Snapshots

This page allows you to take, remove, and edit snapshots, as well as to configure snapshot schedule and retention settings.

Snapshots minimize disk consumption by preserving individual blocks rather than whole files. Extra space may be consumed when the files in shared folders or blocks in iSCSI LUNs are updated or removed.

Shared Folder

To take a snapshot for a shared folder:

Select the shared folder of which you wish to take a snapshot.
Note: You can press and hold Ctrl or Shift to select multiple items.
Click Snapshot > Take a Snapshot.
Enter the description in Description for the snapshot to be taken.
Tick/untick the Lock checkbox to determine whether the snapshot will ignore the retention settings when automatic removal is to be triggered.
Click OK to start taking a snapshot.

Note:

You cannot take snapshots if the available space of the volume is less than 100 MB.
Among the settings in Control Panel > Shared Folder > Edit, only the NFS permission will not be recorded in a snapshot.
Snapshot protects the data within recycle bin.

To make snapshot visible:

The folders and files in snapshots can be accessed via file services in #snapshot folders of the shared folder.

Select a shared folder of which you wish to make the snapshot visible.
Click Settings.
Go to the Advanced tab, and tick the Make snapshot visible checkbox.

Note:

Users do not have the write permission of any snapshot copies.
Users have the read permission of the snapshot copy only if, at the time when the snapshot is taken, their user accounts have been created and they have been granted the read permission of the shared folder.

To browse snapshots of a shared folder:

Select a shared folder of which you wish to browse the snapshots.
Click Snapshot > Snapshot List.
Select a snapshot you wish to browse, and click Browse.

Note:

Snapshots of encrypted shared folders cannot be browsed.

To remove snapshots of a shared folder:

Select a shared folder you wish to remove the snapshots of.
Click Snapshot > Snapshot List.
Select one or more snapshots you wish to remove, and click Remove.
Note: You can press and hold Ctrl or Shift to select multiple items.
You will see a confirmation message. Click Delete to confirm the removal. System will delete snapshots in the background. Deleting large quantity of snapshots may prolong the processing time.

Note:

If a shared folder is replicated, its latest snapshot synced to the destination server will be preserved and cannot be removed.
For better replication performance, several snapshots of the shared folder will be prevented from removal during the sync.
If you find that released space is less than expected when you delete snapshots, it might be because space reclamation is processing or because the space is still occupied by other snapshots, recycle bins, or file clones. To learn how much space you can free, please use the snapshot calculator.

To estimate storage usage by snapshots of a shared folder:

Select a shared folder you wish to evaluate snapshot usage of.
Click Snapshot > Calculate Size.
Select a time range by entering a start date and an end date, and then click Calculate now.
Note: The minimum time range is 7 days.

Note:

Only one shared folder can be estimated at a time.
The result is an estimation only. Actual snapshot usage depends on operations performed to the shared folder (e.g. snapshot restoration, data cloning, etc.).
If recycle bin is enabled in the shared folder, the deleted files will stay in the recycle bin and will not affect the size of the snapshots. However, if you delete the data that have taken been taken snapshots it will affect the size of the snapshots.

To view storage usage by snapshots of a shared folder:

After the estimation task is completed, click Task done to view the storage estimation report. Move the mouse cursor to view storage usage accumulation.

To clear a finished estimation task:

In Snapshots > Shared Folder, select a shared folder and click Clear to erase task details.

To edit snapshots of a shared folder:

Select a shared folder you wish to edit the snapshots of.
Click Snapshot > Snapshot List.
Select a snapshot you wish to edit, and click Edit.
You can modify the description of the snapshot in Description, and tick/untick the Lock checkbox to determine whether the snapshot will ignore the retention settings when automatic removal is to be triggered.
Click OK to save your settings.

To configure scheduled snapshots:

With scheduled snapshots, Snapshot Replication will automatically take snapshots at the pre-determined time and frequency, and it will thus lighten your workload to take snapshot manually.

