Pool specifications and requirements

Pool capacity

Calculate pool capacity using the following formula:

Capacity of the pool (MB) = total-number-of-pages * 42 - 4200.

4200 in the formula is the management area size of the pool-VOL with System Area.

Total number of pages = Σ(floor(floor(pool-VOL number of blocks / 512) / 168)) for each pool-VOL.

floor( ): Truncates the value calculated from the formula in parentheses after the decimal point (that is, round down to nearest whole number).

Following are minimum and maximum capacity sizes for one pool:

• VSP G130: From 3.9 GB to 240 TB
• VSP G350 and VSP F350: From 3.9 GB to 4.0 PB
• VSP G370 and VSP F370: From 3.9 GB to 4.0 PB
• VSP G700 and VSP F700: From 3.9 GB to 4.0 PB
• VSP G900 and VSP F900: From 3.9 GB to 4.0 PB

Following are maximum capacity sizes of all pools in a storage system:

• VSP G130: 240 TB
• VSP G350 and VSP F350: 4.4 PB
• VSP G370 and VSP F370: 8.0 PB
• VSP G700 and VSP F700: 12.5 PB
• VSP G900 and VSP F900: 16.6 PB

If you operate a pool without monitoring the free space, then ensure that the total DP-VOLs capacity remains smaller than the pool capacity.

Max number of pool-VOLs

From 1 to 1,024 volumes (per pool).

A volume can be registered as a pool-VOL to one pool only.

Maximum number of pools

• VSP G130, VSP G350, VSP G370, VSP G700, VSP F350, VSP F370, VSP F700: Up to a total of 64 pools per storage system. Pool numbers (0 to 63) are assigned as pool identifiers.
• VSP G900 and VSP F900: Up to a total of 128 pools per storage system. Pool numbers (0 to 127) are assigned as pool identifiers.

The maximum number of pools includes the following pool types:

• Dynamic Provisioning (including Dynamic Tiering and active flash)
• Thin Image

Increasing capacity

You can increase pool capacity dynamically. Best practice is to add pool-VOLs to increase capacity by one or more parity groups.

Reducing capacity

You can reduce pool capacity by removing pool-VOLs.

Deleting

You can delete pools that are not associated with any DP-VOLs or with any Thin Image pairs or Thin Image snapshot data.

Thresholds

• Warning Threshold: You can set the value between 1% and 100%, in 1% increments. The default is 70%.
• Depletion Threshold: You can set the value between the Warning Threshold and 100%, in 1% increments. The default is 80%.

If the pool used-capacity is equal to or greater than the Warning Threshold or the Depletion Threshold, a service information message (SIM) is issued by the storage system. In addition, when the Depletion Threshold is reached, the following functions will no longer work:

• Pool rebalance
• Pool relocation
• Creation of DP-VOLs
• Creation of HTI pairs

Thresholds cannot be defined for a pool with data direct mapping enabled.

Data allocation unit

42 MB

The 42-MB page corresponds to a 42-MB continuous area of the DP-VOL. Pages are allocated for the pool volumes only when data has been written to the area of the DP-VOL.

Tier

(Dynamic Tiering and active flash)

Defined based on the media type (see Drive type for a Dynamic Tiering and active flash tier, below). Maximum 3 tiers.

Maximum capacity of each tier

(Dynamic Tiering and active flash)

• VSP G130: 240 TB (Total capacity of the tiers must be within 240 TB.)
• Virtual Storage Platform VSP G350, VSP G370, VSP G700, VSP G900, VSP F350, VSP F370, VSP F700, VSP F900: 4.0 PB (Total capacity of the tiers must be within 4.0 PB and the shared memory must be installed).