Sonnet Technologies Fusion RAID Configuration Tool and Utilities Operation Manual - Manual (Page 19)

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2. Select RAID Management > Properties from the application
menu, and then view or change the current properties:
• Speed Read specifies the cache policy to be used during
read operations. Once a read command is given, the
ExpressSAS RAID code retrieves the next set of sequential
data from the RAID group’s drives and caches it in the
Sonnet RAID controller’s internal memory. If you select
Never, read caching is never performed. If you select
Always, read caching is always performed. If you select
Adaptive, Speed Read is enabled or disabled depending on
the sequential patterns detected in I/O requests.
• Auto Rebuild controls the replacement of a faulted
drive with any available unallocated drive. When you
click the Auto Rebuild check box and the Accept button,
Auto Rebuild is enabled. If a drive becomes faulted, the
ExpressSAS RAID adapter replaces the drive with an
unallocated drive.
• Rebuild Priority specifies the ratio of rebuild I/O activity
to host I/O activity. A rebuild priority of Same (default
value) indicates that rebuild I/O and host I/O are treated
equally. A rebuild priority of Low indicates that host I/O is
given a higher priority than rebuild I/O. A rebuild priority
of High indicates that rebuild I/O is given a higher priority
than host I/O. In practical terms, selecting Low enables
you to continue working with full read performance, but
the rebuild will take much more time to complete.
• Prefetch specifies the number of stripes that are read when
Speed Read is enabled or set to adaptive. The valid values
for prefetch are 0, 1, 2, 3, 4, 5 and 6; the default value is 1.
This property can only be changed after the RAID group is
created. To access this property, select the RAID group and
view its properties.
3. Click Accept.
1.2 RAID Group Setup and Management
RAID Group RAID Level Migration
Changing a RAID group from one RAID level to another is called
migration. The following migration levels are supported:
• JBOD to RAID Level 0
• JBOD to RAID Level 1
• RAID Level 0 to RAID Level 10
• RAID Level 1 to RAID 10
Select RAID Management > Migrate RAID Level from the
application menu, and then follow the instructions on the screen.
RAID Group Deletion
You may delete a group using the ATTO Configuration Tool.
Select RAID Management > Delete Group from the application
menu, and then follow the instructions on the screen.
RAID Group Rebuilding
If a RAID group becomes compromised, you must rebuild it.
Select RAID Management > Rebuild Group from the application
menu, and then follow the instructions on the screen.
You may pause a RAID group rebuild by selecting the RAID
group in the lower pane, and then selecting RAID Management >
Pause Rebuild from the application menu. To resume the rebuild,
select the RAID group in the bottom pane, and then select RAID
Management > Resume Rebuild from the application menu.
RAID Group Properties Modification
Each RAID group has specific properties, and the value of each
property remains with the RAID group when it is moved from
one computer to another. Some of the properties can only be
specified during RAID group creation (RAID level, interleave, and
sector size), whereas others may be changed at any time during
the life of the RAID group. See
Figure 15 on page 16.
1. Select a RAID group in the Groups pane.
WARNING: Data can be compromised or lost when
deleting storage or rearranging storage configurations.
Support Note: A RAID group rebuild may take several
hours to complete, depending on the operating system,
drive capacities, and RAID configuration.