EMC VNX – Accessing Snapshot Data via CVFS

CVFS is checkpoint virtual file system. Remember? Within VNX SnapSure checkpoint = snapshot. CVFS is a navigation feature that provides NFS and CIFS clients with read-only access to online, mounted snapshots from within the PFS (production filesystem) namespace. This eliminates the need for administrator involvement in recovering point-in-time files. The snapshots are automatically mounted and able to be read by end users.

CVFS Naming Convention

There is a hidden directory, called .ckpt.  In addition to .ckpt_mountpoint entry at the root of the PFS, SnapSure also creates virtual links within each directory of the PFS. All of these hidden links are named by default .ckpt and can be accessed from within every directory, as well as the root, of a PFS. You can change the name of the virtual snapshot name from .ckpt to a name of your choosing by using a parameter in the slot_(x)/param file.

Default name of the snapshot is: yyyy_mm_dd_hh.mm.ss_<Data_Mover_timezone>, but that also can be change in param file.

Accessing Snapshot using Shadow Copy Clinet

CIFS clients can also access snapshot data via Shadow Copy Client.  This feature allows Windows users to access previous versions of a file via the Microsoft Volume Shadow Copy Server.

Previous Versions

Previous Versions

There is one risk though. Choosing snapshot on the window above and clicking ‘Restore’  you will restore snapshot on the production file system! But you can disable that button.. And it’s actually a really good idea to do so. Right before the restore there is a new snapshot taken, so you can ‘undo’ such a mistake. But it still can be messy if someone restore a snapshot, edit a file or two, and then discovery that he restored snapshot and he missess some files.

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