Virtual Disk Groups

In this topic:

About virtual disk groups

Creating groups

Adding virtual disks to existing groups

Serving groups to a host

Performing snapshot operations on groups

Performing rollback operations on groups

Performing replication operations on groups

Enabling/disabling sequential storage on groups

Renaming groups and virtual disks in groups

Removing virtual disks from groups

Deleting groups

Viewing group details

About Virtual Disk Groups

Virtual disks can be grouped in order to perform the same operations on all members of the group simultaneously. Any number of virtual disk groups can be created with an unlimited number of members, but any virtual disk can only be a member of one virtual disk group.

Virtual disk groups can contain virtual disks belonging to different servers in the same server group. In this case, each server will only recognize group members that were created from their own storage sources. Members of the virtual disk group will appear under their respective servers in the DataCore Servers panel. Actions will only be performed on the applicable virtual disks in the group. In order for the same action to be performed for all virtual disks in the group, the action may have to be performed for more than one server (depending on the configuration of the virtual disks in the group). One such action is enabling Continuous Data Protection.
Group operations can impact performance. The impact depends on the type of operation and the number of virtual disks in the group.
Snapshots, Continuous Data Protection and Sequential Storage cannot be enabled on a virtual disk group if the group has a member that is a VVOL or protocol endpoint virtual disk.

Group operations include:

Serving the group to a host
Performing snapshot operations
Enabling/disabling Continuous Data Protection and performing rollback operations
Performing replication operations
Enabling/disabling sequential storage
Renaming virtual disks in a group

Creating Groups

In the DataCore Servers panel, right-click on a virtual disk and point to Add to Group and then select Create Group.
The Create Virtual Disk Group dialog box opens. A default name is entered in the name field. Change the default group name and enter a description of the group if necessary.
From the list, select one or more virtual disks to add to the group.
Click Create.

After the group is created:

The virtual disk group appears in everywhere that individual virtual disks appear in the DataCore Management Console.
Virtual disk group actions are initiated in the same manner as other individual virtual disk actions.
A Virtual Disk Group details page is created for the group.

Adding Virtual Disks to Existing Groups

In the DataCore Servers panel, Host Panel or any virtual disk list, right-click on a virtual disk and point to Add to Group and then select the group.

If the virtual disk has snapshots or rollbacks, the snapshots and rollbacks will not be added to the group, only the virtual disk is added.

Serving Groups to a Host

Virtual disk groups can be served to hosts. The same wizard is used to serve virtual disks and virtual disk groups. Instead of selecting individual virtual disks, one or more virtual disk groups can be selected. Individual virtual disks from the group can also be selected and served. When serving multiple virtual disks in a group, a starting LUN can be selected and that number will be the starting LUN value to use when serving that group of virtual disks. For detailed instructions on serving virtual disks and groups, see Serving Virtual Disks. The operation can also be initiated from the DataCore Servers panel by right-clicking on a group and selecting Serve to Hosts.

When virtual disk groups are served, associated snapshots and rollbacks in the virtual disk group are not automatically served. They must be served individually.

Performing Snapshot Operations on Groups

To create a snapshot group of a virtual disk group:

In the Virtual Disk Group > Virtual Disk Group Actions, click Create Snapshot Group.

(Alternatively, snapshot operations can be initiated from context menus in panels and virtual disk lists.)
In the page that opens, a default name is provided for the snapshot. The default name consists of the name of the virtual disk group name and the timestamp (snapshot point) of when the snapshot was created. Change the name if desired. Add a description if desired.
Select the snapshot type:
- Differential - A logical image of the source virtual disk at the snapshot point. The snapshot is dependent on the source.
- Full - A clone copy of the source virtual disk at the snapshot point. After migration is successfully completed, the snapshot is fully usable and can exist and operate independently of the source from which it was created.
  Creating full copies requires more resources than creating differential copies. The load on the DataCore Server that is migrating data is dependent on the available resources of the server.
Only select the Duplicate disk identifier check box if both the source virtual disk and the snapshot will be served to hosts requiring the same SCSI inquiry ID (virtual product information). For instance, this is required for ESXi clusters.
Select the Assign ownership to me check box to assign exclusive ownership to the user account currently logged in and creating the snapshot. This restricts all operations on the snapshot to only the account logged in and the Administrator account.
In the list, select the snapshot properties and pool to use to create a snapshot for each virtual disk. click Create Disk Pool to create a new pool.
- Select the Profile. The default setting for the profile is inherited from the source virtual disk, select a different level if required. (See Storage Profiles for more information.)
- Select the Server where the snapshot should be created. The default setting for the server is set to the destination server of the preferred snapshot pool (if a preferred snapshot pool is set for virtual disk) or the first host of the virtual disk but can be changed if required.
  
  When the server is changed the Pool list the pools in the selected server.
- Select the Pool to use to create the snapshot or click Create Disk Pool to create a new pool.
  The default setting for the pool is set in the following order:
  - Preferred snapshot pool of the virtual disk.
  - Default snapshot pool of the primary server of the virtual disk.
  - The pool with the most free space in the primary server of the virtual disk.
- Select the Compress check box to enable compression on the snapshot. The compression option will be available when the virtual disk has encryption disabled and Pool has capacity optimization enabled.
  
