Concurrent and other limits for migration batches

[Mike Rowland]

Just a question as the information online is hard to get a clear answer...

Someone else in my organisation has started staging migrations for a large user group, they are creating a single batch at a time (i.e. one user per batch)

If we're running staged migrations is there a hard limit of how many can sit paused at 95% in my migration console?

I can see there is a max 300 concurrent batch limit but do paused/staged migrations count towards that 300?

Also as I read it there is no limitation to the number of mailboxes inside a batch? So best practice certainly wouldnt be to create a 1:1 user - batch process?

[#2 · Accepted solution]

In general, there is a concurrency limit of 300 per migration endpoint. So, assuming you have only one migration endpoint, yes. You can have migration batches running (i.e. running, queued, paused), each utilizing different migration endpoints, increasing throughput.

* If we're running staged migrations is there a hard limit of how many can sit paused at 95% in my migration console?
No, it can be more.

* I can see there is a max 300 concurrent batch limit but do paused/staged migrations count towards that 300?
No - it's a concurrency limit for the mailboxes concurrently being migrated or periodically synced, through an endpoint.

* Also as I read it there is no limitation to the number of mailboxes inside a batch? So best practice certainly wouldnt be to create a 1:1 user - batch process?
The CSV is limited to 2000 entries. Batches are formed to group users you want to migrate together. In practice, groups are usually formed by dependencies (boss/secretaries), business units, geographical location, etc. It's a lot of overhead to create a batch per user, but if that works for your organization.

[#3]

Hi Mike,

You can create Batches by Department for Example or per First Letter of the user.

Yes you have a limit of 300 concurrent migrations - https://support.microsoft.com/en-us/help/2797784/how-to-manage-the-maximum-concurrent-migration-batc...

You can read here the best practices to do a migration - https://technet.microsoft.com/en-us/library/dn592150(v=exchg.150).aspx

[#4]

There is an endpoint on which he can perform 300.
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