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Chapter 8 Backup and Recovery
8.1 Snapshot – Fast Point-In-Time Copies
Snapshots are read-only copies of file-systems at a specific point in time. Snapshot
distinguishes itself in its speed. Creating a snapshot is not involved with copying user data,
thus usually taking less than a second.
The concept of snapshot is very different from tape backups. Data are not copied to any media
during backup. Instead, it just informs the NAS that all the data blocks in use should be
preserved, not being overwritten. That is why it can be so fast. The “copy” occurs during
everyday file access. When a file is modified after a snapshot is created, its original data
blocks are protected from being overwritten. The new updates are written to a new location.
The file-system maintains records and pointers to keep track of the snapshot data and file
changes.
1. Snapshot Management
To manage snapshots, please open the administration page.
Enter the “Backup → Snapshot → Manage” page and select a volume.