Toshiba Magnia 560S - Manual (Page 129)

Configuring Arrays and Logical Drives
MegaRAID BIOS Configuration Utility
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12. Move the cursor to Size and press <Enter> to set the logical drive size.
By default, the logical drive size is set to all available space in the array(s) being
associated with the current logical drive, accounting for the Span setting and for
partially used array space. For example, if the previous logical drive used only a
part of the space in an array, the current logical drive size is set to the remaining
space by default.
13. Open the Advanced menu to set the remaining options.
14. Set the Stripe Size on the Advanced Menu.
Stripe size specifies the size of the segments written to each disk in a RAID 0, 5, 10,
or 50 logical drive. You can set the stripe size to 2 KB, 4 KB, 8 KB, 16 KB, 32 KB,
64 KB, or 128 KB. A larger stripe size produces better read performance, especially
if your computer does mostly sequential reads. If you are sure that your computer
does random read requests more often, choose a small stripe size. The default is 64
KB.
15. Set the Write Policy on the Advanced Menu.
Write Policy sets the caching method to write-back or write-through.
- In Write-back caching, the controller sends a data transfer completion signal to
the host when the controller cache has received all the data in a transaction. This
is the default setting.
- In Write-through caching, the controller sends a data transfer completion signal
to the host when the disk subsystem has received all the data in a transaction.
Write-through caching has a data security advantage over write-back caching.
Write-back caching has a performance advantage over write-through caching.
16. Set the Read-ahead Policy on the Advanced Menu.
Read-policy enables the SCSI read-ahead feature for the logical drive. You can set
this parameter to Normal, Read-ahead, or Adaptive.
- Normal specifies that the controller does not use read-ahead for the current
logical drive.
- Read-ahead specifies that the controller uses read-ahead for the current logical
drive.
- Adaptive specifies that the controller begins using read-ahead if the two most
recent disk accesses occurred in sequential sectors. If all read requests are
random, the algorithm reverts to Normal; however, all requests are still
evaluated for possible sequential operation. This is the default setting.
17. Set the Cache Policy on the Advanced Menu.
Cache Policy This parameter applies to reads on a specific logical drive. It does not
affect the Read ahead cache.
- Cached I/O specifies that all reads are buffered in cache memory. This is the
default setting.
- Direct I/O specifies that reads are not buffered in cache memory. Direct I/O
does not override the cache policy settings. Data is transferred to cache and the
host concurrently. If the same data block is read again, it comes from cache
memory.
18. Press <Esc> to exit the Advanced Menu.