Snapshots are one of the most powerful features of ZFS. A snapshot provides a read only point-in-time copy of a file system or volume. This copy does not consume extra space in the ZFS pool. The snapshot only records the differences between storage block references whenever the data is modified.
Taking snapshots requires the system have all pools, datasets, and zvols already configured.
A local replication creates a ZFS snapshot and saves it to another location on the same TrueNAS system using different pools, datasets, or zvols. This allows users with only one system to take quick data backups or snapshots of their data when they have only one system.
If you have only one pool, create a dataset in that pool to store the replication snapshots. You can use a zvol for this purpose. If configuring local replication on a system with more than one pool, create a dataset for the replicated snapshots on one of those pools.
Periodic snapshot tasks allow you to schedule creating read-only versions of pools and datasets at a given point in time. You can also access VMWare snapshot integration and TrueNAS storage snapshots from the Periodic Snapshot Tasks widget.
Use this procedure to create ZFS snapshots when using TrueNAS as a VMWare datastore.
You must have a paid edition of VMWare ESXi to use the TrueNAS VMWare Snapshots feature. ESXi free has a locked (read-only) API that prevents using TrueNAS VMWare Snapshots.
This tutorial uses ESXi version 8.
When creating a ZFS snapshot of the connected dataset, VMWare automatically takes a snapshot of any running virtual machines on the associated datastore. VMware snapshots can integrate VMware Tools, making it possible to quiesce VM snapshots, sync filesystems, take shadow copy snapshots, and more. Quiescing snapshots is the process of bringing VM data into a consistent state, suitable for creating automatic backups. Quiesced snapshots can be file-system consistent, where all pending data or file-system changes complete, or application consistent, where applications complete all tasks and flush buffers, prior to creating the snapshot.See Manage Snapshots from VMWare for more information.
File Explorer limits the number of snapshots Windows presents to users. If TrueNAS responds with more than the File Explorer limit, File Explorer shows no available snapshots. TrueNAS displays a dialog stating the dataset snapshot count has more snapshots than recommended and states performance or functionality might degrade.
There are two ways to view the list of snapshots:
Periodic snapshot tasks automatically create read-only copies of datasets or zvols on a schedule.
The Data Protection screen Periodic Snapshot Task widget displays periodic snapshot tasks created on the system. A periodic snapshot task allows scheduling the creation of read-only versions of pools and datasets at a given point in time.
Periodic snapshot tasks display the machine time, browser time, or both, depending on individual user timezone settings. Users can update timezone settings by utilizing the General Settings screen.
The Periodic Snapshot Task widget displays a list of tasks configured on the system. The widget shows a description of periodic snapshot tasks when a task is not configured.
TrueNAS snapshots capture the state of a dataset or zvol at a point in time, enabling data recovery without full backups.
The Snapshots screen lists dataset snapshots on the system. It allows you to add new or manage existing snapshots.
Access to the Snapshots screen is available using the Manage Snapshots link on the Data Protection widget on the Datasets screen and by clicking Snapshots on the Periodic Snapshot Tasks widget on the Data Protection screen.
If the selected dataset does not have snapshots, the screen displays No Snapshots are Available.
Use the VMware Snapshot Integration option on the Data Protection > Periodic Snapshot Tasks widget to create snapshots when you are using TrueNAS as a VMWare datastore. See Creating VMWare Snapshots for a detailed tutorial.
VMware Snapshot Integration opens the VMWare Snapshots screen.
Add opens the Add VMware Snapshot screen.
| Setting | Description |
|---|---|
| Hostname | Enter the IP address or host name of the VMWare host. When clustering, enter the vCenter server for the cluster. |
| Username | Enter the user on the VMWare host with permission to snapshot virtual machines. |
| Password | Enter the password associated with the user entered in Username. |
| Datastore | Select a VMFS datastore to synchronize with the host from the dropdown list of options. Click Fetch DataStores to populate this list with options from the VMWare host. You must click Fetch Datastores before you click in this field or the creation process fails. Selecting a datastore also selects any mapped datasets. |
| ZFS Filesystem | Select a TrueNAS ZFS dataset from the dropdown list of options. This field does not populate until you click Fetch Datastores. You must click Fetch Datastores before clicking in this field or the creation process fails. |
Click Fetch DataStores to connect TrueNAS to the VMWare host. This synchronizes TrueNAS with the VMWare host and populates the ZFS Filesystem and Datastore dropdown lists with the information from TrueNAS and the VMWare host response.
