# Archive Backup

Navigation: Working with Nx Witness > Configuring Server Settings > # Archive Backup |

Some disks on a server can be designated as backup storage. They will store a copy of the archives recorded to the main storage on the same server.

Note: Only archives from main storage of a given server will be backed up. If there is archive on some other server you want to backup, you should configure backup storage for that server as well.

Backup can be set up in two ways – on demand or realtime. On demand backup is activated either by command or according to a schedule, and will copy all existing archive from main storage to backup.

| - Client - Server - Archive Index database - Storage disk - Backup storage

Because large amounts of data are being copied during backup, it is possible to set bandwidth limitations or to schedule regular backups at specific times, to minimize the negative impact of loading the network. On demand backup continues until all data on the main storage is backed up, and may take significant time, especially if many cameras are being recorded to the main storage.

If on demand backup fails at some point or is canceled, the archive already backed up remains on the backup storage. Just the remaining part of the archive will be backed if the backup process is restarted.

With realtime backup, only live streams that are being received from active cameras will be recorded to the backup storage. Archive that already exists on the main storage will not be backed up.

Outdated archive is deleted from backup drives in the same way as from main ones, but independently of the main storage. In other words, if the backup storage has higher capacity, the maximum archive age on it will also be greater.

The opposite is also true – if backup storage is smaller, archive age will be less.

In order to save storage space, a System can be configured to backup only archive from certain cameras or only certain streams. Camera recording is backed up only if the camera is selected in backup settings and backup storage is configured on the server that camera is currently connected to.