Opting for the Right Snapshot Method

By CIOReview | Tuesday, January 17, 2017
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Snapshot technology is fast becoming a popular and preferred choice for data protection and other important tasks, such as data cloning, data replication, and data mining. In industry parlance, the snapshot can be defined as a process that has the ability to record the state of a storage device at any given moment in time. It is also used to reduce recovery time and efficient backup of data in case of any calamity. However, one should be careful in selecting a solution according to the storage needs of an organization. IT professionals are increasingly counting on snapshots to provide protection in the virtual environment.

The best part of snapshot is that it creates a copy of data at a certain point in time. A snapshot copy doesn’t interfere with the original copy and it is always available for the general applications. The main use of snapshots is in the storage arena, which were initially created to solve data backup problems and backing up large volumes of data. To manage all the snapshots, snapshot manager software is required, which initiates the snapshot, manages the copies of data and keeps them updated and secure. There are various types of snapshots and some of them are listed below:

• Application Snapshots: Some of the applications have the ability to create and manage snapshots of the data that they create. One of the advantages of an application snapshot is that they can be managed easily and the replicated data can be redirected to any secondary storage device. This reduces the cost to a great extent.

• File Snapshots: It has become a growing trend among organizations to build snapshot capabilities into file systems. This snapshot method is similar to application snapshots but it take into account and works on the whole file system instead of just an application, and it can be managed manually.

• Storage Snapshots: This is the most general and widely used snapshot and it is driven by hardware. There are distinct advantages of this method. Firstly, they can be managed efficiently as there are lesser snapshots to manage, and secondly, snapshots can be maintained without significantly altering the process.

Various vendors offer different techniques for implementation of snapshots and they have their own benefits as well as drawbacks. Some of the techniques are listed below:

• Copy-on-Write or Shadowing: When a snapshot is created in the first place, the original data is stored and kept as a backup. But the fact remains that there is no physical copy of the snapshot that is created at a specific moment in time. The data is copied and kept into the storage array as a snapshot copy. The original data is then written over it and is called “copy-on-write” technique.

• Redirect-on-Write: It can be termed as a replica of the copy-on-write technique. In this technique, a new location is allotted for snapshots as new writes are directed there. The main advantage of this technique is that only one write takes place at a time, which is different to copy-on-write, where two writes can occur at a time—one is for writing data on an original copy and the other one is for the changed data copy.

• Continuous protection of data: This is the most common and popular process offered by vendors for storing snapshots. It offers a continuous data protection with continuous backup, which is updated according to the changes. The change is captured automatically and is stored at a separate location.

With these options available to choose from, it becomes imperative to take into account the storage and backup requirements and plan accordingly to implement the best suited snapshot method. Many organizations opt for multiple snapshot methods and it’s like an amalgamation of various methods working in perfect harmony. For small organizations, an application snapshot is the most favored method, while larger organizations opt for storage snapshots.