IBM System Storage DS3000, Руководство по программированию

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Parameter Description
T10PI
The setting to specify that an subsystem, and the logical
drives within the subsystem, has T10 PI (Protection
Information) protection to make sure that the data
maintains its integrity. When you use this parameter,
only protected drives can be used for the subsystem.
These settings are valid:
v
none — The subsystem does not have T10 PI
(Protection Information) protection.
v enabled — The subsystem has T10 PI (Protection
Information) protection. The subsystem supports
protected information and is formatted with protection
information enabled.
Notes
You can use any combination of alphanumeric characters, hyphens, and underscores for the names.
Names can have a maximum of 30 characters.
The owner parameter defines which controller owns the logical drive. The preferred controller ownership
of a logical drive is the controller that currently owns the subsystem.
If you do not specify a capacity using the
capacity
parameter, all of the available capacity in the free
capacity area of the subsystem is used. If you do not specify capacity units,
bytes
is used as the default
value.
Segment Size
The size of a segment determines how many data blocks that the controller writes on a single disk drive
in a logical drive before writing data on the next disk drive. Each data block stores 512 bytes of data. A
data block is the smallest unit of storage. The size of a segment determines how many data blocks that it
contains. For example, an 8-KB segment holds 16 data blocks. A 64-KB segment holds 128 data blocks.
When you enter a value for the segment size, the value is checked against the supported values that are
provided by the controller at run time. If the value that you entered is not valid, the controller returns a
list of valid values. Using a single disk drive for a single request leaves other disk drives available to
simultaneously service other requests.
If the logical drive is in an environment where a single user is transferring large units of data (such as
multimedia), performance is maximized when a single data transfer request is serviced with a single data
stripe. (A data stripe is the segment size that is multiplied by the number of disk drives in the subsystem
that are used for data transfers.) In this case, multiple disk drives are used for the same request, but each
disk drive is accessed only once.
For optimal performance in a multiuser database or file system storage environment, set your segment
size to minimize the number of disk drives that are required to satisfy a data transfer request.
Cache Read Prefetch
Cache read prefetch lets the controller copy additional data blocks into cache while the controller reads
and copies data blocks that are requested by the host from the disk drives into cache. This action
increases the chance that a future request for data can be fulfilled from cache. Cache read prefetch is
important for multimedia applications that use sequential data transfers. The configuration settings for
the storage subsystem that you use determine the number of additional data blocks that the controller
reads into cache. Valid values for the
cacheReadPrefetch
parameter are
TRUE
or
FALSE
. You do not need to
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IBM System Storage DS3000, DS4000, and DS5000: Command Line Interface and Script Commands Programming Guide