VSAN – Page 45

Exploring VSAN APIs Part 7 - VSAN Datastore Folder Management

03.26.2014 by William Lam // 1 Comment

In addition to storing your Virtual Machines, you may also want to use the VSAN Datastore to store your operating system ISOs in case you do not have an external repository and would like to keep everything local. If you use the vSphere Web Client to perform this operation, you will notice that you will need to first create a top-level directory before you can upload an ISO or a file to the VSAN Datastore.

The reason for this is that the VSAN Datastore does not support files in the top level directory, so you will have to first create a top-level directory and then upload the files under that directory. To create these top-level directories, a new DatastoreNameSpaceManager is introduced in the vSphere 5.5 API which manages the creation and deletion of these directories. Once these top-level directories exists, you can then use the regular fileManager API to manage your files and sub-directories within the VSAN Datastore. To demonstrate the creation of a top-level directory and sub-directory in a VSAN Datastore, I have created a sample vSphere SDK for Perl script called vsanDatstoreFolderMgmt.pl

Disclaimer: These scripts are provided for informational and educational purposes only. It should be thoroughly tested before attempting to use in a production environment.

In this example, I will create a top-level directory in the VSAN Datastore called ISO and then a sub-directory under that called Linux by running the following command:

./vsanDatstoreFolderMgmt.pl --server vcenter55-1.primp-industries.com --username root --vsan-datastore vsanDatastore --root-folder ISO --sub-folder Linux

The script will first call the DatastoreNameSpaceManager CreateDirectory() API method which will then create the top-level directory and then using the fileManager's MakeDirectory() API method to create the sub-directory. If we take a look at our VSAN Datastore using the vSphere Web Client, we can see that our new top-level directory has been created along with our sub-directory.

For deleting sub-directories and the top-level directories, there is the DeleteDatastoreFile_Task() and DeleteDirectory() API method respectively.

Quick Tip - Don't always assume your local HDs will be claimed correctly

03.21.2014 by William Lam // Leave a Comment

For whatever reason I woke up super early this morning around 4am PST and since I could not go back to sleep, I figure I might as well finish re-building one of my lab environments. I was trying to create a VSAN Disk Group using ESXCLI, but ran into the following error: Stamping non-local disks requires a pre-created vsan cluster If I run the following ESXCLI command, we can clearly see the Hitachi disks that I have are not being recognized as a local device:

esxcli storage core device list

I already know that some disks may not be recognized as a local device which VSAN requires and this is nothing new, in fact Duncan Epping even shows you how to get around this in this article here. Seeing that it was so early in the US, I figure Duncan was probably awake and wanted to run a few things by him. It was while he was looking around in the system did he notice a stranger issue.

It turns out my local Hitachi disks were being claimed by the VMW_SATP_DEFAULT_AA (ALUA) SATP plugin which was kind of strange as I would have expected to be claimed by VMW_SATP_LOCAL instead. I decided to take a look at the SATP claim rules to see why this was the case by running the following ESXCLI command:

esxcli storage nmp satp rule list

It turns out, for identifying Hitachi storage devices, the SATP rules is quite generic and keys off of the vendor name only and hence the assignment of the ALUA SATP plugin is choosen.

VMW_SATP_DEFAULT_AA HITACHI system inq_data[128]={0x44 0x46 0x30 0x30} VMW_PSP_RR
VMW_SATP_DEFAULT_AA HITACHI system

In my opinion this can be problematic as the plugin can potentially cause strange IO or pathing behaviors as it expects one thing but is getting something completely different. I suspect this plugin was probably meant for an Hitachi storage array like an HDS instead of a local device. Once I was able to narrow this down, I just needed to create a new rule that would override the system defaults.

To verify this, I created a new rule based on the vendor name just for testing purposes which will have priority over the default system rules. When creating custom SATP rules, you can filter on a variety of attributes such as the model, transport, controller, target, adapter, etc. Depending on your use case, you may want to be generic or quite specific. The following ESXCLI command will create the new rule and assign it the VMW_SATP_LOCAL plugin:

esxcli storage nmp satp rule add -V HITACHI -P VMW_PSP_FIXED -s VMW_SATP_LOCAL

Once that rule has been added, I can now finish my original task which is to mark my Hitachi drives as "local" and reclaim these devices by running the following ESXCLI commands:

esxcli storage nmp satp rule add -s VMW_SATP_LOCAL -o "enable_local" -d [DEVICE]
esxcli storage core claiming reclaim -d [DEVICE]

If we now take a look at our device, we can see that are rule was activated and if we perform the following ESXCLI command, we can now see the device is "local":

esxcli storage core device list

The lesson here, do not assume your local devices and potentially even remote devices will be claimed correctly. There maybe vendor best practices that differ from the out out box rules and you should always do your due diligence to either verify yourself or work with your vendors to confirm the configurations.

Quick Tip - Increasing capacity on a Nested VSAN Datastore

03.21.2014 by William Lam // 2 Comments

The other day I needed to increase the capacity on one of my Nested VSAN Datastores as one of our users required a larger VSAN datastore than it was initially configured for. I was expecting to be able to just increase the size of the underlying VMDKs like I would for a traditional Nested ESXi environment and rescan in ESXi to pick up the new capacity without any downtime. It turns out, this is was not exactly the case for a Nested VSAN environment.

Disclaimer: Nested Virtualization is not officially supported by VMware

When you first setup VSAN, regardless of how the disks were claimed, VSAN will consume the entire device (SSD or MD). The capacity that VSAN initially detects will then be used to create the necessary partition as part of the VSAN Disk Group creation. VSAN assumes that the capacity for the underlying devices would never change as in the "real" world, disks do not auto-magically get larger 🙂 and this is a valid assumption. In a Nested ESXi environment however, it can auto-magically get larger but VSAN was not built for this use case. What ends up happening is that the underlying devices can be "hot-extended" but the existing VSAN Disk Group can not detect this new capacity.

Having said that, there are two ways you can increase your VSAN datastore:

Option 1 - If you wish to preserve your VSAN Datastore, you can hot-add additional VMDK(s) to your existing VSAN Disk Group or if it is full, you can create a new disk group and add additional VMDK(s). This will modify your setup slightly if you wanted a particular set of disk groups but will allow you to preserve your data.

Option 2 - The latter option requires the deletion and re-creation of the VSAN Datastore which is not ideal if you already have data on it. You will need to increase the capacity of the underlying VMDKs and then re-create your VSAN Datastore, but this way you can keep the existing number of disks and disk groups you initially created your Nested ESXi environment with.

In my scenario, I could not destroy the VSAN Datastore as I had someone using it and so I opted for option #1. Here is what my configuration looked like before which was a single VSAN Disk Group with 1xSSD and 1xMD:

I then added an additional 10GB VMDK to each of my Nested ESXi hosts and issue a rescan so the ESXi host would pickup the new device:

In just a few seconds, I can see my new storage device. I can now head over to the VSAN management page which is located at the vSphere Cluster and once I refresh, I can see that VSAN has automatically added the new "MD" into the existing disk group and my storage has automatically expanded!