• June 30, 2022

Rocket Storage Monthly: TimeFinder–Three Ways to Backup with an EMC VMAX Array


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EMC is one of the biggest companies in the business of enterprise storage ,and as such you’ll find that their products are used by many companies globally. If you’ve worked with EMC’s Tier 1 VMAX arrays, you might have noticed that they’re equipped with a variety of backup options. But which is best for your environment?

TimeFinder
Image via www.EMC.com

If you’re not familiar with EMC’s storage products, the VMAX arrays are the most recent models from a line of systems known as Symmetrix. Something the VMAX models 10K, 20K, and 40K all have in common is the Enginuity OS, which enables the TimeFinder family of backup methods, which provides different types of backups to suit the needs of any applications. You’ll find that some TimeFinder features are also present in previous Symmetrix models, but we’ll be focusing on the VMAX for now.

The TimeFinder family of backups currently includes TimeFinder/Clone, TimeFinder/Snap, and TimeFinder/VP Snap. For all types of TimeFinder, a backup will always be created by way of a pairing between Source and Target volumes in a one-to-one relationship. The Source Volume is defined as the original volume which contains the data that you want to backup, while the Target Volume contains the backup data. Let’s look at each type of backup.

TimeFinder/Clone

  • When using Clone, the Source and Target volumes must can be Standard (using RAID), BCV, or thin provisioned (TDEV) devices. This backup type is a good choice for creating high performance copies. Clone gives you two different options for backups: Either a full copy or a time-saving “Nocopy”.
    • Full Copy: This can be good choice if you want to have a complete copy of your data on a separate set of disks. Full copy will be the most time-consuming method, but the option to make differential copies using previous full copy backups reduce the time needed for subsequent backups.
    • Nocopy: With this option, initially backup data is visible to hosts from the Target using pointers to the data on the Source. Depending on TimeFinder configuration, Nocopy will copy data to the Target Volume over time, under one of two circumstances: Either when the data is accessed or when a write operation occurs.

 

TimeFinder/Snap

  • Snap provides space-efficient snapshots of Standard volumes. With Snap, the Target Volume is a virtual device (VDEV) that is created from a virtual device (SAVE) pool. Unlike a full copy, the snapshot only consumes as much data as was written after the snapshot was created. Similar to TimeFinder/Clone’s Nocopy, all data is accessible from the Target at the moment after snapshot creation via pointers to the Source’s data.
  • When a track is changed, the original data is relocated to the pool. A single Source can have as many as 128 active snapshot sessions, so Snap is geared towards being a good space-efficient solution for keeping multiple point-in-time snapshots. However, the downside to snapshots is that for tracks pointing to the Source, read operations will access the production volume and as a result there can be a performance impact under heavy utilization.

 

TimeFinder/VP Snap

  • VP Snap is a snapshot solution where both the Source and Target volumes are TDEVs. VP Snap is a very space efficient way to have multiple point-in-time snapshots, as not only does the thin-provisioned nature of TDEVs keep used space to a minimum, but VP Snap snapshots are copy-on-write just as TimeFinder/Snap snapshots are.
  • When a Source track has been modified, only a single copy of the track will be moved to the thin pool to be shared by all of the Source’s Targets. The Targets for a source may reside in the same Thin Pool as the Source, or in a separate pool although all Targets must be located in the same pool.  If your environment calls for numerous point-in-time snapshots, you’ll certainly benefit from this space-saving technique.

Ultimately, the best backup configuration for your application may be a combination of more than one type of TimeFinder backup. A single source can have multiple types of backups at once, and some configurations even allow for target volumes themselves to be a source to another tier of backup targets.

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