Setup Extreme Cache Pool

Overview

This function is used to perform the following settings for Extreme Cache Pool.

  • The Extreme Cache Pool setting (enabled or disabled)

  • The Extreme Cache Pool capacity setting

  • Tuning parameters

The maximum value that can be specified for a single CM is 12.8 TB. This value varies depending on the allocated drive capacity.

Extreme Cache Pool stores data in the RAID group that is controlled by the CM.

Caution
  • Extreme Cache Pool does not work when operating in an environment with a high cache hit rate.
  • Extreme Cache Pool cannot be enabled under the following conditions:
    • Pinned data exists in the storage system
    • A CM that is not in the "Normal" state exists
  • If an Extreme Cache Pool includes a RAID group without an "Available" state, the setting values and mode of the tuning parameter cannot be changed.
  • The Extreme Cache Pool function uses NVMe SSDs (and NVMe SSD SEDs) as secondary cache memory. Note that value-type SSDs cannot be used as secondary cache memory of the Extreme Cache Pool function.
Note
  • The Extreme Cache Pool setting (enabled or disabled), the memory size, and the tuning parameters can be changed during business operations.
  • The Extreme Cache Pool mode (enabled or disabled) of the storage system and the set states of Extreme Cache Pool for each volume are not linked. Regardless of the mode of the Extreme Cache Pool for the storage system, the default state of Extreme Cache Pool for each volume is "Enable".
  • Regardless of whether the Extreme Cache Pool is enabled (or disabled) for each volume, External Volumes do not use the Extreme Cache Pool.
  • The cache hit rate of Extreme Cache Pool for each volume can be checked in the [Performance Information] screen. Refer to the [Performance (Host I/O)] function or the [Performance (Advanced Copy)] function for details.
  • RAID groups that are used as Extreme Cache Pools are configured with RAID0 that has a single drive.
  • If multiple CMs are installed in the storage system, setting the same Extreme Cache Pool capacity for each CM is recommended.
  • Enabling or disabling Extreme Cache Pool for each volume can be performed. Refer to the [Modify Cache Parameters] function for details.
  • Extreme Cache Pool for the relevant volume can be used when the Extreme Cache Pool for the storage system and the Extreme Cache Pool for the volume are both enabled.
  • To stop using Extreme Cache Pools, release Extreme Cache Pool. Refer to the [Release Extreme Cache Pool] function for details.

Settings (Extreme Cache Pool Settings)

Extreme Cache Pool Settings

Item Description Setting values
Mode Select whether to enable or disable the Extreme Cache Pool for the storage system.

Enable

Disable (Default)

Settings (Extreme Cache Pool Capacity Settings)

Extreme Cache Pool Capacity Settings

Item Description Setting values
CM

All the CMs in the storage system are displayed.

CM#n or CE#n CM#n

  
Capacity

The Extreme Cache Pool capacity that is to be set to the relevant CM is displayed.

If the Extreme Cache Pool capacity is not specified, "0 TB" is displayed.

  

Encryption by CM

Select the encryption status of the Extreme Cache Pool area in the relevant CM.

  • On

    Create an Extreme Cache Pool area that is encrypted by CM.

  • Off

    Create an Extreme Cache Pool area that is not encrypted by CM.

To use an Extreme Cache Pool as secondary cache memory for encrypted volumes, select "On" for this item.

This mode is available only when the encryption mode is enabled.

Caution
  • If the Extreme Cache Pool areas are not encrypted even when encrypted volumes are included in the volumes that are controlled by the relevant CM, Extreme Cache Pools cannot be used as secondary cache memory for I/O to the encrypted volumes.
  • If the volumes controlled by the relevant CM are all unencrypted, encrypting the Extreme Cache Pool area is not required.
  • SED type drives cannot be selected if "On" is selected for this item.

On

Off (Default)
Member Drives

The location information of the drives that are used as Extreme Cache Pool areas to be set in the relevant CM is displayed. If no drives are selected, "Not specified" is displayed.

CE Slot#n

DE#n Slot#n

  

[Tabular] Tab

Click the [Tabular] tab to select drives from the list. A list of unused drives (NVMe SSD or NVMe SSD SED) is displayed.

Item Description
Checkbox to select drives

Select the checkboxes for the drives to be used in the RAID groups that configure an Extreme Cache Pool.

The checkbox is selected for a drive that has already been selected as the Extreme Cache Pool area.

Caution
  • Note that drives smaller than 1600 GB cannot be specified to be used as the Extreme Cache Pool area.
  • Up to eight drives can be specified for a single CM.
  • Up to 12.8 TB of the Extreme Cache Pool area can be specified for a single CM.

