Set Thin Provisioning

Overview

This function enables or disables the use of the Thin Provisioning function and sets the maximum pool capacity that can be created in the storage system. The maximum pool capacity is the maximum total capacity for TPPs and FTRPs that can be created in the storage system. The chunk size is determined by the specified maximum pool capacity.

For the maximum pool capacity and determined chunk size for each model, refer to The Maximum Number of Pools, Maximum Pool Capacity, and Determined Chunk Size for Each Model.

Caution

  • If the following conditions are all satisfied, the Thin Provisioning function can be enabled.

  • The Thin Provisioning function cannot be disabled in the following conditions.

    • TPPs exist in the storage system

    • "TPV balancing" is selected for the Thin Provisioning allocation mode

    • The Automated Storage Tiering feature is enabled (*1)

      *1  :  Enabling or disabling the Automated Storage Tiering feature is performed by using ETERNUS SF Storage Cruiser.

  • Cache memory is not only used for the Thin Provisioning function (*1), but also used for copy tables, REC Buffers, the Storage Cluster function (*2), and the Non-disruptive Storage Migration function. Note that an REC Buffer with the maximum capacity for each model cannot always be created depending on the following conditions.

    • Memory capacity in the storage system

    • Copy table size

    • REC Buffer size

    • Total TFOV capacity (*2)

    • License registration for the Non-disruptive Storage Migration function

    *1  :  The shared area in the cache memory is used for the following conditions.

    • The maximum pool capacity has been expanded to "1.5 PB" or larger

    • The total TFOV capacity (*2) has been expanded from the default capacity

      Refer to the descriptions about "Storage Cluster" in the [System] screen for the default capacity of the TFOV for each model.
    *2  :  The total TFOV capacity indicates the total capacity of the volumes that are used for the Storage Cluster function in a storage system.

  • If the Virtual Volume function is enabled, the current state (enabled or disabled) of the Thin Provisioning function cannot be changed. To check whether the Virtual Volume function is enabled or disabled, use the [System] screen. Refer to the [System (Basic Information)] function for details.

  • The FTRP capacity that can be used as Virtual Volumes (VVOLs) is different from the maximum pool capacity. Refer to The Maximum FTRP Capacity that Can Be Used as VVOLs for details.

  • If the maximum pool capacity is set to "4 PB" or larger, the cache mode is temporarily changed to the "Write Through" mode. The workload I/O performance of the entire storage system is lowered when the cache mode is transitioning to "Write Through Mode". Therefore, it is recommended to set a maximum pool capacity of 4 PB or larger when the work I/O is low.

Note

  • If "Disable" is selected for the Thin Provisioning function, make sure to change the Thin Provisioning allocation mode from "TPV balancing" to the default "TPP balancing" setting. Refer to the [Setup Subsystem Parameters] function for details.

Installed Drives for Each Maximum Pool Capacity

The following drives must be installed for each maximum pool capacity. There are no requirements for drive type, capacity, and speed.

The following table shows the calculated values for the pool capacity. Note that the storage system configuration in this calculation may differ from actual environments.

Model Maximum pool capacity Number of installed drives

Installed drive location
Enclosures Slot location
ETERNUS DX600 S6 Up to 1 PB 2 CE#0 Slot#0 and Slot#1
DE#10 Slot#0 and Slot#1

1.5 PB

 4 CE#0 Slot#0 to Slot#3
CE#10 Slot#0 to Slot#3
96 PB 4 CE#0 Slot#0 to Slot#3
CE#10 Slot#0 to Slot#3

ETERNUS DX900 S6

ETERNUS DX8900 S6

 Up to 1 PB 2 CE#0 Slot#0 and Slot#1
DE#04 Slot#0 and Slot#1
2 PB 4 CE#0 Slot#0 to Slot#3
DE#04 Slot#0 to Slot#3
4 PB 8 CE#0 Slot#0 to Slot#3
DE#04 Slot#0 to Slot#3
DE#08 Slot#0 to Slot#3