  By default, compress will be selected when the virtual disk has inline deduplication or inline compression, and pool has capacity optimization enabled.
Click Create.

When a snapshot of a virtual disk group is created, the "snapshot group" will contain a snapshot of every virtual disk in the group.

After a snapshot group is created, additional snapshot operations such as: Update Snapshot, Promote to Full Snapshot, Revert from Snapshot, and Split Snapshot, can be performed on the snapshot group. Snapshots operations are performed in the same manner and with the same rules as a snapshot operation on an individual virtual disk. See Snapshot Operations for more information.

A snapshot group is listed under the source virtual disk group wherever it appears in the DataCore Management Console.

Detail pages will exist for snapshot groups and all individual snapshots in the snapshot group.

A mapstore pool is required to be set for all applicable DataCore Servers that are a storage source of virtual disks in the group.
When a snapshot group exists, all subsequent snapshot operations performed on that snapshot group must be performed at the snapshot group level, not on individual snapshots in the group. Group snapshot operations cannot be performed on snapshots of virtual disk members that are not members of the snapshot group.
Individual snapshots in the snapshot group may be deleted.
When a snapshot group is split, a new virtual disk group will be created and the resulting virtual disks will be added to the new group.
When a snapshot group is deleted, all snapshots in the group will also be deleted.
When a snapshot is created for a virtual disk group and a failure occurs that prohibits the creation of all snapshots for the group, then no snapshots will be created.
Also see Shared Multi-port Array Support for information about dual virtual disks.

Performing Rollback Operations on Groups

Continuous Data Protection (CDP) can be enabled for a virtual disk group and rollbacks can be created for the group. When a rollback is created for a virtual disk group, the "rollback group" will contain a rollback of every virtual disk in the group that has data protection enabled. After a rollback group is created, additional rollback operations (Revert from Rollback, Split Rollback) can be performed on the rollback group. Rollback group operations are performed in the same manner and with the same rules as a rollback operation on an individual virtual disk. See Continuous Data Protection Operations for more information.

A rollback group is listed under the source virtual disk group wherever it appears in the DataCore Management Console.

Detail pages will exist for every rollback group and all individual rollbacks in the rollback group.

Enabling and disabling CDP can be performed on the group or individually on members of a virtual disk group. In order to enable CDP at the group level, all group members must be eligible for CDP and not already have CDP enabled; otherwise, members must be enabled individually. See Continuous Data Protection Operations for eligibility requirements. If the group members are comprised of storage sources that do not have a common server, CDP will have to be enabled at the server level for each affected server.
Disabling CDP at the group level will disable all eligible group members on all servers. CDP cannot be disabled at the group level unless all group members are healthy.
When a rollback group is created, the earliest restore point for the virtual disk group will be the latest time any member of the group was enabled for CDP.
The Create Rollback operation will only be performed on applicable virtual disks in the group. Rollbacks are only created for those virtual disks that have CDP enabled for the same server that is selected when the rollback group is created.
For example, assume that a rollback group is created for VD Group 1 with ServerA selected. Rollbacks will not be created for any virtual disks in the group that have a different server selected for CDP.
While creating a rollback group, the Compressed check box will be unavailable if:
- the selected destination pool has Capacity Optimization disabled.
- any of the source virtual disks have encryption enabled.
When a rollback group exists, all subsequent rollback operations performed on that rollback group must be performed at the rollback group level, not on individual rollbacks in the rollback group. Group rollback operations cannot be performed on existing rollbacks of virtual disk members that are not members of a rollback group.
Individual rollbacks in the rollback group may be deleted.
When a rollback group is split, a new virtual disk group will be created and the resulting virtual disks will be added to the new group.
When a rollback group is deleted, all rollbacks in the group will also be deleted.
When a rollback is created for a virtual disk group and a failure occurs that prohibits the creation of all rollbacks for the group, then no rollbacks will be created.

Performing Replication Operations on Groups

When replications are created for virtual disks in a group, additional replication operations can be performed at the virtual disk group level. Operations include activating or deactivating virtual disks, pausing or resuming transfers, marking checkpoints, and splitting replications. Replication operations are performed in the same manner and with the same rules as a replication operation on an individual virtual disk. See Replication Operations for more information. Replication operations can also be performed individually on virtual disk group members.

When replication commands are invoked on a virtual disk group, replication operations will only be performed on virtual disk group members that are configured in replications and in a state that allows the operation to be performed. These conditions may not apply to all virtual disks in the group.
Replication checkpoints cannot be sent to a group.

Enabling/Disabling Sequential Storage on Groups

Enabling and disabling sequential storage can be performed on the group or individually on members of a virtual disk group.

In order to enable the feature at the group level, all group members must be eligible for sequential storage and not have the feature already enabled; otherwise, members must be enabled individually. See Sequential Storage for eligibility requirements.
In order to disable the feature at the group level, all group members must be healthy and all affected servers must be running. Disabling sequential storage at the group level will disable the feature for all eligible members in the group and skip members that are already disabled.

