Hands-on with VNXe 3300 Part 5: Storage provisioning


When provisioning storage on VNXe there are many options depending on the host type: Microsoft Exchange, Shared folders, Generic iSCSI, VMware or Hyper-V . Because this VNXe is only going to serve VMware ESXi hosts I’m going to concentrate on that part. I will go through provisioning storage from VNXe and also using VSI Unified Storage Management Plug-in.

Hands-on with VNXe 3300 series [list updated 9/23/2011]:

  1. Initial setup and configuration
  2. iSCSI and NFS servers
  3. Software update
  4. Storage pools
  5. Storage provisioning
  6. VNXe performance
  7. Wrap up

iSCSI datastore

In the last part a storage pool was created. The next step is to create datastores on it and provision those to the hosts. There are two options when provisioning datastores for VMware from VNXe: VMware datastore or generic iSCSI. When using the VMware storage VNXe will automatically configure the iSCSI targets to selected ESX hosts and also create the VMFS datastore. If generic iSCSI is created then all those steps have to be done manually to each ESX. I really recommend using the VMware storage from these two options. VMware storage can be created from Storage – VMware storage.

At this point only iSCSI server was configured so the only option was to create a VMFS datastore.

The next step is to select the iSCSI server and the size for the datastore. When creating the first datastore it really doesn’t matter which iSCSI server is selected. If the iSCSI_A (on SP A) server is selected for the first datastore then iSCSI_B (on SP B) should be selected for the second datastore to balance the load on the SP’s. When selecting the iSCSI server on SP A this means that all the datastore I/O will go through the SP A. If all the datastores are placed on one SP there could be a situation where the whole VNXe performance is impacted because all I/O goes through that SP and the other SP is idle. So it is important to balance the datastores between SPs. VNXe is not doing this automatically so the user has to manually do this when creating datastores. If datastores are distributed between the SPs and the other SP fails all the datastores on the failed SP’s iSCSI server are moved to the other SP. When the failed SP comes back online all the datastores originally located on it are moved back.

There is an option to configure protection for the storage. Because this datastore is only for testing I chose not to configure the protection.

Step 5 is to select the hosts that the datastore will be attached to. Datastore can be connected to a specific iSCSI initiator on ESX server by expanding the host and selecting Datastore access for the specific IQN. If Datastore access is selected from the host level then the VNXe targets are added to all iSCSI initiators on ESX.

After these steps are completed VNXe starts creating the datastore, adding iSCSI targets to the selected ESX hosts and iSCSI initiators on those and finally mounts and creates the VMFS datastore.

 iSCSI datastore issues

After creating the first datastore I noticed from vCenter that there were “Add Internet SCSI send targets” and “Rescan all HBAs” tasks showing on the hosts that I selected to add the datastore to. After watching those tasks looping for 15 minutes and datastore not showing up on the ESXi servers I figured out that there was something wrong with the configuration.

I found out that the ESXi server had datastores connected also from other storage units that use CHAP authentication. On the ESXi iSCSI initiator the CHAP settings were set to “Inherit from parent” and that meant all the new targets would also inherit these CHAP settings. After disabling the inheritance the new datastore was connected and the VMFS datastore was created on it. I haven’t tried to use CHAP authentication with VNXe datastores so I don’t know if those settings are automatically configured to ESX. VNXe already has the ability to manipulate the ESX server configuration so I would imagine that it could also be possible to change the iSCSI target option to “Do not use CHAP” when VMware datastore is created on VNXe without CHAP authentication. Maybe in next the software version?

Another issue I had was that  a VMFS datastore was not always created during the process of creating a VMware datastore. VMware Storage Wizard on VNXe indicated that creating a VMware datastore is completed but actually the “create VMFS datastore” task was never initiated on the ESX. I’ve created over 20 datastores using this method and I would say that in about 50% of those cases the VMFS datastores were also created. Not a big thing, but still an annoying small glitch.

NFS datastore

Creating an NFS datastore is very similar to creating an iSCSI datastore. The only differences are steps 2 and 5 on the VMware Storage Wizard. On step 2 NFS is selected instead of VMFS (iSCSI). On this page there are two “hidden” advanced options: Deduplication and Caching. These options are hidden under the “Show advanced” link – similar to what criticized in iSCSI server configuration. In my opinion these should be shown by default.

On step 3 the same rule applies to selecting the NFS server as with the iSCSI server. The user has to manually balance the datastores between the SPs.

