Clear Cache

Overview

This function clears all of the data on the CM cache memory, data on the Extreme Cache, and data on the Extreme Cache Pool (hereinafter collectively referred to as "cache data").

This function is used when monitoring the system performance.

Cache Data to be Cleared

  • Read data on the CM, Extreme Cache (*1), and Extreme Cache Pool (*2)

  • Multiple cache data to be cleared can be selected from "CM", "Extreme Cache (*1)", and "Extreme Cache Pool (*2)".

    *1  :  This can be cleared when "Extreme Cache" is enabled for the storage system.
    *2  :  This can be cleared when "Extreme Cache Pool" is enabled for the storage system.
Caution

  • Stopping all host access is recommended before using this function.

  • If this function is used during operation, system performance may be temporarily reduced due to clearing the cache data. Make sure to check the access status to the storage system before using this function.

  • Stop the performance monitoring before using this function. If this function is used during a performance monitoring, the system performance (IOPS, throughput, response time, and cache hit rate) may temporarily and significantly be increased or decreased.

  • This function is not available in a Unified Storage environment.

  • If Dirty data (cache data that is not written back to the drive) exists in the cache memory, this function cannot be used. Stop the host access, and after waiting for the Dirty data to be written back to the drive (the Cache LED turns off), execute this function.

  • This function cannot be used under the following conditions:

    • The CM status is not "Normal"

    • The PFM status is not "Normal" (when selecting "Extreme Cache")

    • The status of RAID groups registered as Extreme Cache Pools is not "Available" (when selecting Extreme Cache Pool)

Note

  • This function deletes the cache data for Read, however the same data is stored in the drive so there is no data loss.

  • Cache data in the Extreme Cache can only be cleared when all of the following conditions are satisfied:

    • The ETERNUS DX500 S5/DX600 S5/DX900 S5 or the ETERNUS DX8900 S4 is used

    • PFMs are installed in CEs

    • The Extreme Cache is enabled

    • The Extreme Cache capacity has been specified (other than "0.0 TB")

  • Cache data in the Extreme Cache Pool can only be cleared when all of the following conditions are satisfied:

    • The ETERNUS DX100 S5/DX200 S5 is used

    • The Extreme Cache Pool is enabled

    • The Extreme Cache Pool memory size has been specified (other than "0 GB")

User Privileges

Availability of Executions in the Default Role

Default role Availability of executions
Monitor  
Admin
StorageAdmin  
AccountAdmin  
SecurityAdmin  
Maintainer

Refer to "User Roles and Policies" for details on the policies and roles.

Settings

Target Cache Settings

Item Description Setting values

Target Cache

Select the cache to clear.

  • CM

  • Extreme Cache (*1)

  • Extreme Cache Pool (*2)

*1  :  This item is only displayed when Extreme Cache is enabled.
*2  :  This item is only displayed when Extreme Cache Pool is enabled.

CM

Selected: Clear the cache (Default)

Cleared: Does not clear the cache

Extreme Cache

Selected: Clear the cache (Default)

Cleared: Does not clear the cache

Extreme Cache Pool

Selected: Clear the cache (Default)

Cleared: Does not clear the cache

Operating Procedures

  1. Click [Clear Cache] in [Action].

  2. Select the cache to clear and click the [Clear] button.

    → A confirmation screen appears.

    Caution

    • When an Extreme Cache or an Extreme Cache Pool is selected and the clear conditions are not satisfied, an error occurs.

  3. Click the [OK] button.

    → The cache data is cleared.

    Caution
    • An error occurs in the following conditions:

      • The system or CM status is not normal

      • The PFM status is not normal (when selecting "Extreme Cache")

      • The status of RAID groups registered as Extreme Cache Pools is not normal (when selecting "Extreme Cache Pool")

      • Dirty data exists in the cache memory

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