Renaming Groups and Virtual Disks in Groups

Also see Rules for Naming SAN Components for size limitations.

Renaming Groups

Virtual disk groups, snapshot groups, and rollback groups can be renamed using either method:

From the DataCore Servers panel or Hosts panel, right-click on the object and select Rename. Enter the new name.
From the details page for the object, click Edit at the top of the page. Enter the new name and click Done.
Open the details page by clicking on the object in a panel.

Renaming Virtual Disks in Groups

Virtual disks that are members of virtual disk groups, snapshot groups or rollback groups can be renamed in one operation. All virtual disks that are members of the group will be renamed based on the root name provided. Numbers are appended to the root name when multiple virtual disks exist in the group.

This operation does not change the name of the group; only group members.
If the operation is performed from a virtual disk group, the operation will only be performed on virtual disks in the group, not members of subgroups.
To change the name of snapshots or rollbacks in a group, the operation must be invoked from the snapshot or rollback group.

To rename a group:

In the DataCore Servers panel, Host Panel or Virtual Disks list, right-click on the group to rename and select Rename Virtual Disks. A box will appear.
In the box, enter the new root name for the group.

Removing Virtual Disks from Groups

Virtual disks can be removed from virtual disk groups, snapshot groups and rollback groups.

When a virtual disk is removed from a virtual disk group, associated snapshots and rollbacks are removed from the subgroups and will be listed under the virtual disk that was removed from the group.
When a snapshot or rollback is removed from a snapshot or rollback group, the snapshot or rollback will be removed from the subgroup and will be listed under the source virtual disk in the group. The removed snapshot or rollback is no longer a part of the group, cannot have subsequent group actions performed on it and cannot be added back to the group.

In the DataCore Servers panel, Host Panel or Virtual Disks list, right-click on a virtual disk and select Remove from Group.

Deleting Groups

Virtual disk groups, snapshot groups, and rollback groups can be deleted.

When a virtual disk group is deleted, any snapshot groups or rollback groups in the virtual disk group will also be deleted. This operation will cause the permanent destruction of the associated snapshot and rollbacks in the virtual disk group. The virtual disks that are members of the virtual disk group are not deleted; they are only removed from the group.
Deleting snapshot groups and rollback groups will result in the permanent destruction of the associated snapshot and rollbacks in the group.

To delete a group:

In the DataCore Servers panel or any virtual disk list, right-click on a group and select Delete.
A confirmation message appears; read the message carefully. To continue with the operation, click the check box, then click Yes.

Viewing Group Details

Each virtual disk group has a details page with pertinent information for that group.

Group name and description can be changed at the top of the page by clicking Edit. When changes are made, click Done.

To open the details page for a virtual disk group:

In DataCore Servers panel or Hosts panel, expand Virtual Disks and click the group.
Alternatively, the details page can be opened from any Virtual Disks List. Double-click on a group in the list.
Information is organized under tabs (described below). Click on a tab to view the information. Additional fields may be available by selecting Column Chooser from the column header context menu in tabs.

When the Virtual Disk Group Details page is active, the Virtual Disk Group Actions tab appears in the Ribbon to perform actions on the group.

Virtual Disk Group Details Tabs
Info tab	Displays group information such as total allocated space and capacity (size) for all virtual disks in the group, number of rollback groups and snapshot groups in the virtual disk group, and the retention time, if CDP is enabled.
Virtual Disks tab	Lists all virtual disks in the group. Virtual disk information matches the information displayed in the Virtual Disks list. See Virtual Disks list for descriptions. Right-click a virtual disk in the list and a context menu appears to perform actions on the virtual disk. A link is provided to add virtual disks to the group.
Performance tab	Displays real-time performance measurements for the group. See Live Performance.
Events tab	Lists events for the group. Click an event in the list to view details in the Message Text area at the bottom of the tab. See Event Log and Alerts.
Snapshot Group Details Tabs
Info tab	Displays number of snapshots in the group, type (full or differential), current operation being performed and the snapshot point (timestamp of snapshot group).
Snapshots tab	Lists all snapshots that are members of the group. Snapshot information matches the information displayed in the Virtual Disks list. See Virtual Disks list for descriptions. Right-click a virtual disk in the list and a context menu appears to perform actions on the virtual disk.
Performance tab	Displays real-time performance measurements for the group. See Live Performance.
Events tab	Lists events for the group. Click an event in the list to view details in the Message Text area at the bottom of the tab. See Event Log and Alerts.
Rollback Group Details Tabs
Info tab	Displays the number of rollbacks in the group,type (persistent or expiring), current operation being performed, and the restore point (timestamp of the rollbacks in the group).
Rollbacks tab	Lists all rollbacks that are members of the group. Rollback information matches the information displayed in the Virtual Disks list. See Virtual Disks list for descriptions. Right-click a virtual disk in the list and a context menu appears to perform actions on the virtual disk.
Performance tab	Displays real-time performance measurements for the group. See Live Performance.
Events tab	Lists events for the group. Click an event in the list to view details in the Message Text area at the bottom of the tab. See Event Log and Alerts.