On step 5 datastore access (no access, read-only or read/write) will be chosen for the host or a specific ip address on host.

When all the steps on the wizard are done VNXe creates the datastore and mounts it to the selected host or hosts. I only gave one host access to this new NFS datastore but I could see that VNXe tried to do something NAS related to all the hosts in the Virtual Center connected to VNXe and gave some errors:

VSI

In a nutshell VSI Unified Storage Management (USM) is a plug-in that integrates with VMware vCenter and can be used to provision storage using vCenter UI. There is lots of good documentation on EMC Unified Storage Community and Powerlink so I’m not going to dig any deeper into it. VSI USM can be downloaded from Powerlink – Support – Software Downloads and Licensing – Downloads T-Z – Virtual Storage Integrator (VSI). I recommend reading the VSI USM Read Me First document to see what else needs to be installed to make the VSI plug-in work.

After the VSI USM plug-in and all the other needed packages have been installed the VNXe has to be connected to vCenter. This is done from vCenter Home – Solutions and Applications – EMC – Unified Storage Management – Add. A wizard will walk through the steps needed to connect vCenter and VNXe.

Now storage can be provisioned to a cluster or to an individual ESX host by right clicking cluster/host and selecting EMC – Unified Storage – Provision Storage.

The wizard follows the same steps as the VMware Storage Wizard when provisioning storage from VNXe.

Storage type:

Storage Array:

Storage Pool:

iSCSI Server:

Storage Details:

When using VSI to provision storage the iSCSI initiators and targets are configured automatically and VMFS datastore is also created in the process.

Conclusions

Again the suitable word to describe storage provisioning would be simple, if it would work every time. After provisioning several datastores I noticed that a VMFS datastore wasn’t always created when the iSCSI storage was provisioned from VNXe. Also there were issues if CHAP wasn’t used on VNXe but was used on ESX host for other datastores. This happens when using either VNXe or VSI storage provisioning.

Storage provisioning from VNXe is easy but it is even easier using VSI. When the initial setup is done, the iSCSI/NFS server configured and the storage pool(s) created there isn’t a need to login to VXNe anymore to provision storage if VSI is in use. This of course needs vCenter and all the necessary plug-ins to be installed.

Some users might never see these issues that I found out but for some these might be show stoppers. Not all businesses have vCenters in use so they have to use the Unisphere UI to provision storage and then the VMFS datastore might or might not be created. I can imagine how frustrated users can be when facing these kinds of issues.

Also, users shouldn’t  be responsible of the decision in which SP the new datastore is placed on. This should be something that VNXe decides.

Don’t take me wrong. The integration with VNXe and vCenter/ESX is smooth and it will be even better after these issues have been fixed.

In the next part of my hands-on series I will look into the performance of VNXe 3300 and I will also post some test statistics.

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4 responses to “Hands-on with VNXe 3300 Part 5: Storage provisioning

  • Matt

    Henri – yet again, great post on your experiences. I wanted to give you feedback directly here saying I have brought up each and every enhancement you suggest within the article. It may not be in the very next release, but you have Engineering eyes on your thoughts.

    All the best,
    Matt

  • JR

    Great post (and series!).

    Would you be able to show some shots of provisioning an NFS datastore? Is it significantly different to iSCSI (does it include compression/deduplication etc)?

    Beyond the provisioning of the datastore, what other functionality does the VSI plugin provide for the VNXe? For example, can you see the compression ratio of a datastore (if enabled), or the storage paths to the VNXe as you can with the Storage Viewer plugin for CLARiiON? Finally, are you able to compress individual VMs that reside on NFS datastores like you can with a Celerra?

    Sorry for so many questions, but your blog is the first I’ve found that details the VSI for the VNXe.

    Thanks!

    • henriwithani

      Thank you JR for your comment.

      Here are the screen shots of provisioning an NFS datastore using VSI. No compression/dedup, only thin option.

      VSINFS1

      VSINFS2

      VSINFS3

      VSINFS4

      VSINFS5

      VSINFS6

      My understanding is that the storage provisioning is the only functionality for now. I haven’t looked in to the NFS side of the VSI much since we are only using iSCSI. At least for iSCSI you can see the paths and policy.

  • JR

    Henri – thank you for putting up the NFS screenshots. It’s a shame there isn’t more functionality available at the moment, but it’s a useful insight. Much appreciated!

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