Snapshots and Snapshot Policies¶
Managing Snapshots and Snapshot Policies¶
Snapshots are Read-Only representations of the Volume’s data set at a given point-in-time. Snapshots are very efficiently thinly provisioned, sharing all the unmodified data chunks with the Volume. Write ordering is ensured at Snapshot creation, i.e. all writes that were acknowledged to the Server by the VPSA before the Snapshot was created will be contained in the Snapshot’s data set.
Manual creation and deletion of snapshots¶
To manually create a snapshot:
Go to the Volumes page, press the Data Services button and select Create Snapshot.
Enter a unique name for the snapshot and confirm the operation.
To manually delete a snapshot:
Go to the Volumes page, select the Volume and view the Snapshots South Panel tab to display the list of snapshots associated with this Volume.
Select the snapshot to be deleted in the Snapshots tab and press the Delete Snapshot button at the top left corner of the South Panel.
The snapshot will move to a Deleting state and will disappear from the list once the deletion process completes. Please note that Snapshots deletion typically takes less than a minute, but in complex configurations it may extend up to few minutes.
Note
You can not manually delete snapshots related to the volume mirrors. See Mirroring for details.
Managing Snapshot Policies¶
Snapshot policies define the Snapshots life cycle via the enforcement of creation and deletion policies. Snapshot Policies are “global” entities, and you can apply instances of the policies to one or more Volumes. Unapplied policies are idle—they do not consume any resources and never create any snapshots. A few points to consider:
You can apply a Snapshot policy to one or more Volumes.
You can apply multiple Snapshot Policies to a Volume.
If two or more Snapshot policies are scheduled to create a Snapshot at the same time on the same Volume, only a single Snapshot will be created. That Snapshot will only be deleted when all relevant Delete Policies approve its deletion.
Snapshot creation time is a “rounded” time, regardless of the precise policy creation time. For example, if you initialized a Snapshot Policy at 9:02 that has a Creation Policy to create a snapshot every 10 minutes, the Snapshots will be created at 9:10, 9:20, 9:30 and so forth (not at 9:12, 9:22, 9:32, etc.).
For the predefined snapshots policies like “Every Day” or “Every Hour” the Snapshot creation time is distributed on 10 minutes slots during the hour. The specified interval of one hour is kept, but not necessarily on the hour. Snapshots may be taken every hour 10 minutes after the hour, or 20 minutes after the hour, etc… (For example: 9:10, 10:10, 11:10 , …) If a precise snapshot creation time is needed, define a custom snapshot policy that specifies the exact time.
You can decide whether or not empty snapshots are to be created. i.e. if the time has come to create a Snapshot according to the Creation Policy but no data has changed since the previous Snapshot, you can specify whether a new and empty Snapshot will be created. This might be useful if you want to make sure the snapshot policy is enforced and snapshots are taken on time regardless of the data changes.
The following Snapshots Policies are predefined in the VPSA.
Name
Create Policy
Hourly Snapshots for a Day
Every hour
Daily Snapshots for a Week
Once per day after midnight
Weekly Snapshots for a Year
Every Sunday after midnight
Daily Backup for a Year
Once per day after midnight
Creating a new Snapshot Policy¶
Go to the Snapshot Polices page and press Create.
In the Create Snapshot Policy dialog, enter:
Name - Provide a meaningful name to the Policy.
Note
Objects names can be up to 128 chars long and can contain letters and digits, dashes “-” and underscores “_”
Creation Policy – Select the appropriate policy from the drop down list.
Deletion Policy – Use these 2 fields to define the maximum number of Snapshots to retain in the Deletion Policy. If you will be using this policy for Remote Mirroring, you can define a different number of Snapshots to retain on the DR site. This field is optional and defaults to the above deletion policy.
Allow Empty Snapshot Creation – Select this checkbox if you’d like Snapshots to be created according to the Creation Policy, even if no data was modified since the previous Snapshot.
Set as default policy for newly created volumes – Select this checkbox if you’d like all new Volumes to default to this Snapshot Policy. Select the appropriate Creation Policy from the drop down list.
Define the number of Snapshots to retain in the deletion policy.
Allows Empty Snapshot Creation – Set this checkbox if you’d like snapshots to be created according to the creation policy even if no data was modified since the previous snapshot.
If you will be using this policy for Remote Mirroring, you can define a different number of Snapshots to retain on the DR site. This field is optional and defaults to the above deletion policy.
Editing a Snapshot Policy¶
Go to the Snapshot Polices page, select the Policy and press Edit.
You can edit all of the Snapshot Policy’s attributes: Name, Creation Policy, Deletion Policy, Allow Empty Snapshots Creation and Set as Default Policy.
You can modify a Snapshot Policy even when it is active on one or more Volumes. The modifications in the Policy’s behavior will be reflected on all relevant Volumes.
If you reduce the number of Snapshots to retain for a Snapshot Policy that is active on one or more Volumes, it will trigger the deletion of all Snapshots that no longer meet the new Deletion Policy.
Applying a Snapshot Policy on a Volume¶
Go to the Volumes page, select the Volume and select Data Services > Attach Snapshot Policy.
In the Attach Snapshot Policy to Volume dialog, select the Snapshot Policy to apply to the selected Volume, and press Submit.
Detaching a Snapshot Policy from a Volume¶
Go to the Volumes page, select the Volume and press the Snapshot Policies south tab to view the Volume’s applied Snapshot Policies.
Select the Snapshot Policy to delete and press Detach Policy at the top left corner of the South Panel.
You will be prompted to decide whether or not to delete all the Volume’s Snapshots which are associated with this Policy.
Pausing or Resuming a Snapshot Policy¶
You can pause an active Volume Snapshot Policy. New Snapshots will not be created, but existing Snapshots are not affected. Pausing a Snapshot Policy on one Volume has no impact on other Volumes that also have this Policy active.
To pause a Snapshot Policy:
Go to the :Volumes page, select the Volume and press the Snapshot Policies tab on the South Panel to view the Volume’s active Snapshot Policies.
Select the Snapshot Policy and press Pause Policy at the top left corner of the South Panel.
The Policy Status will change to Paused.
To resume a Policy:
Note
The Pause / Resume button toggles according to the current Policy Status.
Select a Policy in a Paused state and press Resume Policy at the top left of the South Panel.
The Policy Status will change to Active.
Filtering Snapshots¶
Snapshots can be created manually, by using Snapshot Policies, by Remote Mirroring or by Backup to Object Store. This can result in many Snapshots spread across multiple Volumes.
Finding a specific snapshot could therefore take some time. The “Filter Snapshot” option will help you to find the snapshot you need more efficiently.
Go to The Volumes page, select a Volume and display the Snapshots tab in the South Panel.
Press the Filter button at the bottom of the page.
In the resulting dialog, define one or more of the following parameters:
You can define the From Date/Time and To Date/Time to filter only Snapshots that were created during that interval.
You can select the Origin of the Snapshot:
All – all Snapshots origins.
User – Snapshot created manually or via a Snapshot Policy which was attached to this Volume.
Mirror – Snapshots that were created by the Remote Mirroring application (using the Snapshot policy which was defined at the time of the Mirror creation).
Object Storage – Snapshots that were created by the Backup to Object Store (using the Snapshot policy that was defined at the time of the Backup definition).
Snapshot Policy – Select a Policy if you’d like to filter only Snapshots that were created by that specific Policy.