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moving IT to the cloud with service not servers

Tuesday, 28 August 2018

The problem of local file shares in a SaaS school.

For schools moving to a SaaS based model, the requirement for local files is a difficult problem to solve.

This is particularly true of established sites that have curriculum requirements and admin workflows that depend heavily on traditional Windows file shares.  Copying the data to a cloud repository sounds like a good idea but when the Year 10 Media class try to open their video projects and 20 minutes later everybody is still looking at a spinning wheel you’d better expect some negative feedback.

Whether you work in the cloud or on premises the golden rule when working with large data sets is always the same: both the data and the application have to be in the same place.

If the curriculum demands that the application is Adobe Suite or a video editing package hosted on a high end workstation then the data has to be delivered from a local store to ensure an acceptable level of performance. However after installing the file server, the failover host and the multi-tier tape backup system you may find that your bold serverless initiative is now in tatters.

The answer is to have the file shares stored in the cloud but accessed from on-site which doesn’t sound possible, but is.

One of the many storage options offered by the Microsoft cloud service is Azure Files. It’s a simple concept that allows you to define an area of storage and then advertise like a standard Windows file share. You don’t have to worry about servers or redundancy, all that is handled by the fine folks at Microsoft. Users can consume and interact with the share in exactly the same way as if the share was hosted locally which solves the first part of the puzzle but not the second.

In response to this Microsoft have announced the general availability of a new service called Azure File Sync (AFS) which is a caching engine for Azure Files. The technical details are listed here  but in simple terms an agent on a local server synchronizes the contents of a Azure File store to local storage and then keeps the two stores in sync. Files now open with the speed of local storage but are hosted on the cloud.

That’s pretty clever but the advantages don’t stop there. Using another feature termed ‘cloud tiering’ it's possible to only synchronize the files that are currently active while keeping all the old stuff in the cloud. To any user browsing the share it would appear that all the files are stored locally. Users have access to all the file properties and permissions settings just as before, data is retrieved from Azure Files only when the file is opened. Access the same file a second time and the data is now considered ‘hot’ and will be maintained on the local drive with the changes written back to Azure as a background process.

The Year 10 media class issue is solved. You have the fast response of  a local filestore while still maintaining the advantages of cloud storage.

Lets run through a few of the other advantages you get with Azure File Sync.

If implemented properly the local server is reduced to the status of a cache appliance. By only holding copies of active files it can host a multi TB share while only having a 800 GB data drive and none of the local data requires backing up. Azure File Sync come with a useful facility that will enable fast recovery of the file system onto only any suitable hardware.  By turning aging file servers into cache appliances their useful life could be significantly extended.

The Azure file store can act as a central repository for a group.  By consolidating local file shares into a central store and then synchronizing data out to edge sites you get the benefits of a local share but without the problems of maintaining an on-site data silo. In this model all backups are done using Azure Backup services (no hardware required) and users have the ability to recovery data directly using the facility built into the Windows UI.

With all this sweetness there has to be a little sour.

There are number of technical limitations that still need ironing out.  The service has a 5TB limit on a single Azure Files storage group but this is expected to be increased to 100TB in the near future.

Azure File Sync uses a simple conflict-resolution strategy as it doesn’t doesn't pretend to be a fully featured collaboration platform. If a file is updated from two server end points at the same time the most recent change will recorded in the original file. The older update will result in a new file with the  name of the source server and a conflict number appended to the original file name. It’s up to the user to manually incorporate the changes if required.

However the biggest hurdle to general adoption within education might be the question “How much does it cost”?

Subscription charges based on usage apply to the central store and prices vary between each Azure region. At the time of writing a  1TB store using Local Redundancy in Europe West will cost around £46/month  (£553 pa). Standard data egress and transaction rates apply to the central store and any additional capacity and transactions used on the share snapshots. There’s also a cost to implement Azure File Sync which amounts to £5.50/month (£66 pa) per server end-point and a charge for any additional Azure backup services you may choose to employ.

So the answer to the question is;  for a 1TB store AFS will cost upwards of £553 pa but the actual cost will depend on a whole bunch of factors which you can’t estimate until you start using it.

Let’s assume the cost is £700 pa. I think that’s a pretty good deal for a fully managed distributed file system but the problem is:  £700 pa compared with what?

How many schools understand the cost of storing data locally? To the casual observer it might even appear free. After all both solutions still require local hardware and Microsoft’s generous EDU licencing agreements makes standing up another file server a cheap option.  So the argument could be raised: why put your data in the the cloud and then commit to an open ended charging scheme just to access it ?

From a personal point of view I can think of a dozen technical reasons why it would be a good idea to implement AFS but they could all be overridden by fears and concerns over pricing and lock in.  Microsoft response to all this is simple, reduce the subsidy that education receives for local licencing until Azure looks like an attractive option. It’s a long term strategy that will win out in the end.

In the short term it would be useful if education could find a way to place a real cost on local data storage, particularly in the brave new world GDPR, so they can properly evaluate SaaS offerings such as Azure File Sync. If not they could be missing out on a good deal.