Silicon Graphics InfiniteStorage 4000 Series, Настройка и обслуживание

Страница: 70 / 276

58 Configuring a Storage Array with Volume Groups
If the volume is for a single user with large I/O requests (such as multimedia),
performance is maximized when a single I/O request can be serviced with a single
data stripe. A data stripe is the segment size multiplied by the number of drives in the
volume group that are used for data storage. In this environment, multiple drives are
used for the same request, but each drive is accessed only once.
The
cacheReadPrefetch
parameter turns on or turns off the ability of the
controller to read additional data blocks into the cache. When you turn on cache read
prefetch, the controller copies additional data blocks into the cache while it is reading
requested data blocks from a drive into the cache. This action increases the chance
that a future request for data can be fulfilled from the cache, which improves the
speed with which data is accessed. The number of additional data blocks that the
controller reads into the cache is determined by the configuration settings for the
storage array that you use. Cache read prefetch is important for applications that use
sequential I/O, such as multimedia applications.
Valid values for the
cacheReadPrefetch
parameter are
TRUE
or
FALSE
. If you
want to turn on cache read prefetch, set the
cacheReadPrefetch
parameter to
TRUE
. If you want to turn off cache read prefetch, set the
cacheReadPrefetch
parameter to
FALSE
.
The following table lists the default values for the segment size and cache read
prefetch settings for different storage array uses.
Table 11 Default Values for Segment Size and Cache Read Prefetch
Use the
securityType
parameter when you have security-capable drives that can
support the Drive Security premium feature. This parameter enables you to specify
the security level when you create the volume group that uses the security-capable
drives. The settings for the
securityType
parameter are the following:
 none
– The volume group and volumes are not secure.
 capable
– The volume group and volumes are capable of having security set,
but security has not been enabled.
 enabled
– The volume group and volumes are security enabled.
After you have finished creating the volume groups and the volumes by using the
autoConfigure storageArray
command, you can further define the
properties of the volumes in a configuration by using the
set volume
command.
Storage Array Use Segment Size (KB) Cache Read Prefetch
File system
128 TRUE
Database
128 TRUE
Multimedia
256 TRUE