Owner manual

Agent information 49
• Rebuild Blocks Left—Displays the number of blocks of data that still need to be redistributed. When the
value reaches 0, the rebuilding process is complete. The array continues to operate in interim recovery
mode while the drive is rebuilding.
• Rebuilding Drive—Identifies the physical drive that failed. The logical drive is rebuilding using a spare drive
in place of this failed drive.
When the status is Expanding one of the following values displays to indicate the progress of the expansion.
• Percent Expand Complete—Displays the percent complete of the expansion. When a logical volume is
expanding, the drive must redistribute the logical volume data across the physical drives. When the value
reaches 100, the expansion process is complete.
• Expand Blocks Left—Displays the number of blocks of data that still need to be redistributed. When the
value reaches 0, the expansion process is complete. The array continues to operate normally while the drive
is expanding.
• Fault Tolerance—Displays the fault tolerance mode of the logical drive. To change the fault tolerance mode,
run the Array Configuration Utility.
The following values are valid for the Logical Drive Fault Tolerance:
• None—(RAID 0) fault tolerance is not enabled. If a physical drive reports an error, the data cannot be
recovered by the Drive Array.
• Mirroring—(RAID 1/RAID 0+1) is the highest level of fault tolerance. It is the only method offering fault
tolerance protection if no more than two physical drives are selected. Drive mirroring creates fault
tolerance by storing duplicate data on two drives. There must be an even number of drives. This is the
most costly fault tolerance method because it requires 50 percent of the drive capacity to store the
redundant data.
• Data Guarding—(RAID 4) assures data reliability while using only a small percent of the logical drive
storage capacity. A designated, single physical drive contains parity data. If a drive fails, the controller
uses the data on the parity drive and the data on the remaining drives to reconstruct data from the
failed drive. This allows the system to continue operating with slightly reduced performance until you
replace the drive.
• Distributed Data Guarding—(RAID 5) stores parity data across all the physical drives in the array and
allows more simultaneous read operations and higher performance than data guarding (RAID 4). If a
drive fails, the controller uses the parity data and the data on the remaining drives to reconstruct data
from the failed drive. The system then continues operating with a slightly reduced performance until you
replace the failed drive.
• Advanced Data Guarding—(RAID 6) is the fault tolerance method that provides the highest level of data
protection. It stripes data and parity across all the physical drives in the configuration to ensure the
uninterrupted availability of uncorrupted data. This fault-tolerance method is similar to RAID 5 in that
parity data is distributed across all drives in the array, except in RAID ADG the capacity of multiple
drives is used to store parity data. Assuming the capacity of 2 drives is used for parity data, this allows
continued operation despite simultaneous failure of any 2 drives in the array, whereas RAID 4 and
RAID 5 can only sustain failure of a single drive.
• RAID 50—Distributed data guarding (RAID 5) with multiple parity groups.
• RAID 60—Advanced data guarding (RAID 6) with multiple parity groups.
• Unknown—You may need to upgrade your software.
• Capacity—Displays the size of the logical drive.
• Accelerator—Indicates whether the logical drive has an Array Accelerator board configured and enabled. The
following values are valid:
• Enabled—The Array Accelerator board is configured and enabled for this logical drive.
• Disabled—The Array Accelerator board is configured but not enabled for this logical drive.
• Unavailable—There is no Array Accelerator board configured for this logical drive.
• Unknown—The Storage Agents do not recognize the Array Accelerator board. You may need to upgrade
your software.
• Stripe Size—Displays the size of a logical drive stripe in kilobytes.
• Total Read and Write Requests—Displays the total number of read and write requests for the logical volume,
expressed in reads and writes per second.
• Reads—Displays the number of read requests for the logical volume, expressed in reads per second.
• Writes—Displays the number of write requests for the logical volume, expressed in writes per second.
• Sectors Read—Displays the number of sectors read for the logical volume for this interval. This value is
expressed in sectors per second.