Minimal Hybrid an Alternative to Cutover/staged Migration Methods
In the early days when hybrid connections were first introduced, an administrator had to go through executing many complicated manual steps before a Hybrid Connection was created. To simplify matters Microsoft introduced the new Hybrid Configuration Wizard (HCW) in Exchange 2010 SP2. This was a significant first of many steps gone in to improving hybrid setup experience and has since encouraged many in configuring, deploying hybrid connections.
In 2015 Microsoft decided to release Hybrid Configuration Wizard (HCW) as a separate downloadable tool to ensure that the user experience remains consistent across the supported exchange versions and hybrid configuration wizard code was not tidy up with exchange cumulative updates. This allowed Microsoft to release frequent fixes and new features without breaking exchange environment. The user experience with HCW has seen many improvements since then. It is probably true that setting up hybrid configuration is much easier today than it was in the early days.
New Hybrid Migration Methods
In the mid-2016, Microsoft updated HCW and added a new migration method now knows as “Minimal hybrid”. Now recently the “Express Migration” feature was also added in the HCW to further improve and simply migration experience. The new Express Migration experience is only available with minimal hybrid method.
On launching the HCW first time, now you are presented with two options under the “Hybrid Features” page.
– Full Hybrid
– Minimal hybrid
Unlike cutover/staged migration, the mailbox migration experience with minimal hybrid is like full hybrid where users are not disconnected during migration, OST files are retained (no user profile recreation is needed) and the cross-premises mail flow is not interrupted.
The minimal hybrid method can only be used in performing mailbox migration and hybrid administration only. The minimal hybrid doesn’t provide enhanced Hybrid features like Cross-Premises Free/Busy, eDiscovery, Secure mail flow, etc. Use Full hybrid if these features are needed.
Think of using minimal hybrid for small to medium size customer to enhance the mailbox migration experience where previously cutover/staged migration methods were considered but not Widely used due practical limits and risks associated from these methods.
Minimal hybrid configuration can be easily converted to full hybrid by rerunning the HCW again but it is not possible to convert other way round.
Express Migration Experience
Express migration experience is a new migration experice added to HCW and is only available if minimal hybrid was selected. Think of using this for a small size customer who wanted to migrate all on-premises exchange mailboxes to Office 365 and do not wish to keep directory synchronisation around. During users provisioning we are presented with an option “Synchronize my users and passwords one time”. This option is considered as express migration experience. The new express migration experience is accessible from within Office 365 admin portal by selecting exchange option under “Users” and then “Data Migration” section.
The Express migration is ideal for customer who wanted to migrate all mailboxes to Office 365 in less than two weeks. Consider using this as a replacement to cutover and staged migrations for a customer who wanted to migrate all exchange data to Office 365 and an on-premises directory synchronisation and exchange is not required for recipient management.
Directory synchronisation is supported with minimal hybrid but express migration only supports one-time directory synchronisation. If directory synchronisation is required, then considered using another migration method.
Minimal Hybrid Considerations
Staged migration is not supported for newer versions of exchange, e.g. exchange 2010 or 2013 and this is where you can consider using minimal hybrid instead of using cutover migration. The requirements for minimal hybrid are like full hybrid with the same complexity level, therefore one may just consider deploying full hybrid for best user experience.
There are many factors involved in deciding which migration method is best suitable. In most cases the business requirements dictate which migration method is suitable for the migration activity. It is a big topic on its own and requires dedicated blog but for now remember, the following migration methods are available.
- Full Hybrid – Previously known as Hybrid
- Minimal hybrid (New)
- 3rd Party
The threshold of cutover/staged migration method is 2000 users but migration activity of this size is considered too risky due to practical limits. In the real world, usually 100-150 is considered practical number by experienced Office 365 consultants.
For minimal hybrid, I would recommend to apply whatever you apply for cutover/staged migrations but consider full hybrid when the size of the organisation reaches above 200.