NetApp Virtual Storage Console Default Provisioning and Cloning Settings

As a VMware administrator, if you aren’t using Virtual Storage Console (it’s free!) to assist with administering your NetApp storage, you’re missing out on a great tool. It simplifies a lot of tasks through abstraction and a GUI. That being said, I know not everyone has that advantage, especially if you work for an organization where silos are still alive and well.

In order to facilitate best practices when it comes to creating datastores, whether FC/iSCSI LUNs or NFS, I want to publish the settings that VSC uses to create the volumes. As a VMware administrator, you can approach the storage team and ensure the volumes/LUNs/etc. are configured in this manner, or as the storage administrator this is the baseline for VSC configures them.

Remember that these are best practices / recommendations only. They ALWAYS come with the “it depends” caveat…every setup is different, so not all of these may be appropriate for you and your environment.

All of these settings are documented in the VSC Installation and Administration Guide. Additionally, justification and rationale can be found in TR-3749 and TR-4068, the two best practices guides for using vSphere and NetApp together.

A side note: All of the settings below are controlled in the VSC preferences file ([VSC_home]\etc\kamino\kaminoprefs.xml). If you want to change the default behavior of VSC, that is the place to do it.

Volume Settings

Fractional Reserve
Fractional reserve, which is the percentage of a LUN to reserve when taking a snapshot of the containing volume, defaults to 0 when using VSC (the system default is 100). To change the setting from the command line:

Access Time Updates (no_atime_update)
By default, the volume will update metadata on file access to reflect when the file was last accessed. This has little value in a VMware environment, but adds IOPS for the metadata updates. For maximum performance, VSC sets the volume option “no_atime_update” to on.

Deduplication / Efficiency
Deduplication is enabled by default for VSC created volumes. I won’t address it in detail here, but there are other settings that should be considered when configuring deduplicaion on your volumes, such as scheduling and compression. Scheduling in particular is important…make sure you don’t overlap with other major operations (such as backups) which can affect both task’s completion time.

Snap Reserve
Snap reserve is the amount of space (in percentage) of a volume to reserve for snapshot writes. This space is removed from the available capacity of a volume…for example, a 100GB volume with 10% snap reserve will show as having 90GB available. VSC sets the snap reserve to 0% so that volumes will show as their true size. The downside to this is that space consumed by snapshots (snapshot size is the amount of existing data that has changed since the snap was taken) is seen as additional consumed space in the volume.

This can be both good and bad. Good because you always want to know exactly how much space you have available, bad because deleting a VM will not result in the space being returned to the available capacity of the volume until the snapshot is deleted. This can be confusing if you have a volume which is running out of space, you delete/remove some VMs, but the space is not immediately available in the volume.

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