Information Technology Reference
In-Depth Information
Table 14.3
Classes of SVM Volumes
Volume
Description
RAID 0
Used directly or as a building block for mirror and transactional vol-
umes (the three types of RAID 0 volumes are stripes, concatenations,
and concatenated stripes)
RAID 1
Used to mirror data between RAID 0 volumes to provide redundancy
RAID 5
Used to replicate data with parity, allowing regeneration of data
Transactional
Used for UFS file system logging
Soft Partition
Used to divide a disk slice into one or more smaller slices.
SVM allows volumes to be dynamically expanded by adding additional slices.
Then a UFS file system on that volume can be expanded.
Soft Partitions
As disks become larger, sometimes it might be necessary to subdivide a phys-
ical disk into more than eight slices (which is the current limit). With SVM,
a disk slice can be subdivided into as many
soft partitions
as needed. A soft par-
tition can be accessed like any disk slice and can be included in a SVM vol-
ume. Although a soft partition appears as a contiguous portion of disk, it
actually consists of a set of
extents
that could be located in various areas of the
disk.
State Database and Replicas
The
State Database
is used to store information about the SVM configura-
tion. Because this information is critical, copies of the State Database,
referred to as
State Database Replicas,
are maintained as backups and ensure
that the state information is always accurate and accessible. SVM updates the
State Database and replicas whenever changes are made to the disk configu-
ration.
The State Database and its replicas can be stored on either disk slices dedi-
cated for database use or on slices that are part of volumes. When a slice that
contains the database or a replica is added to a volume, SVM recognizes this
configuration and skips over the database or replica. The replica is still acces-
sible and usable. The database and one or more replicas can be stored on the
same slice, however it would be advisable to distribute the replicas across
several slices to safe guard against the failure of a single slice.
