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Use this action to set the size of the chunk of data that the controller reads from
each physical drive at a time. To maximize overall performance, choose a
stripe-unit size that is close to the size of the system I/O request.
Attention: After you configure an array and store data on the logical drives, you
cannot change the stripe-unit size without destroying data in the logical drives.
1. In the Enterprise view, click
(controller).
2. Right-click Change stripe-unit size and then click a stripe-unit size. The
following choices are available:
8 KB With this stripe-unit size, an array can have a maximum of 16 physical
drives.
16 KB With this stripe-unit size, an array can have a maximum of 16 physical
drives.
32 KB This setting is available if the controller supports an array with 16
physical drives using a 32 KB stripe-unit size, or the controller contains
no arrays with more than 8 physical drives. Otherwise, this setting is
unavailable.
64 KB This setting is available if the controller supports an array with 16
physical drives using a 64 KB stripe-unit size, or the controller contains
no arrays with more than 8 physical drives. Otherwise, this setting is
unavailable.
More information
v Fine-tuning your system
v Understanding stripe-unit size
v Understanding enabled and disabled read-ahead cache mode
Changing the write-cache mode on a logical drive
Note:
1. This action is supported in bootable-CD mode for ServeRAID SCSI
controllers.
2. This action is supported in interactive mode only for ServeRAID SAS
controllers (8i/8k/8k-l) and the ServeRAID-7t controller.
3. This action is not supported on the integrated RAID controller.
v
Note:
1. (RAID level-x0 only) All logical drives in a spanned array must be either
write back or write through. That is, the write-cache mode settings for
the logical drives in the spanned array cannot be a mixture of write back
and write through.
2. (Failover environment only) A fault-tolerant controller pairing must be
configured as write through. This is because the logical drives are
configured as ″Shared.″ For more information, refer to the IBM
ServeRAID User’s Reference .
3. (Cluster environment only) If the logical drives are configured as
″Shared,″ the controllers must be configured as write through. For more
information, refer to the IBM ServeRAID User’s Reference .
1.
In the Logical devices view, click
(logical drive).
196 ServeRAID Manager Installation and User's Guide