Extent pools — Main page

Use this page to create new extent pools or to modify, delete, or view information about existing extent pools for a selected storage unit.

Introduction

The work area displays a drop-down list to select a storage unit and a multi selection table with a toolbar and a drop-down action list. The default table sort order is by extent pool nickname. If no extent pools exist, the table appears in the work area with the table toolbar, column headers and table footer but no rows of data.

Menu path

Real-time manager or Simulated manager > Configure storage > Extent pools

Fields

Select storage unit

The nicknames of storage units that are available for selection. This list includes any nickname that is associated with any storage unit that is currently displayed in the Storage units main page. The default value for this field is "None selected".

Select

The check boxes for selecting items in the table on which to perform actions on the extent pools displayed. The default value for this field is not selected.

Nickname

The user- or system-defined nickname for the extent pool, limited to 16 characters. The nickname is a link to the Extent Pool Properties page. You can change the values for the Nickname, Storage threshold, and Reserved storage attributes on the Extent Pool Properties page. Nicknames are created by the user when resources are created and are used as part of an overall scheme or naming convention for making resources easier to identify and manage.

Number

A 4-decimal digit extent pool number with no leading zeroes, prefixed by the letter P (for example, P5). Even numbered extent pools are associated with rank group 0. Odd numbered extent pools are associated with rank group 1.

Storage Type

The extents of the ranks are formatted in the architecture associated with the specified storage type. The extent pool storage type determines the volume storage type. One of the following values displays:

FB. These are fixed block extents - 1 GB. In fixed block architecture, the data (the logical volumes) are mapped over fixed-size blocks or sectors. Use the FB storage type for open-systems host volumes.
CKD. These are count-key-data extents - CKD Mod 1. In count-key-data architecture, the data field stores the user data. Use the CKD storage type for IBM^® eServer™ zSeries^® or S/390^® volumes.

RAID

The type of RAID that is used by the ranks in the extent pool. RAID is a methodology for grouping disk drives to protect against data loss from a failing disk drive. One of the following values is displayed:

RAID 5. A type of RAID that optimizes cost-effective performance while emphasizing use of available capacity through data striping. RAID 5 provides fault tolerance for up to two failed disk drives by distributing parity across all the disk drives in the array plus one parity disk drive.
RAID 10. A type of RAID that optimizes high performance while maintaining fault tolerance for up to two failed disk drives by striping volume data across several disk drives and mirroring the first set of disk drives to an identical set of disk drives.
Mixed. Is displayed only if you have assigned a rank to the extent pool and the array that was used to create the newly added rank has a different RAID type than the existing RAID type of the extent pool. The RAID type conversion operation might take some time to complete, and the RAID type remains Mixed until the conversion completes. The RAID type remains Mixed if you have chosen not to convert the RAID type of the newly added rank to ensure that all ranks in the extent pool have the same RAID type.
Not specified. Is displayed when no ranks have been assigned to the extent pool.

Primary Server

The server enclosure processor card of the storage unit from which the extent pool is accessed under normal operating conditions when both of the server enclosure processor cards are operating in dual mode. Each extent pool is defined to be accessed by only one primary server. Valid values are 0 and 1. The processor cards are located in the rear of the enclosure. One of the cards is below the rear operator panel and above the battery backup units. The other card is located below the battery backup units and above the system service card.

Ranks

The number of ranks that are assigned to the extent pool. The value is an integer between 0 and 128.

Total GB

The total amount of potentially usable storage in the extent pool in gigabytes.

Reserved %

The user-defined percentage of extents in the extent pool that the storage unit is not allowed to allocate. The value for Reserved % is an integer between 0 and 100. When the extent pool is created or modified, the field is named Reserved storage (%) and the default value is 0, which indicates that no extents are reserved. This value can be changed by the Modify... action or on the Extent Pool Properties page.

Available GB

The amount of storage in the extent pool that is not allocated and not reserved, in gigabytes.

Threshold Exceeded

A Yes or No value that indicates if the percentage of unavailable storage is greater than the Storage threshold percentage. The Storage threshold provides a warning when the percentage of unavailable space in the extent pool exceeds a user specified percentage. The Storage threshold is a user defined percentage of the total number of extents in the extent pool. The Storage threshold is an integer value between 0 and 100, and defaults to 100 if it is not specified when the extent pool is created. Unavailable GB is determined by subtracting Available GB from Total GB. The percentage of Unavailable GB is determined by dividing Unavailable GB by Total GB. Percentage of Unavailable GB is the percentage of storage in the extent pool that is no longer available for creating new volumes.

A "Yes" value for Threshold Exceeded indicates that the percentage of Unavailable GB is greater than the Storage threshold. A "No" value indicates that the percentage of Unavailable GB is less than or equal to the Storage threshold. The Threshold Exceeded value (Yes or No) is a link to the Extent Pool Properties page. You can change the values for the Nickname, Storage threshold and Reserved storage attributes on the Extent Pool Properties page.

Actions

Create...: This action is always available on this page. When you select Create..., the Create Extent Pool->Definition method page is displayed in the work area. This page is the first page of the Create Extent Pool wizard.
Delete: This action is available when you select one or more extent pools in the table. When you select Delete, a confirmation warning message is displayed. If you click Continue on the message, you delete the selected extent pool and any volumes that are configured from the selected extent pool.
Modify...: This action is available when you select one extent pool in the table. When you select Modify..., the Modify Extent Pool->Define properties page is displayed in the work area. This page is the first page of the Modify Extent Pool wizard. Use the Modify... action to change the nickname and Reserved storage for the selected extent pool.
Properties: This action is available when you select one extent pool in the table. When you select Properties, the Extent Pool Properties page displays the attributes of the selected extent pool and their corresponding values. You can change the values for all three of the displayed attributes on the Extent Pool Properties page, which are Nickname, Storage threshold, and Reserved storage.