SnapProtect – Hitachi Data Systems (HDS) – Configuration

Set Up the Array Information

Provide the identification information for the array to ensure access.

Before using the new CCI based engine for HDS, ensure that all the snapshots and clones created with the HDvM based engine are deleted using the snap GUI.

The following section provides step-by-step instructions for setting up the array information.

  1. From the CommCell Browser, click the Storage tab and then click the Array Management icon.
  2. In the Array Management dialog box, click Add.

Select  HDS from the Snap Vendor list.

Specify the serial number of the array in the Name field.

For reference purposes, the screenshot below shows the serial number for the HDS storage device.

  1. In the Control Host box, type the IP address or host name of the Device Manager Server.

    Control host is not applicable for CCI based engines. Type N/A for such engines.

    Click Change and enter the access information of a user with administrative privileges in the Username and Password fields in Enter User Name and Password dialog box.

    The user must have Modify and View permissions for the device manager.

    Control Host is not applicable for CCI based engines, either for Available Array or for Associated Array.

    Use the Description field to enter a description about the entity. This description can include information about the entity's content, cautionary notes, etc.

    Click OK to save the information.

    Do not use any special character like '$'  in the password, which might cause failure to log in.

  2. Click the Snap Configuration tab and configure the following:

    For HDS with HDvM

    Specify the Storage Device group using the format <label>-<poolid>. For ShadowImage job, select SVOL matching the label and the poolid used for COW operation.

    Select Use devices only from this group only for SI jobs that force the device from device group with the label match.

    Select Enable Incremental Re-Sync of ShadowImage Pairs using aged clones to enable incremental resynch of ShadowImage pairs created and aged by HDS SnapProtect.

    Select Always select DP volumes as SVOL.

    Select Name of HDvM client as visible in HDvM server if it differs from the client name, only applicable to the source host.

    Name of HDvM client as visible in HDvM server if it differs from the client name does not work for proxy backup jobs. For proxy hosts, whose hostname and the name visible on HDVM server differ, refer Troubleshooting to set the registry on proxy host.

    Click OK.

    For HDS Using CCI Engine

    SVOL LDEV nickname: Limit the nickname to 20 characters. Name should have alphanumeric, or _(underscore), or –(hyphen) special characters. Name should not start with “IS_”. TI and SI jobs will pick SVOLs matching this name.

    CU range to be used to pick SVOLs: TI and SI Jobs will pick SVOLs in this CU range.

    Create VVOL for Thin Image: TI snapshot VVOLS will be create automatically.

    TI pool to be used for SVOLs: TI snapshot data will be created in this TI pool.

    DP pool to be used for SVOLs: SI SVOLs will be picked from this DP pool.

    Always select DP volumes as SVOLs: Only DP volumes will be picked as SI SVOLs.

    Use preexisting clones: Job will pick SI pairs created by user.

    Enable incremental resync using aged clones: Enable incremental resync of SI pairs created and aged by HDS SnapProtect.

    Enable Quick Resync capabilities: SI pairs will be managed using “HDS quick resync” option.

    Enable Quick Restore capabilities: SI pairs hardware restore will be performed using “HDS quick restore” option.

    HostGroup to which SVOLs will be presented: By default SVOLs are mapped to the hostgroup where command device is mapped to. To override this, set the hostgroup name using <port>-<name> format. Ex: CL1-A-myhostgroup. SVOLs will be presented to this hostgroup during map phase. If proxy host is involved, specify proxy host’s hostgroup. GUI mount operation will not use this host group. Refer Advanced for more information on GUI mount.

    Enable command logging for troubleshooting: CCI command output will be saved in <base>/temp folder for troubleshooting purposes.

    HORCM installation Home Directory Path: Full path where CCI commands are installed.

    HORCM instance number to be used for Raidcom commands: Specify user created HORCM instance number to be used by Raidcom commands.

    Remote Snap MA: Provide the client name of the MediaAgent to be designated as the remote Snap MA to enable Remote Snap MA.

    Perform snap of an existing clone: Select this option to take a TI snap on a SI SVOL instead of PVOL.

Additional Configuration for Snap of Clone

A traditional TI snap is associated with a PVOL (volume used for production data). Once the snap is taken, the TI VVOLs share the data blocks with PVOLs until there is a writing operation on the PVOL. There is a couple of drawbacks with such configuration.

  • Read operations from TI snaps may have a performance impact on the PVOLs
  • A catastrophic failure on PVOL will also corrupt the VVOL data and restores from the VVOL might not be possible

To overcome these limitations, HDS CCI engine provides a way to take periodic TI snaps from a SI SVOL:

The SVOL used during the snap backup should be in a SI relationship with the PVOL.

Once the SI relationship is established, the snap of clone feature can be enabled by selecting the Snap Configuration Perform snap of an existing clone.

During the first snap backup, the first available mirror unit will be picked and will be labeled as IS_SVOL_CASCADE. Subsequent TI snap backup jobs will pick the same SVOL using this label.

When the SVOL is selected, it will be synchronized with the PVOL and a TI snap will be taken off the SVOL. All subsequent operations like mount, backup copy, etc., will use the TI snap.

The SI will remain in a suspended (PSUS) state till the next snap backup.

Some of the limitations of using this feature are listed below.

  • All PVOLs belonging to a SubClient should already have at least one SI clone. All the clones should be part of the same Mirror unit number.
  • A PVOL should not be used in more than one subclient (even across different backupset.)
  • Revert is not supported.
  • Both SI and TI pairs will be SPLIT in the create phase of snap backup. This phase is within the VSS backup window. On certain Windows setups, the splits may take more than 10 seconds, resulting in VSS timeout.
  • The SI SVOL with label IS_SVOL_CASCADE will never be deleted even if the TI snaps are deleted and will remain in SI relationship forever.