VSI 7.1 eNAS compression/deduplication

VSI 7.1 is now available for download and while not a blockbuster on the VMAX front since we had ours with the 7.0 version, there are a couple minor updates and one new feature. Let’s start with the minor changes.

The first is that 7.1 adds support for the vSphere 6.5 Web Client. (vSphere 6.5 does offer a semi-functional HTML 5 client but we do not support that yet; but HTML 5 is coming to VSI.). Note that I said support for the Web Client and not vSphere 6.5 in general. That’s because we do not support any of the new features of 6.5. Specifically VMFS 6 and NFS 4.1 datastores come to mind. All datastores in vSphere 6.5 will still be VMFS 5 and NFS 3. Be aware that VMware does not offer upgrade ability from VMFS 5 to 6 (or NFS 3 to 4.1 for that matter) so if you want VMFS 6 you cannot use VSI. One task in VSI that can be used with VMFS 6 is reclaim. This is because when VSI runs the task it does not check the VMFS version and the CLI command is the same for all VMFS datastores (BTW we no longer require root access). Of course VMFS 6 now offers automated UNMAP by default so manual reclaim may be unnecessary. You also might see some functionality working – like datastore detail for VMFS 6 in certain views – but most tabs (e.g. EMC VMAX Datastore/LUN Viewers) will not return information and in any case it isn’t supported.

The second minor update is a new column in the create datastore wizard which will tell the user if the storage group is compressed. This is only pertinent to VMAX All Flash. Here is a screenshot:

datastore_compression_columnThe one new feature for VMAX is compression/deduplication with eNAS. Before the VMAX All Flash offered compression, our eNAS feature let you enable compression and deduplication on NFS or CIFS. On eNAS (as on VNX) these features are part and parcel – once activated both features are enabled. Compression and deduplication can offer great benefit to VMs on eNAS by reducing the storage footprint by as much as 50%, with only minimal CPU impact on the array. Normally turning it on or off is done in Unisphere via a simple radio button.

When activated, eNAS will begin both compression and deduplication across all files on the system.

VSI 7.1 now will offer the ability to enable/disable file compression/deduplication on eNAS. The implementation of compression/deduplication on eNAS is actually the same as VNX in the initial release. What this means is that enabling the feature does not actually turn it on continually, rather the state is changed from Off to Suspended. This has 2 effects. First, an initial compression process is run against the file system (impacting all VMs), reducing the storage footprint. Second, the file system is scanned by the deduplication process to gather statistics, but the actual deduplication process is not executed. This is all by design. A suspended state still permits deduplication to be run through the DHSM API, allowing more specific targeting of files. Compression can also be re-executed by re-running the VSI menu option. So it is important to remember that VSI will not leave compression/deduplication in an active state. If an active state is desired, Unisphere should be used to turn compression/deduplication on as shown in the previous image.

In order to use the compression/deduplication capability, there is an extra requirement when setting up the eNAS adapter instance. In VSI 7.1 a new checkbox called “Register access to file compression” requires that Distributed Hierarchical Storage Management (DHSM), or FileMover, is setup along with a user and password for that feature. I was going to cover the setup here but I asked that it be added to the VSI Product Guide so you will find it there (link at bottom). It’s a quick set of steps that is run from the CLI on the Control Station. Here is the dialog when adding the eNAS adapter instance where you supply the information. If you do not setup DHSM, you will not be able to use compression/deduplication.


The new menu is available at both the datastore level and VM level. When right-clicking on a datastore, the menu is present. Note the Extend VVOL Datastore option is for VNX only.


VSI will only display the compress/deduplication option when a datastore is NFS. Similarly, the menu is available at the VM level only when the VM is on an NFS datastore. If the VM is located on both NFS and VMFS, the menu will only appear if the config files (and typically Hard Disk 1) are on NFS.


Once executed, VSI will not provide a response; however multiple tasks will appear in the vCenter that can be monitored. Note that an initial run can take some time to complete depending on the size of the used storage, in this case about 8 1/2 minutes.


During the initial compression/deduplication, the file system will expand. Here we can see the original size in the red box is about 36 GB, or the size of the VM, but in the blue box notice the size has expanded to 48 GB.


If we look at the properties of the NFS in Unisphere after the vCenter tasks complete, the blue box now shows a size 7 GB smaller than the original size. As I also mentioned, the deduplication statistics have been collected but the process not executed.

post_compressI do want to make clear what to expect if you turn off compression/deduplication though VSI. Turning it off will re-inflate everything it compressed/deduplicated. Now similar to the initial compression, decompression will also expand the file system. See how after I turned off the feature, the size immediately begins increasing. That’s why it is very important to be sure you have the free space available for both enabling and disabling the feature.

So that’s the extent of the feature. One feature that has yet to be ported to eNAS is fast cloning statistics. As such this message will be displayed when viewing a VM.


Some caveats to be aware of with compression/deduplication:

  • If you run enable multiple times in a short period the vCenter tasks may fail. This is expected.
  • The VSI menu does not impact the default settings of compression/deduplication. Here is an example.


  • Under the storage device properties that VSI displays, there is no row that shows the current state of compression/deduplication. You must check Unisphere (or use CLI). This will be rectified in the next release.
  • The only way to deduplicate files is to use the DHSM API or to set the status to On in Unisphere. The VSI functionality will not do it.

As I noted, eNAS has the same functionality as VNX. In the next release of VSI, however, the behavior for eNAS will change. There will only be a single menu option available at the datastore level for enabling compression/deduplication and when it is run the state will be set to On, meaning from that point forward compression and deduplication will be handled by the array. This behavior is far more practical for most customers. Of course if a state of Suspended is preferable, again Unisphere can be used.

You can find the latest release and documentation here. Note that 7.1 now officially supports the HYPERMAX OS 2016 Q4 SR:

VSI for Web Client



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