Select a shared folder.
Note: You can press and hold Ctrl or Shift to select multiple items.
Click Settings.
In the Schedule tab, tick the Enable snapshot schedule checkbox, and set up the time and frequency to take snapshots. To cancel scheduled snapshots for this shared folder, please untick the checkbox.
Click OK to save your settings.
You will see a confirmation message. Click OK to confirm the configuration.

Note:

Scheduled snapshots' configuration will not be included in the Control Panel > Update & Restore > Configuration Backup feature.

To configure the retention settings for the scheduled snapshots:

Select a shared folder.
Note: You can press and hold Ctrl or Shift to select multiple items.
Click Settings.
Select Retention tab.
Specify how to retain and delete snapshots.
- Choose between these three options:
  - Always retain snapshots: When the maximum number of snapshots is reached, Snapshot Replication will stop taking new snapshots without removing the ones already taken.
  - Retain [number] latest snapshots: When the maximum number of snapshots is reached, the oldest snapshots will be overwritten by newly taken ones.
    Note: The number is subject to be different according to your Synology product model.
  - Advanced retention rules: You can configure retention rules for specified time ranges. Click Configure to edit the retention rule. For more information, please refer to the Retention Policy note.
- Choose when to delete snapshots: You can choose when to delete snapshots. We suggest setting the time to off-peak hours to reduce server load.
  - Set the time to a specific time of day, such as 08:00 or 15:00.
  - While taking snapshots: The old snapshots will be deleted when new snapshots are taken.
Click OK to save your settings.

To configure the snapshot naming policy:

Select a shared folder.
Note: You can press and hold Ctrl or Shift to select multiple items.
Click Settings.
Select Advanced tab.
Tick/untick the Use the time in the GMT +0 time zone to name the snapshots checkbox.
- If the checkbox is ticked, snapshots will be named after the Greenwich Mean Time (GMT) when they are taken. If your shared folder are accessed by users in different time zones or if your replication tasks are run across different time zones, it is recommended that you select this option to avoid misleading time information in snapshot names.
- If the checkbox is unticked, snapshots will be named after local time when they are taken. You can set the server's date and time in Control Panel > Regional Options.
Click OK to save your settings.

Note:

In older versions of Microsoft Windows, Windows File Explorer can only display Greenwich Mean Time (GMT) format in the Previous Versions tab. If you choose to name snapshots after local time, the snapshot names may show differently on DSM and Windows File Explorer, while this does not affect the snapshot operations.

iSCSI LUN

To take a snapshot for an iSCSI LUN:

Select the iSCSI LUN of which you wish to take a snapshot.
Note: You can press and hold Ctrl or Shift to select multiple items.
Click Snapshot > Take a Snapshot.
Enter the description in Description for the snapshot to be taken.
From the Lock drop-down list, select Yes/No to determine whether the snapshot will ignore the retention settings when automatic removal is to be triggered.
Click OK to start taking a snapshot.

To remove a snapshot of an iSCSI LUN:

Select an iSCSI LUN you wish to remove the snapshots of.
Click Snapshot > Snapshot List.
Select one or more snapshots you wish to remove, and click Remove.
Note: You can press and hold Ctrl or Shift to select multiple items.
You will see a confirmation message. Click Delete to confirm the removal. System will delete snapshots in the background. Deleting large quantity of snapshots may prolong the processing time.

Note:

If an iSCSI LUN is replicated, its latest snapshot synced to the destination server will be preserved and cannot be removed.
For better replication performance, several snapshots of the iSCSI LUN will be prevented from removal during the sync.
If you find that released space is less than expected when you delete snapshots, it might be because space reclamation is processing or because the space is still occupied by other snapshots, recycle bins, or file clones.

