User Guide

Basic Snapshot Concepts
The ReadyNAS can provide protection of shared folders and LUNs through snapshots. Snapshots contain
references to data on a shared folder or LUN. They take no space until the data they reference is changed
or deleted. Strictly speaking, snapshots are not backups, but they function as backups because you can
recover data from snapshots.
You can take snapshots only of shared folders or LUNs.You cannot take a snapshot of a volume. Snapshots
reside on the same volume as the shared folder or LUN from which they were created.
The ReadyNAS can automatically take snapshots of a shared folder or LUN according to a schedule that
you specify.You can also manually take or delete individual snapshots at any time. Depending on available
storage space, you can keep an unlimited number of snapshots.
WARNING:
When the available storage space on a volume decreases below a threshold (set
to a default of 5 percent) of the volume’s total storage space, the oldest automatic
snapshots are automatically deleted to bring the available storage space back to
the threshold or higher. Manual snapshots are never automatically deleted.The
threshold is part of the snapshot settings for a volume.
Once protection is available, the shared folders and LUNs on the Shares page indicate the number of
snapshots and the number of days with protection.
Figure 9. Shared folder with daily snapshots
For snapshots to be accessible to users from their network-attached device you must
select the Allow snapshot access check box in the shared folder or LUN settings window.
For more information, see View and Change the Properties of a Shared Folder on page
52.
Note
Hourly snapshots are not taken for spun-down disks, but daily snapshots are taken.Note
Smart Snapshot Management
ReadyNAS OS 6.1 and later uses Smart Snapshot Management to reduce the number of automatic
(continuous) snapshots per shared folder or LUN. Every hour, this feature automatically prunes older hourly,
daily, and weekly snapshots, according to the following rules:
Snapshots
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ReadyNAS OS 6.7