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NHS Digital completes NHSmail migration to the cloud

NHS Digital’s Chris Parsons shares how the organisation managed to migrate more than 2.1 million NHSmail accounts to the cloud during a global pandemic

2020 was a busy year for the NHS, and that is no different for the behind-the-scenes staff at NHS Digital, who have successfully completed the world’s largest ever enterprise email migration – with more than 2.1 million NHSmail mailboxes moved over to the cloud. 

Chris Parsons, NHS Digital’s associate director and head of collaboration services, talks through the challenges of managing such a major project during the Covid-19 pandemic.   

We had always planned to migrate NHSmail users over to the cloud in 2020. It’s safe to say we had never planned to carry out this work during a global pandemic. 

The pandemic was never a reason to delay migration to Microsoft Exchange Online. It only emphasised the importance of the move, due to the benefits that cloud-based email would bring to NHS staff during these challenging times.   

We also wanted to move the NHS to a position that was totally aligned with the secretary of state’s vision where everything should be cloud-first, internet-facing and, wherever possible, accessible via a modern browser.

On 1 February 2021, we migrated the last batch of NHSmail accounts over to Microsoft Exchange Online in what is the largest enterprise email migration ever.

To say that we’ve completed it against the backdrop of Covid-19 is a tremendous achievement for all involved. 

Migration at scale 

The NHSmail service is used by around 80% of the NHS, as well as many other organisations across the health and care community. In total, this equates to around 1.7 million active users. 

Since August 2020, we’ve been busy migrating all of those email accounts from an older version of Microsoft Exchange (which sits inside some UK datacentres) to Exchange Online, which is part of Office 365.

We’re now at the end of our journey, which essentially involved synchronising and copying the data from where it was previously held to where it needed to go. 

The NHSmail migration in numbers

  • 2.1 million mailboxes migrated to Microsoft Exchange Online – this included active/inactive users as well as shared and resource mailboxes.
  • Hard failures (mailboxes that couldn’t be migrated): 0.
  • Soft failures (requiring reattempt to migration): 1.04%.
  • Less than 1.2% of users required support post migration.
  • 22,000 accounts migrated every evening.
  • 83,000 accounts migrated every weekend.
  • 2 petabytes of data copied to the cloud.

In total, we’ve copied just under 2 petabytes of data, which is equivalent to 10 years of non-stop 4k video footage at 30fps, or twice the size of the British Library’s digital collection.  

Each weekday night (Tuesday through to Thursday), we’d migrate around 22,000 mailboxes. Then, on a Friday night through to Sunday, we’d migrate a further 83,000 mailboxes. We’d have a rest day on a Monday and then start the whole routine again on the Tuesday.

To avoid putting an increased burden on individual trusts or Clinical Commissioning Groups (CCGs), we batched user accounts together on a random basis, rather than approaching them one organisation at a time.  

 If Leeds Teaching Hospital NHS Trust had moved over in one night, for example, that would have been a big change for them. Moving them across in a bitesize manner over four months made it a more manageable implementation for local organisations, should we have run into any issues. 

Minimising the impact on frontline services

At NHS Digital, we always try to minimise the impact of our work on frontline services, but this was more crucial than ever before during the pandemic. 

We first communicated with frontline organisations in December 2019 around some prerequisite activity they needed to do ahead of the migration. 

In most cases, this was relatively straightforward and involved them checking that the software being used by employees to access NHSmail was up to date. 

We also asked them to carry out a basic assessment of their network – to be sure that their networks were ready to take the traffic.

It was a relatively light amount of work for organisations to complete, and the vast majority of users migrated without needing any assistance at all.

The benefits of cloud-based email for the NHS

For many users, the migration took place without them even noticing. Though the difference may be slight to the user, there is no doub that this is a huge milestone for the NHS. 

Being on an evergreen platform means we no longer have to worry about updating to the next version of Exchange. Microsoft will keep the product up to date and we’ll automatically get access to new features and capabilities. 

Perhaps the biggest single benefit for me though is how it ups our game. Historically, we’ve always provided a secure email service which has done exactly what it needed to do, but email as a technology is now 50 years old, and users today rightly demand more collaborative and intuitive ways of communicating. 

We’ve seen during Covid-19 that people need to be able to work remotely and have online team sessions. Migrating NHSmail over to the cloud gives the health and care system access to the latest communication collaboration technologies available.

We can start linking NHSmail with Microsoft Teams, which has been extremely popular since it was deployed across the NHS as part of the Covid-19 response. In a 12-week period over the summer, we saw the equivalent of 773 years’ worth of audio call.

Usage of Microsoft Teams has grown so much that we now regularly see 950,000 chat messages a day, 250,000 meetings a day and upwards of 200,000 calls a day. That’s across approximately 5,500 organisations that are using the service at the moment.

A collaborative approach

In 2016, we moved from one version of Microsoft Exchange to a newer version, so we do have experience of handling a large-scale migration

Nevertheless, the success of this latest migration has only been possible due to our collaborative work with Accenture and Microsoft, which has been a tripartite approach from the start. 

We’ve worked with our delivery partner Accenture since 2015 when it was awarded the NHSmail support contract. It handles a lot of the technical management of the platform, so we’ve leaned heavily on its technical and programme teams around how to plan and implement these changes.

From a Microsoft point of view, we’ve had excellent support from both the UK and the US-based technical teams. We get direct engagement with the product groups based in Seattle, so if we have a problem with Outlook or Exchange, we can speak to the people that actually code these products and figure out what’s going wrong. 

We’ve also worked really closely with Imperial College in London and Lincolnshire Community Health Service as part of our initial pilots in June and July. This work was invaluable as it enabled us to anticipate any problems ahead of time and get them fixed before they became an issue that affects users. 

During the pilot, for example, we started to see some connection problems with people that were using unsupported versions of Outlook, which we escalated to Microsoft.

Working with the engineering teams in Seattle, we managed to understand what was causing the problem and worked with them to implement the fix.This was a great example of having caught a problem and fixing it in pilot so that it didn’t become an issue in the mass migrations.

Something that came as slightly more of a surprise to us during the mass migrations was a problem we encountered with the Apple Mail application, which didn’t behave how we’d expected it to. 

As a result, we had to pause migration for Apple MacOS users and roll 1,100 of them back onto the old infrastructure while we worked with Apple, Microsoft and Accenture to find a solution.   

In the end, we’ve had to change the approach slightly for Apple MacOS clients, but they have all now migrated successfully.

The fact that this migration took place during a time when our teams are busier than ever is a huge achievement.

To complete it during a global pandemic with very little disruption to frontline health services is testament to the commitment of all staff involved across NHS Digital, Accenture and Microsoft.

Since Teams was first enabled for NHS organisations in March 2020, there have been a total of:

  • 134,097,274 chat messages.
  • 30,448,822 meetings.
  • 13,362,020 calls.

These Teams figures are correct as of 24 January 2021.

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