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You’ve heard of snapshot technology…

Most IT Data Storage professionals have heard about and have used snapshots at some point in their career. While there are a number of different and unique uses for snapshot technology, the basic use cases are a powerful and compelling addition to the data management portfolio.

Today we’ll review the most common use cases for snapshots using X-IO Technologies’ iglu enterprise storage system. The 3 major use cases are:

  1. Simple Data Recovery
  2. Application Consistent Recovery
  3. Replication and Disaster Recovery

Simple Data Recovery

In its simplest form, an iglu snapshot is a previous point in time view of a data image or file system kept separate from production disk data. Just as the name implies, it’s a picture of the way something looked when the “snapshot” was taken.

The most valuable use case for iglu snapshots is the ability to almost immediately recover and restore data without having to go to a traditional backup tape. This of course, is a huge time and energy saver. When it comes to recovering data, there are two important objectives to consider:

  • Recovery Time Objective (RTO): How long should it take to recover the data you need?
  • Recovery Effort Objective (REO): How much effort is required to actually recover the data you need?

The most obvious answers to these two questions are as fast and as easy as possible. Snapshots allow you to achieve this goal by decreasing recovery time from hours to minutes and reducing recovery effort to just a few mouse clicks. Snapshots have allowed organizations to move away from the time-consuming process of relying on backup tapes.

It’s important to consider the quantity and frequency of snapshots needed to provide the maximum amount of value to your user community. In most business environments, the general rule of thumb is fairly simple: the older the data, the less likely someone needs it. While generally true, some applications, like data mining, or historical business intelligence applications do not fit this rule. Therefore, there are diminishing returns on the value of a snapshot as the snapshot ages in general file system recovery use cases.

iglu blaze system allows for snapshotsX-IO’s iglu uses a very efficient snapshot technology with data block differential mapping so that entire file systems do not have to be cloned or copied to create the resulting snapshot view. Only the changed data is maintained for each snapshotted volume. This conserves valuable storage space while providing fast access to multiple versions of the same file system.

Even with point in time differential snapshot technology, it’s worth considering the snapshot schedule and the number of snapshots retained for potential use. The Recovery Point Objective (RPO) is the decision made by application stakeholders about how often and how far back in time the business needs to maintain a snapshot capability. With iglu snapshot technology, the granularity of the snapshot schedule can be set for individual volumes to match business requirements.

In general, the older the snapshot, the more space will be consumed to hold the differential data. Because every business is different, the best way to determine the actual space needed is to run trial snapshot schedules for a couple of weeks. You should also be aware of any cyclical business issues that might affect the levels of file system change, such as a tax preparation applications or seasonal product applications.

We typically see snapshot schedules that span from several days to weeks with an average of 20% of total capacity used to store the snapshots. Of course, each organization’s needs may vary. iglu snapshot technology allows for automatic overwrite of the oldest snapshots, creating a “rolling” snapshot schedule that can be enabled once suitable schedules are defined.

The simplicity of the Iglu snapshot technology allows schedules to be modified very quickly and easily to adapt to changing business needs.

Application Consistent Recovery

When a snapshot is taken at a particular time point where there is no application level or user level co-ordination the resulting snapshot is called a crash consistent snapshot. A simple crash consistent snapshot does not guarantee consistency when there are multiple volumes involved; nor will it capture uncommitted writes to disk that might be in flight at the time of the snapshot. There might be additional recovery steps needed when the snapshot volume is recovered, or there might even be lost data. To prevent this from happening, iglu snapshot technology has two powerful features that can be used, Snapshot Groups, and application-aware Snapshot Agents. Snapshot Groups allow multiple SAN volumes to have synchronized snapshots. This preserves application data that spans multiple volumes. Application-aware snapshots use host based agents that work hand in hand with IGLU and are used to quiesce application level write operations for a brief time so that iglu based snapshots can capture an application consistent image or view of the volume. There are iglu host agents for the most common host based applications, ie; VMWare, Oracle, SQL Server. Exchange, etc.

With iglu snapshot technology, it is simple to create snapshots at the same point in time across multiple volumes with host based agents that allow for complete and consistent application level recovery options.

Replication and Disaster Recovery

iglu snapshot technology can be used to provide efficient, cost effective data replication options. iglu Point-in-Time snapshot based replications remove disk latencies imposed by long distance synchronous transmissions. In addition, only the point-in-time net differential changes are transferred. These features conserve network bandwidth and improve overall write performance on replicated volumes.

Local replication schedules can be timed to trigger off of local snapshot schedules so that consistent file systems are maintained at both locations. When combined with Host-based application agents,  the remote site can maintain application consistent recovery options. This saves valuable time in a DR emergency as applications can be quickly brought back online.


With X-IO’s iglu enterprise storage system, organizations have the flexibility to set up snapshot schedules that integrate with a majority of host-based applications and allow organizations to determine the quantity, frequency and lifespan of a snapshot. Organizations can quickly and easily manage snapshot schedules and adjust schedules by volume as business needs change. It’s important to remember that snapshots are a time saving tool that augments disaster recovery, but do not replace the need for off-site backup or replication. iglu snapshots can be used to improve and simplify data replication tasks that provide quick and easy data and application recovery between sites.

I hope you enjoyed learning more about iglu’s unique and powerful snapshot features. Next time, we’ll explore iglu’s impressive Continuous Data Protection capabilities. CDP offers any “point-in-time” recovery options so that even the smallest write transaction can be protected and if necessary, recovered. Stay tuned!

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