Refer to "Drive Selection" ([Tabular] Tab) in the [Create RAID Group] function for display items.

[Graphic] Tab

Click the [Graphic] tab to select drives from the drive installation image. The installation images of all the drives installed in the storage system are displayed. Checkboxes are displayed for unused drives (NVMe SSDs or NVMe SSD SEDs).

Item Description
DE selection list box

Select the DE group.

DE groups are displayed as options in the list box when at least one CE or DE in the DE group is installed in the storage system.
Checkbox to select drives

Select the checkboxes for the drives to be used in the RAID groups that configure an Extreme Cache Pool.

The checkbox is selected for a drive that has already been selected as the Extreme Cache Pool area.

Caution
  • Note that drives smaller than 1600 GB cannot be specified to be used as the Extreme Cache Pool area.
  • Up to eight drives can be specified for a single CM.
  • Up to 12.8 TB of the Extreme Cache Pool area can be specified for a single CM.

Refer to "Drive Selection" ([Graphic] Tab) in the [Create RAID Group] function for display items.

Settings (Tuning Parameter Settings)

Tuning Parameter Settings

Item Description Setting values

Initial Caching Threshold

Specify the threshold that affects how frequently data is stored in Extreme Cache Pool.

The greater the value is, the less frequently data is stored in Extreme Cache Pool. The smaller the value is, the more frequently data is stored in Extreme Cache Pool.

If the set value is exceeded, it is assumed that the relevant data is read frequently and the data is stored in Extreme Cache Pool.

This parameter specifies the threshold value that is used until the Extreme Cache Pool memory is full after Extreme Cache Pool is enabled.

Caution

  • This parameter is used for performance tuning. It is not necessary to change the default setting (1) for normal use.

1 (Default) -16

Caching Threshold

Similar to "Initial Caching Threshold", this parameter specifies the threshold that affects how frequently data is stored in Extreme Cache Pool.

If the set value is exceeded, it is assumed that the relevant data is read frequently and the data is stored in Extreme Cache Pool.

This threshold value is used after the Extreme Cache Pool memory is full.

Caution

  • This parameter is used for performance tuning. It is not necessary to change the default setting (5) for normal use.

  • This item is available only when the "Not relocate Cache Data" checkbox is cleared (cache data is relocated).

1 - 16

5 (Default)

"Not relocate Cache Data" checkbox

Select or clear the "Not relocate Cache Data" checkbox.

If the checkbox is selected, new data is not stored (relocated) after the Extreme Cache Pool memory is full.

If the checkbox is cleared, the storage system chronologically deletes the stored data from Extreme Cache Pool beginning with the oldest and stores (relocates) new data.

If the data is not relocated, select the checkbox

If the data is relocated, clear the checkbox (Default)

Caching Priority

Specify the concurrency of the staging process when data is stored in Extreme Cache Pool.

The greater the value is, the higher the concurrency is set for storing data in Extreme Cache Pool. The smaller the value is, the lower the concurrency is set for storing data in Extreme Cache Pool.

Caution

  • This parameter is used for performance tuning. It is not necessary to change the default value ("10 (Fastest)") for normal use.

10 (Fastest) (Default)

9

8

7

6

5

4

3

2

1

Monitoring I/O

Select the I/O type for storing data in Extreme Cache Pool.

Read (Default)

Read / Write

Operating Procedures

When Enabling Extreme Cache Pool

  1. Click [Setup Extreme Cache Pool] in [Action].

    Note
    • To change the tuning parameters only, proceed to Step 4. The [Set] button can be clicked even if "Mode" is "Enable".

  2. Select "Enable" for "Mode".

  3. Click the [Member Drives] button.

    Select drives from the list or the installation image to configure an Extreme Cache Pool, and click the [OK] button.

    → Returns to the [Extreme Cache Pool Settings] screen.

  4. If required, specify the tuning parameters and then click the [Set] button.

    → A confirmation screen appears.

  5. Click the [OK] button.

    → The setting of Extreme Cache Pool starts.

  6. Click the [Done] button to return to the [Extreme Cache Pool] screen.

When Disabling the Extreme Cache Pool

Note

  • To disable the Extreme Cache Pool, set the Extreme Cache Pool capacity to "0 TB" in advance. Refer to the [Release Extreme Cache Pool] function for details.

  1. Click [Setup Extreme Cache Pool] in [Action].

  2. Select "Disable" for "Mode" and click the [Set] button.

    → A confirmation screen appears.

    Note
    • The tuning parameters remain even when the Extreme Cache Pool mode is changed from "Enable" to "Disable".

  3. Click the [OK] button.

    → The setting of Extreme Cache Pool starts.

  4. Click the [Done] button to return to the [Extreme Cache Pool] screen.