Analyst webcast: Can snapshots replace backups?

In this short webcast, independent IT analyst George Crump of Storage Switzerland, presents “Can Snapshots Replace Backups”?


In it, he discusses the pros and cons of using snapshots for backups, and only mentions vendors during the Q&A.  So first, kudos to George for doing strictly educational webcasts vs. some of the thinly disguised infomercials we sometimes see.  I highly recommend this recorded event if you want to understand things to consider when someone suggests that you look at snapshots for data protection.


As a NetApp guy, I have to point out one of his slides entitled “Modernizing Snapshots”.  He discusses the major things to look for in snapshots.  I won’t try to steal all his thunder, but in essence, he’s saying that all snapshots are not created equal and we could not agree more.  Here are a few of his key points in bold text, and my comments on them as they relate to NetApp (but I still recommend checking out the webcast).


  1. Optimize snapshot method by using pointer based snapshots.  As he suggests, snapshots that use pointers vs. actual copies are faster and more space efficient.  With NetApp, a Snapshot copy is a point-in-time file system image. Low-overhead Snapshot copies are made possible by the unique features of the WAFL® (Write Anywhere File Layout) storage virtualization technology that is part of Data ONTAP®,  our Storage OS. Like a database, WAFL uses pointers to the actual data blocks on disk, but, unlike a database, WAFL does not rewrite existing blocks; it writes updated data to a new block and changes the pointer. A NetApp Snapshot copy simply manipulates block pointers.   So … fast and space efficient.
  2. Optimize snapshot method by implementing compression and  deduplication.  NetApp® data deduplication and data compression are fundamental components of our core Data ONTAP® OS. These innovative data reduction features can be used across multiple applications and storage tiers–including primary data, backup data, and archival data–to help you manage your data resources with greater efficiency.  Efficiency means saving you time and money.
  3. Integrate with other tools.  As most people know, our SnapVault and SnapMirror capabilities have been fully integrated with Data ONTAP for many years, and in the past few years, we and other backup vendors like CommVault, Symantec, and Syncsort have integrated our snapshot based solutions into their (your) backup solutions.  So you can enjoy the benefits of snapshots that George discusses, while continuing to use your favorite backup vendor.  Everyone wins.
  4. Replicate snapshots to local and DR sites.   In the diagram below, we show how customers combine our local and remote snapshots with our premier backup software, SnapProtect, to create a fully integrated, application and virtualization-aware data protection solution, all managed from a single pane of glass.

SoSo again, thanks to George Crump for asking the question “Can Snapshots Replace Backups?” and for his eloquent but concise answer on what to look for, to answer this question for yourself.



Why then only 255 snapshots are allowed if they are so cool?

because everything comes at a price and when going for too many snapshots your meta data and the needed housekeeping, calculating and searching will go out of hand.

jbahn Netapp Alumni

Lots of ways to work with the 255 snapshots  / volume limit.  Thousands of NetApp customers do it every day.  As George Crump points out, most people don't recommend that snaphots alone be used as a DP mechanism.  However, when combined with some kind of other backup, like snapshots to another FAS target using SnapVault, and/or tape or the cloud, snapshots do provide a great solution for applications that have low RTO and/or RPO requirements. Even for applications that have a longer RTO/RPO, snapshots allow Netapp customers to provide for things like self-service restore, rapid restore, etc.  And they really help with the problems of capacity growth and extended backup windows.

To speak to your point ... if you have 255 snaps per volume and only want to keep snapshots on primary storage for 14-30 days (like most customers), then you have the ability to snap 8-18 times a day or every 1.33 to 3 hours.  You could define a daily policy to SnapVault the hourlys to secondary storage, which would give you 255 days on secondary, in theory.  Of course, well before that, you'd probably move stuff off to tape or the cloud.  With our policy based management, you can set policies to retain snapshots for x number of days/jobs then age them off, creating more room for more snapshots / volume.

But as George points out, there are some compelling reasons to consider using snapshots for backup, if you ask the right questions and design the workflow properly.  And there are a LOT of people at vendors and the reseller community who can help.