Zero Cost Storage for Cloud VDI

Introduction

During my years in IT there has been a constant stream of promises from companies that go out of their way to grab ones attention but often deliver very little. Marketing is obviously needed, but it has got to the point where now I rarely get excited at outrageous claims from companies  You could say I have ‘hype fatigue’.

Having said that, there are companies whose technology will genuinely help improve customers’ IT systems in a variety of ways.  I have been reviewing such a technology to fully understand what it means and more importantly, who it can help.

Cloud Storage

Cloud providers see storage as a lucrative means of incremental revenue and let us face it this is a necessary component we cannot do without.  Gone are the days where adding another very expensive hard disk for your storage array makes any logical sense.  It is true the convenience of simply paying for more cloud storage and it magically being added is worth paying for but in real terms there are many hidden costs that are not always obvious when considering your overall storage requirement.

For instance, many administrators assume that Cloud storage is similar to storage on their on-prem hypervisor and storage systems which allows them to provision thin storage and grow as need dictates.  WRONG! At least if you are using Microsoft Azure.  To be fair to Microsoft this used to be the way prior to 2017 when they brought in managed disks.  Although there are advantages to using managed disks, boy do you pay for them!

The biggest difference in terms of cost between manage and unmanaged disks is that with unmanaged (Standard Storage) disk you will only be paying for the data saved to it.  For instance, you could have a disk that is 500GB in size but if only 20GB of data was saved to it you would only get the bill for the 20GB of data.  You could think of unmanaged disks as thin provisioned disks.  The introduction of managed disks changed all that so if you have a managed disk that is 500GB in size you will pay for 500GB regardless of if you use it all or not.  That stings a lot.

To be fair to Microsoft they have recognised this and have created smaller (Regarding disk Storage) images on the Azure Marketplace to at least help with some of the cost.  Unfortunately, these smaller disk sized images are only for Windows Server images at the moment and are limited to 30GB System disks.  This is helpful but why can’t we have smaller Windows 10 images?  I have always been taught that apps should reside on a separate volume from the OS anyway but perhaps that’s old school however old habits die hard as they say. Even now I like to see only the OS on the system drive. In the old days we even moved the page file to a faster drive.  I think we can all get a little distracted by detail but every little helps.     

But wait…… have I unknowingly been transported to a parallel universe where not only Cloud storage is free but also it also provides massive performance benefits?  Apparently, I have.  OK… there are a few considerations but for the world of Cloud VDI we could be looking at a game changer. 

Ephemeral Disks

Let me introduce, Ephemeral disks.  These disks are a feature of Microsoft Azure.  They have been around for a while but what are they?  Well….. as their name suggests they are disks that are considered as temporary disks and are created directly on the hypervisor’s local storage as opposed to the Azure storage fabric.  Because they are created on local storage, disk performance is a lot better when compared to managed disks.  This is presumably because managed disks run on massive storage arrays and the data would have to negotiate all those switches and networking complexities as well as being at the mercy of the contention policies set in place due to multi-tenancy and all this prior to being processed.  It’s clear that storage that is close to the processor is never going to be beaten for performance.  It is as simple as that. 

So, what does this mean to Cloud VDI?  The first thing to make clear is that ephemeral disks are temporary which means that persistent VDI will not take advantage of them.  As a side note and, in my view, nobody would seriously consider persistency in a production VDI environment as there is no means of central management of the OS and more importantly the apps.  Anyone with real life VDI design experience will always favour designing Cloud VDI with non-persistency at the heart of the design, simply because of the advantages this brings.  That is why good profile management is key to reducing uniqueness of the VM’s themselves.  Non-persistent VDI is the only way to go in my view, but this means that Azure ephemeral disk can be utilised and you will see the performance benefits immediately.

Early Testing of Ephemeral Disks

Our early testing has focused on deployment speeds.  At Cycloud we are all about rapid provisioning and deprovisioning of VM’s and we will do anything to make this as fast as possible which is why we are so excited about ephemeral disks.  So far we have seen some incredible performance increases when comparing ephemeral disks with managed disks.  On average we have seen around 40% shorter provisioning times with ephemeral disks which frankly has blown us away.  We have also seen some significant operational performance increases but as we are still evaluating the figures, we would prefer to delay the results until we have had time to crunch the numbers further, but we are confident of seeing impressive increases in performance at that level also.

Summary

Ephemeral disks are one of the best additions to the Azure Cloud we have seen.   Are the benefits of ephemeral disk too good to be true?  No, they provide huge performance gains when compared to managed disks, but the best part is, they are free.  Ephemeral disks also follow the Cycloud methodology of totally deprovisioning cloud resources when they are not being used.  We not only support the use of ephemeral disk within Cloud VDI deployments we actively encourage the use of them wherever possible.

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