Nimble Snapshots

When you take a snapshot of a volume or LUN it provides a point in time copy of the data by copying the metadata, almost instantaneously.

Traditionally when taking a snapshot at storage level the metadata is copied and then any subsequent writes are done at the same time as copying the changed block to a fixed location, usually designed to hold snapshot data. This implementation is known as Copy On Write (COW) and while it provides optimisation for reading data; writes could take a performance hit.

Nimble snapshots use Redirect On Write (ROW) by copying the metadata when a snapshot is taken, but then redirecting the write to a new free location on the array. None of the original data is copied like it is with the COW implementation. Nimble also uses a built in sweeping process to continually consolidate previously used blocks by creating full RAID stripes of free space, which allows it to maintain consistent read and write performance.

Nimble snapshots are configured in the web GUI for the array, there is no additional licensing cost. After logging in to the Nimble you will see the snapshot usage figure on the home page.

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One of the primary advantages of storage based snapshots is that they eliminate traditional backup windows. By instantly snapshotting the volume or LUN we have an immediate recovery point stored on the same physical array as primary data, without impacting the end application. Furthermore by only capturing changed data, we can take snapshots more frequently and improve recovery point objectives.

Snapshots integrate well with Zero Copy Cloning; a key Nimble feature which eliminates the storage footprint of repetitive data along with inline deduplication and customisable block sizes. This allows for quick cloning of the snapshot into a writeable volume which can be mounted elsewhere, such as VDI or development environments where multiple copies of a master data set are required, without the storage overhead.

Manual or automatic snapshots can be configured on a per volume basis from the Manage > Volumes page, double click the volume you want to snapshot. To take a manual snapshot click Take Snapshot. To configure automatic protection click Edit and select the Protection tab. Configure the schedule as appropriate.

To manage snapshots click the Snapshot tab, here you can delete, clone and restore snapshots. It is possible to create and mount a clone of a snapshot using PowerShell, you’ll find some useful info here to get you started.

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