To edit a snapshot of an iSCSI LUN:

Select an iSCSI LUN you wish to edit the snapshots of.
Click Snapshot > Snapshot List.
Select a snapshot you wish to edit, and click Edit.
You can do any of the following to edit the snapshot:
- Change the description of the snapshot in Description.
- Select the Consistent state if application-consistent snapshot is enabled.
- Switch between Yes/No from the Lock drop-down list to determine whether the snapshot will ignore the retention settings when automatic removal is to be triggered.
Click OK to save your settings.

Note:

You cannot take snapshots of iSCSI LUNs when a volume has less than 1 GB of free space.
To apply the features of snapshot and replication to iSCSI LUNs, the iSCSI LUNs must be created as Standard iSCSI LUNs with storage acceleration or Advanced iSCSI LUNs.
iSCSI Manager is supported from DSM 6.2 onwards. Corresponding functions in previous DSM versions can be found at Storage Manager > iSCSI LUN.
In Snapshot Replication on your Synology NAS, you cannot take/edit/remove the snapshots of any iSCSI LUNs used by Cinder. For more information, please refer to DSM Help > iSCSI Manager > iSCSI LUN. For DSM versions earlier than DSM 6.2, please refer to DSM Help > Storage Manager > iSCSI LUN.
You are advised to install Synology Storage Console or Snapshot Manager to avoid possible data inconsistencies.
Upon completion of taking a snapshot or creating a replication task, if the status turns out to be Abnormal/Crashed, please delete the snapshot/replication and try again.
When you restore an iSCSI LUN to a snapshot version, you will lose all changes made to this iSCSI LUN after the time point when the snapshot was taken.
If the status of an iSCSI LUN changes to Unavailable, it means that some data-related errors occurred when the iSCSI LUN is accessed. The iSCSI LUN will be temporarily inaccessible to avoid severe data loss. Please contact Synology for support as soon as possible.

Terminologies:

Synology Storage Console: Synology Storage Console is a storage management plugin on VMware vSphere Client or Windows Server that simplifies managing and monitoring multiple Synology storage systems. It also allows you to take application-consistent snapshots directly from DSM.
- For VMware environments, the plugin is only compatible with VMware vCenter Server Appliance 6.5 U2 or above versions.
- You can download the plugin at Download Center and refer to Synology Storage Console for VMware and Synology Storage Console for Windows for more information.
Synology Snapshot Manager: Synology Snapshot Manager is a plugin that allows you to take application-consistent snapshots directly from DSM. After installing and activating Synology Snapshot Manager on Windows Server or VMware ESXi Server, you can click Registration List to see the registered clients.
- In the VMware environment, you need to install Synology Snapshot Manager on the Windows server where VMware vCenter Server has been installed. When a snapshot taking is triggered on DSM, VMware vCenter Server will be notified and flush all the data from memory to the iSCSI LUN on which the snapshot is taken to guarantee data consistency. Once the snapshot is complete, VMware vCenter Server will resume normal I/O operations of VMware datastore. Synology Snapshot Manager for VMware is supported on VMware vCenter Server 6.0 or previous versions.
- In the Windows environment, you need to install Synology Snapshot Manager on your Windows server. When a snapshot taking is triggered on DSM, Synology Snapshot Manager will leverage Microsoft Volume Shadow Copy Service (VSS) technology to generate consistent point-in-time copies of your data. Synology Snapshot Manager for Windows is supported on Windows Server 2008 R2, 2012, 2012 R2, and 2016.

To configure scheduled snapshots:

With scheduled snapshots, Snapshot Replication will automatically take snapshots at the pre-determined time and frequency, and it will thus lighten your workload to take snapshot manually.

Select an iSCSI LUN.
Note: You can press and hold Ctrl or Shift to select multiple items.
Click Settings.
In the Schedule tab, tick the Enable snapshot schedule checkbox, and set up the time and frequency to take snapshots. To cancel scheduled snapshots for this shared folder, please untick the checkbox.
Click OK to save your settings.