8 PB

 16 CE#0 Slot#0 to Slot#7
DE#04 Slot#0 to Slot#7
DE#08 Slot#0 to Slot#7
512 PB 16 CE#0 Slot#0 to Slot#7
DE#04 Slot#0 to Slot#7
DE#08 Slot#0 to Slot#7

The Maximum FTRP Capacity that Can Be Used as VVOLs

Model The maximum FTRP capacity that can be used as VVOLs

ETERNUS DX600 S6

 1024 TB

ETERNUS DX900 S6

ETERNUS DX8900 S6

 2 PB
Caution

  • The actual available capacity that can be used as a VVOL is limited depending on whichever is smaller, the maximum FTRP capacity or the maximum pool capacity. For example, if the ETERNUS DX8900 S6 is used and the maximum pool capacity is "512 TB", the actual capacity that can be used for VVOLs is 512 TB even if the maximum FTRP capacity that can be used for VVOLs is "2 PB".

Settings

Thin Provisioning Settings

Item Description Setting values

Thin Provisioning

Select whether to "Enable" or "Disable" the Thin Provisioning function.

Enable

Disable (Default)

Maximum Pool Capacity

Select the maximum pool capacity that is specified for the storage system.

The maximum pool capacity can be expanded gradually according to the used pool capacity. Because the maximum pool capacity is not fixed, memory can be more effectively used. Note that if the chunk size is changed depending on the expanded "Maximum Pool Capacity", a calculation different from the existing method is used to obtain the pool capacity that can be created.

This item is only available when "Thin Provisioning" is enabled. Note that a capacity that is smaller than the current capacity cannot be selected.

Caution

  • The actual available capacity is limited if the maximum physical capacity of the drives that can be installed is smaller than the maximum pool capacity.

  • If the chunk size is changed due to the expansion of the maximum pool capacity and the maximum pool capacity has already been used up before the expansion, new pools cannot be created. For example, if the current maximum pool capacity in the ETERNUS DX8900 S6 is "8 PB", the capacity that can be used to create new pools is calculated with the following formula.

    Current maximum pool capacity (Chunk size a (*1))

    [A]

    Used pool capacity (Chunk size b (*2))

    [B]

    Capacity that can be used to create new pools

    [C]

    		 Description
    8 PB (21 MB) 1 PB (21 MB) 7 PB

    The capacity that can be used to create new pools [C] is calculated with the following formula.

    [C] = [A] - [B] × (Chunk size a / Chunk size b)
    8 PB (21 MB)

    0 PB

    ↑ New pools cannot be created
    *1  :  This indicates the chunk size that is determined according to the "Maximum Pool Capacity" that is to be set with this function. Refer to The Maximum Number of Pools, Maximum Pool Capacity, and Determined Chunk Size for Each Model for details.
    *2  :  This indicates the chunk size that is determined by the "Maximum Pool Capacity" that had been specified in the storage system when TPPs were created. The chunk size can be checked on the [Thin Provisioning Pool] screen. Refer to the [Thin Provisioning Pool (Basic Information)] function for details.
Note

  • To reduce the maximum pool capacity, disable "Thin Provisioning". After performing this action, restart this function to enable "Thin Provisioning", and then set a new "Maximum Pool Capacity".

ETERNUS DX600 S6:

512 TB (Default)

1 PB

1.5 PB

96 PB

ETERNUS DX900 S6 or the ETERNUS DX8900 S6:

512 TB (Default)

1 PB

2 PB

4 PB

8 PB

512 PB

Operating Procedures

  1. Click [Set Thin Provisioning] in [Action].

  2. Select whether to enable or disable the Thin Provisioning function, specify the maximum pool capacity, and then click the [Set] button.

    → A confirmation screen appears.

    Caution

    • If the Virtual Volume function is being used and the chunk size is changed as a result of a maximum pool capacity expansion, a warning message related to the Virtual Volume function appears.

  3. Click the [OK] button.

    → The Thin Provisioning setting starts.

  4. Click the [Done] button to return to the [Settings] screen.