Toshiba Magnia 560S - Manual (Page 154)

Logical Drives 136
WebBIOS Configuration Utility
5. Select the Write Policy.
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.
6. Select the Cache Policy.
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
7. Enable or disable the spanning mode for the current logical drive.
If enabled, the logical drive can occupy space in more than one array. If disabled,
the logical drive can occupy space in only one array.
For two arrays to be spannable, they must have the same stripe width (they must
contain the same number of physical drives) and must be consecutively numbered.
For example, assuming Array 2 contains four disk drives, it can be spanned only
with Array 1 and/or Array 3, and only if Arrays 1 and 3 also contain four disk drives.
If the two criteria for spanning are met, MegaRAID automatically allows spanning.
If the criteria are not met, the Span setting makes no difference for the current
logical drive.
8. Select a RAID level and press to confirm. See Chapter 3, RAID Levels for
your board for an explanation of the RAID levels.
9. Select the size of the logical drive, in MB.
10. Click on Accept to accept the changes or the Reset button to delete the changes and
return to the previous settings.
Configuration Preview
Step 5/5 displays a preview of the configuration that you created. Click Accept to save
the configuration or Back to return to the previous screens and change the
configuration.