MITIGACIÓN DE IMPACTO AMBIENTAL DE CURTIEMBRES

You can specify the cache memory settings for a single virtual disk or for multiple virtual disks in a storage array.

Guidelines to change cache settings for a virtual disk:

• After opening the Change Cache Settings dialog, the system may display a window indicating that the

RAID controller module has temporarily suspended caching operations. This action may occur when a new battery is charging, when a RAID controller module has been removed, or if a mismatch in cache sizes has been detected by the RAID controller module. After the condition has cleared, the cache properties selected in the dialog become active. If the selected cache properties do not become active, contact your Technical Support representative.

• If you select more than one virtual disk, the cache settings default to no settings selected. The current cache settings appear only if you select a single virtual disk.

• If you change the cache settings by using this option, the priority of all of the virtual disks that you selected is modified.

To change the virtual disk cache settings:

1. In the AMW, select the Storage & Copy Services tab and select a virtual disk.

2. In the menu bar, select Storage → Virtual Disk → Change → Cache Settings.

The Change Cache Settings window is displayed.

3. Select one or more virtual disks.

To select nonadjacent virtual disks, press <Ctrl> click. To select adjacent virtual disks, press <Shift> click. To select all of the available virtual disks, select Select All.

4. In the Cache Properties area, you can select:

• Enable read caching

• Enable write caching

– Enable write caching without batteries — to permit write caching to continue even if the RAID controller module batteries are discharged completely, not fully charged, or are not present.

– Enable write caching with replication — to replicate cached data across two redundant RAID controller modules that have the same cache size.

• Enable dynamic cache read prefetch

CAUTION: Possible loss of data—Selecting the Enable write caching without batteries option lets write caching continue even when the batteries are discharged completely or are not fully charged. Typically, write caching is turned off temporarily by the RAID controller module until the batteries are charged. If you select this option and do not have a universal power supply for protection, you could lose data. In addition, you could lose data if you do not have RAID controller module batteries and you select the Enable write caching without batteries option.

NOTE: When the Optional RAID controller module batteries option is enabled, the Enable write caching does not appear. The Enable write caching without batteries is still available, but it is not checked by default.

NOTE: Cache is automatically flushed after the Enable write caching check box is disabled.

5. Click OK.

A message prompts you to confirm the change in the virtual disk modification priority.

6. Click Yes.

7. Click OK.

The Change Virtual Disk Propreties - Progress dialog is displayed.

Changing The Segment Size Of A Virtual Disk

You can change the segment size on a selected virtual disk. During this operation, I/O performance is affected, but your data remains available.

Follow these guidelines to proceed with changing the segment size: • You cannot cancel this operation after it starts.

• Do not start this operation unless the disk group is in Optimal status.

• The MD Storage Manager determines the segment size transitions that are allowed. Segment sizes that are inappropriate transitions from the current segment size are unavailable on the menu. Allowed transitions usually are double or half of current segment size. For example, if the current virtual disk segment size is 32 KB, a new virtual disk segment size of either 16 KB or 64 KB is allowed.

NOTE: The operation to change the segment size is slower than other modification operations (for example, changing RAID levels or adding free capacity to a disk group). This slowness is the result of how the data is reorganized and the temporary internal backup procedures that occur during the operation.

The amount of time that a change segment size operation takes depends on: • The I/O load from the host

• The modification priority of the virtual disk • The number of physical disks in the disk group • The number of physical disk ports

• The processing power of the storage array RAID controller modules

If you want this operation to complete faster, you can change the modification priority to the highest level, although this may decrease system I/O performance.

To change the segment size of a virtual disk:

1. In the AMW, select the Storage & Copy Services tab and select a virtual disk.

2. From the menu bar, select Storage → Virtual Disk → Change → Segment Size.

3. Select the required segment size.

A message prompts you to confirm the selected segment size.

4. Click Yes.

The segment size modification operation begins. The virtual disk icon in the Details pane shows an Operation in Progress status while the operation is taking place.

NOTE: To view the progress or change the priority of the modification operation, select a virtual

disk in the disk group, and from the menu bar, select Storage → Virtual Disk → Change →