IBM E16RMLL-I - Tivoli Storage Manager, Implementation Manual, Page: 218 / 828

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IBM Tivoli Storage Manager Implementation Guide
5.1 Database
The database is a critical Tivoli Storage Manager component. It must be
configured for good availability performance.
5.1.1 Database design considerations
Before you start, there are a few important differences to consider, depending on
which platform you will be using.
Tivoli Storage Manager has a single database made up of one or more
volumes
.
A database volume is a physical file located on one of the server’s file systems.
In other words, the database is a logical entity made up of physical files.
Database volume numbers, sizes, and locations affect database performance.
The following points should be considered:
򐂰
All database volumes must reside on random access media, that is, disk
drives.
򐂰 If there is more than one database volume, more than one process can
access the database simultaneously.
򐂰
If there is more than one database volume, the data is distributed across all
available volumes and writes to the database volumes are performed in a
round-robin
fashion. Suppose the database has three volumes, vol01, vol02,
and vol03. A sequence of four writes would go 1 to vol01, 2 to vol02, 3 to
vol03, and 4 to vol01. Writing in a round-robin fashion distributes the load and
makes the most of available resources.
򐂰 Create database volumes the same size if possible.
򐂰
Database segments are 4 MB in size, so a volume must be a multiple of
4 MB. One recommendation is to make your database volume sizes a
multiple of the power of 2, that is, 128 MB, 256 MB, 512 MB, 1024 MB,
2048 MB, and so on.
򐂰 Tivoli Storage Manager requires 1 MB of space (known as the
restart area
) at
the start of the volume. Take this overhead into account when calculating disk
usage.
Platform-specific information: Some minor changes are required in
UNIX/Linux and Windows because of the different file space naming
conventions of those platforms. The examples in this section are from
Windows and AIX systems. Use the correct directory separator for your
platform when entering file and path names. For other platforms, see the IBM
Tivoli Storage Manager Administrator's Reference for that server.