To Snapshot Or Not To Snapshot? That Is The Question When Leveraging VNX Unified File Systems

For those of you who are leveraging VNX Unified File systems, were you aware that you have the ability to checkpoint your file systems?

If you don’t know what checkpoints are, checkpoints are a point-in-time copy of your file system. The VNX gives you the ability to automate the checkpoint process. Checkpoints can run every hour, or any designated length of time, plus keep those files for whatever length of time is necessary (assuming of course that your data center has enough space available in the file system).

Checkpoints by default are read-only and are used to revert files, directories and/or the entire file system to a single point in time.  However, you can create writable checkpoints which allow you to snap an FS, export it, and test actual production data without affecting front-end production. 

VNX Checkpoint also leverages Microsoft VSS: allowing users to restore their files to previous points created by the VNX. With this integration you can allow users to restore their own files and avoid the usual calls from users who have accidently corrupted or deleted their files.  Yet, there are some concerns as to how big snapshots can get. VNX will dynamically increase the checkpoints based on how long you need them and how many you take on a daily basis. Typically the most a snapshot will take is 20% of the file system size and even that percentage is based on how much data you have and how frequently the data changes.

For file systems that are larger than 16TB, accruing successful backup can be a difficult task. With NDMP (network data management protocol) integration you are able to backup the checkpoints and store just the changes instead of the entire file system.

Take note that replicating file systems with other VNX arrays will carry your checkpoints over, giving you an off-site copy of the checkpoint made to the production FS. Backups on larger file systems can become an extremely difficult and time consuming job – by leveraging VNC Replicator and checkpoints you gain the ability to manage the availability of your data from any point in time you choose.

Photo Credit: Irargerich