To configure the retention settings for the scheduled snapshots:

Select an iSCSI LUN.
Note: You can press and hold Ctrl or Shift to select multiple items.
Click Settings.
Select Retention tab.
Specify how to retain and delete snapshots.
- Choose between these three options:
  - Always retain snapshots: When the maximum number of snapshots is reached, Snapshot Replication will stop taking new snapshots without removing the ones already taken.
  - Retain [number] latest snapshots: When the maximum number of snapshots is reached, the oldest snapshots will be overwritten by newly taken ones.
    Note: The number is subject to be different according to your Synology product model.
  - Advanced retention rules: You can configure retention rules for specified time ranges. Click Configure to edit the retention rule. For more information, please refer to the Retention Policy note.
- Choose when to delete snapshots: You can choose when to delete snapshots. We suggest setting the time to off-peak hours to reduce server load.
  - Set the time to a specific time of day, such as 08:00 or 15:00.
  - While taking snapshots: The old snapshots will be deleted when new snapshots are taken.
Click OK to save your settings.
You will see a confirmation message. Click OK again to confirm the configuration.

To configure the consistent state of your iSCSI LUN snapshots:

Select an iSCSI LUN.
Note: You can press and hold Ctrl or Shift to select multiple items.
Click Settings.
Select Application tab.
Tick/untick Enable application-consistent snapshots checkbox to switch between the following consistent states:
- Application consistent: Snapshots in this consistent state can be taken only when Synology Snapshot Manager is installed on your Windows server or VMware vCenter Server depending on your operating environment to communicate with DSM. When application-consistent snapshots are triggered on DSM, applications will be notified, and flush all the data from memory to the iSCSI LUNs to be taken a snapshot of, hence the assurance of data consistency.
  Note: If Synology Snapshot Manager has not been installed on your operating environment, the application-consistent snapshot will remain disabled even if the checkbox is ticked.
- Crash consistent: If Synology Snapshot Manager has not been installed on any of your clients, you can only capture crash-consistent snapshots of iSCSI LUNs. When crash-consistent snapshots are triggered, applications will not be notified to flush the data from memory to the iSCSI LUNs, hence the inability to guarantee data consistency.
Click OK to save your settings.

Note:

Changing the consistent state settings will affect the equivalent settings in the Replication page.

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Retention Policy

This option provides an ideal solution to help you specify the maximum amounts of snapshot versions to save your volume space, but you may need to retain your snapshots for longer periods of time. There are a few things to note about Retention Policy:

Synology employs the GFS, or Grandfather-Father-Son retention policy. You can configure the maximum amounts of snapshot versions to be retained for the following time ranges respectively: hourly, daily, weekly, monthly, and yearly.
One snapshot can meet several retention rules at the same time. For example, one snapshot can meet the daily, weekly, and monthly rules.
The earliest snapshots will be retained if you take many snapshots within a certain period. For example, if you set a 10 weekly snapshots retention rule, and your snapshot schedule is set to take 1 snapshot a day, Snapshot Replication will retain the earliest snapshot of each week for the past 10 weeks.
If you have not taken snapshots for a certain period, the system will retain the most recent snapshots. For example, if the daily snapshot rule is set as 15 and there were not any snapshots taken in the past 30 days, the system will retain the snapshots taken 30 to 45 days ago.
All snapshot versions within one hour since the taking of newest snapshot will be kept by default, for your convenience to find and restore from recent snapshot versions. You can also lock a snapshot to prevent it from automatic removal by your retention rules.

Example 1:
If you want to keep daily snapshots for the past 3 months, weekly snapshots for the past 4 to 6 months, and monthly snapshots for the past 7 to 9 months, you need to input 0 for hourly snapshots, 90 for daily snapshots, 24 for weekly snapshots, 9 for monthly snapshots, and 0 for yearly snapshots.

Example 2:
If you want to keep hourly snapshots for the past 2 days, daily snapshots for the past week, weekly snapshots for the past month, and monthly snapshots for the past year, you need to input 48 for hourly snapshots, 7 for daily snapshots, 4 for weekly snapshots, 12 for monthly snapshots, and 0 for yearly snapshots.