Prior to version 1.1.6 the appliance's root filesystem was essentially confined to a given appliance, once and for all. Not anymore! There's a new functionality that was also dubbed a traveling Operating System, that makes it possible to move the appliance's root filesystem from appliance to appliance and back, clone it locally and remotely, copy it between appliances' system volumes and data volumes, and, last but not the least - synchronize and replicate system configuration. In fact, the remote host does not necessarily needs to be another NexentaStor appliance. This may be any ZFS based system, or even any non-ZFS system storing system configuration files in their expected (relative to root) locations.

This new functionality addresses the following use cases:

• cloning appliance's root filesystem, using as the source a given (master) appliance
• restoring appliance's system in the case of catastrophic failure (assuming that its root filesystem was previously saved and that the appliance is freshly installed with NexentaStor release 1.1.6 or later)
• synchronizing system configuration with a given appliance (sometimes also called “gold master”)
• storing appliance's configuration and uploading to an unconfigured appliance, to restore the latter to a known state.

There is no limit on the number of root filesystem clones, each of which can be snapshoted to preserve its content from write access, etc. This may help in a variety of disaster recovery scenarios.

There are two principal ways to restore a root filesystem:

1. clone an existing root filesystem, which may be local or remote
2. copy differences (delta) from an existing root filesystem, which again may be local or remote, residing on another host, which may not necessarily be NexentaStor appliance.

Cloning of an existing root filesystem results (as the name implies) in exact clone of the original rootfs. If the original (source) rootfs does not already reside on the appliance's system volume, it will be first transported over from its source location using NexentaStor auto-sync mechanism. It will then be converted in-place into a new bootable root filesystem.

The second principal way - copying differences (or delta) - implies having two root filesystems of the same NexentaStor release^(*) that you'd like to synchronize, as far as the system configuration is concerned. Note that if you are copying the delta from remote location onto your local appliance, the current active root filesystem is left intact. The System Restore Wizard will first, clone the current rootfs and second, perform the copying of differences into this new cloned location.

To start using this functionality, simply type:

nmc$ setup appliance checkpoint restore

Note: for defintion of the "system checkpoint" (or simply, "checkpoint"), please refer to the following F.A.Q. article:

• What is a "system checkpoint"?

To create a local or remote clone of the appliance's root filesystem, type

nmc$ create auto-sync

and select 'rootfs' when prompted to choose replication source.

As always, option -h (help) with any of these commands will show detailed manual page and examples.

See also:

• How can I use NexentaStor to backup/archive/restore/replicate/recover my data?
• What is the difference between 'auto-sync' and 'auto-tier' storage services?
• I would like to backup not only my data but snapshots as well, please advise..
• What is a "system checkpoint"?
• What's new in auto-sync replication?
• Auto-sync User Guide (PDF).
• Auto-sync in Reverse (PDF)

^(*) The restriction that is not enforced at the time of this writing, albeit recommended.