Set Logical Drive Mapping - IBM System Storage DS3000 Programming Manual
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Also See for System Storage DS3000:
- Introduction and implementation manual (602 pages) ,
- Installation manual (38 pages) ,
- Owner's manual (18 pages)
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Segment Size
The size of a segment determines how many data blocks that the controller writes on a single drive in a
logical drive before writing data on the next 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 drive for a single request leaves other 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 drives in the subsystem that
are used for data transfers.) In this case, multiple drives are used for the same request, but each 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 drives that are required to satisfy a data transfer request.
Set Logical Drive Mapping
This command defines the logical unit number (LUN) mapping between a logical drive a host or host
group. This command is applicable to logical drives in either an subsystem or disk pools.
Note: You cannot use this command for an Enhanced FlashCopy logical drive that is used in online
logical drive copy.
Syntax
set (logicaldrive ["logicaldriveName"] | logicaldrive <wwID> | accessLogicalDrive)
logicalUnitNumber=LUN
(host="hostName" |
hostGroup=("hostGroupName" | defaultGroup)
Parameters
Parameter
logicaldrive
accessLogicalDrive
logicalUnitNumber
host
Description
The name of the specific logical drive for which you
want to define mapping. Enclose the logical drive name
in double quotation marks (" ") inside of square brackets
([ ]).
The World Wide Identifier (WWID) of the logical drive
for which you are setting properties. You can use the
WWID instead of the logical drive name to identify the
logical drive. Enclose the WWID in angle brackets (< >).
The logical unit number for the access logical drive. The
logical unit number is the only property that you can set
for the access logical drive.
The logical unit number that you want to use to map to
a specific host. This parameter also assigns the host to a
host group.
The name of the host to which the logical drive is
mapped. Enclose the host name in double quotation
marks (" ").
Chapter 3. Script Commands
3-231
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