Recover From Accidentally Deleted Files

Table of Contents

This guide will tell you how to copy a deleted file from a snapshot.

This guide will illustrate how to use Webdrive to find your deleted data and copy it back. You can use any of the other access methods, too.


What is a "Snapshot"?

A snapshot of a file system is a logical, point-in-time, read-only, copy of all files. It’s not really a complete copy. Instead, the file system keeps track of files that are changed or deleted after the snapshot was made. By definition, all snapshots are read-only, meaning you cannot delete a file from a snapshot. Restoring a file from a snapshot is as simple as copying the file back to your working directory/folder.

On CRSP, all snapshots are labelled by date and time. The timezone is GMT (Greenwich Mean Time). Snapshots are point-in-time copies of the CRSP file system. Snapshots are taken every 12 hours and retained for 7 days. Files that have been deleted more than 7 days ago are gone forever.

Is Snapshot a Backup?

Not really. Backups are generally thought of as historical copies of files and users could go to a backup to recover a file from many months ago. Snapshots provide some safety against the common "accidentally deleted" use case. CRSP does not keep historical backups of data. *Files that were deleted more than 7 days ago are gone forever.

Finding Snapshots

Due to the way the underlying filesystem (GPFS) is architected, you must first navigate to the "top level" of the CRSP file system and then navigate downwards to the correct snapshot folder to find your system.

This means that you will see all possible labs or home area folders (and there are 1000s of them on CRSP). Rest assured that only you and those you designate can see the appropriate files. All access permissions are fully enforced, even when navigating snapshots.

You can navigate in webdrive to the top-level by connecting the crsp-top-level share connection that is pre-defined by the UCI installation of webdrive. See Windows or Mac instructions.
You can also find the top level of CRSP while using the web browser interface to CRSP.

When you navigate to the CRSP top level, you will see a folder structure that is similar to the following:

Figure 1. CRSP Top Level.

Snapshots are held in the folders labeled LAB-SNAPSHOTS and HOME-SNAPSHOTS. If you click on [LAB-SNAPSHOTS], you will see a set of folders that are named after their creation date:

Figure 2. Timestamped Snapshots in the LAB-SNAPSHOTS folder

In this example, the most recent snapshot is @GMT-2019.5.13-19.00.1. It indicates that the snapshot was taken an May 13, 2019 at just after 7pm (GMT). This translates to 11am (PST). This folder contains that logical copy of all CRSP lab folders, as they were at that point in time. If you navigate into this directory, you will see ALL lab folders.

Figure 3. Labs that are part of a particular snapshot
When you navigate to your lab folder, you can find your missing file(s) and simply copy them to any writable folder. At that point, you have restored your deleted (or changed) files from the snapshot

Complete Deletion/Recovery Example

In this section, we illustrate a complete deletion and recovery example. We will use the ppapadop lab folder and we will focus on the file named FD12LITE. This file was created on April 18, 2019.

Deleting a particular file from a Lab folder

After hitting the "delete" key, the file now no longer exists in the writable folder. See figures below:

Figure 4. Folder before deletion of file FD12LITE
Figure 5. Folder after deletion of file FD12LITE

Navigate to the Snapshot copy of the file

In order to recover the file, you must navigate to the top level directory and then into the lab snapshots.

At this point, you want to select the folder that has a (backup) copy of your file. In this example, we are navigating to the @GMT-2019.5.13-19.00.1 folder. Please notice in the following screenshot that the path is LAB-SNAPSHOTS > @GMT-2019.5.13-19.00.1. This indicates that we are in a snapshot copy. We will continue to navigate into the correct subfolder that holds a copy of FDLITE12.

Figure 6. Navigate to lab folder

Copy file back to your working folder

At this point, you may copy the file in your usual manner per your host operating system (Windows) (Mac) (Linux). In this example we are going to copy it and put it back where it used to be.

Figure 7. Copy the file back to your working folder

That’s all there is to do. Once you have copied the file from the Snapshot, you have restored it!