Snapshot Retention

Discussion created by sdpaiva Employee on Apr 8, 2013
Latest reply on Apr 24, 2013 by Ajay Singh

In a previous post, we touched on how Nimble’s efficient snapshots allow you to effectively protect your critical data, and we looked at recovery point objectives (RPO) specifically for vSphere across the customer base.


In this post, we’ll take a look at snapshots from a slightly different angle.  The number of snapshots that an array can handle is one metric you can look at to determine whether an array has efficient snapshot technology. However, that by itself is not enough - the other important metric to look at is retention.  Snapshots capture a point in time of a data set, such as a database. As data changes, each snapshot uses up some capacity to capture the changes since the previous snapshot.


Efficient snapshot technologies (such as Nimble’s) can use significantly less capacity than some older implementations in the industry (as much as 30x less capacity compared to some industry leaders). Such improvements in snapshot efficiency can allow for snapshots to be retained for sufficient time to form the basis of a reliable and cost effective data protection strategy.


Let’s take a look at the maximum length of time that snapshots are retained across the Nimble customer base (taken on April 4th 2013).



In this distribution, we can see that the vast majority of Nimble Storage customers retain their snapshots for several weeks or longer.  In fact, the distribution is fairly even once it gets over a period of 1 day.  Over 15% of Nimble volumes have a retention period of over 3 months, which means that these data sets can roll back to old data at multiple points in time, from over 3 months ago should the need arise.  This is significantly higher than typical retentions of snapshots on other primary storage architectures in the industry (which rarely exceed a week).


The numbers are even more significant because the Nimble install base is growing very rapidly (and a substantial fraction of the volumes in existence are relatively ‘young’). This real world deployment data validates that snapshots can be used as an efficient and cost effective way to protect data for weeks and months at a time.


Are you using snapshots as part of your data protection strategy?   If so, how long are you keeping your snapshots?