works
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