Exchange 2010 - Mailbox move takes very long

Dear all,

I am having an issue with our Exchange 2010 System. Before i explain what i am facing, I would like to let you know, that i am at an absoulte beginner level regarding Exchange. So any additonal information on how and why Exchange works in a certain way is appriciated.

Here is the problem: When i try to move a mailbox from one database to a new one it takes ages to completed. I had a look into the LOG and found this:
Log of Mailbox move
Folder initialization took about 15 hours. Mailbox is still completing. And I would like to know why? And how can I tweak this, since a lot more mailboxes are waiting for me.

Thanks in advance for your help.

Two CAS servers, Two DB servers
All running Windows Server 2008 R2 on vmware 6.5  - All Windows Updates applied until 2018-06-30
Exchange Version:  14.3 (Build 123.4) - Rollup 21 is not installed
10Gbps network connection
Storage is an all flsh SAN
Who is Participating?

[Product update] Infrastructure Analysis Tool is now available with Business Accounts.Learn More

I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

AmitIT ArchitectCommented:
I can see, mailbox you are moving is too big 6GB+ with 40K plus folders. That will obviously take time to move. Any reason for moving mailboxes?
BrummelbartAuthor Commented:
Hello Amit,

we have big database - which are filling up our storage - while only small percentage of the database is used. That's why we are moving everything to new databases. We are not using offline defragmentation, this took much longer than moving mailboxes to new databases. At least that was our experience in the past.

6GB is more or less standard in my company, and in the past moving such mailboxes took approximately one hour per mailbox.

I can see 4469 Folders, or am i wrong?
AmitIT ArchitectCommented:
No you are right, it is 4469. My bad. Moving mailbox is right idea.

Can you explain you Exchange setup, like you have DAG or Standalone server.

How is the load on source server. Are you doing during off hours.

And is this the only mailbox you are facing issue. Did you tried any other mailbox. If yes, how is the result.
Acronis True Image 2019 just released!

Create a reliable backup. Make sure you always have dependable copies of your data so you can restore your entire system or individual files.

William FulksSystems Analyst & WebmasterCommented:
Make sure you don't have a backup process running at the same time this is trying to go, as that will definitely tax the system.

Otherwise, here's an other EE question that was answered and it fixed the slow DB move issue -
AmitIT ArchitectCommented:
I suggest you to restart Exchange service on source server and test again.
BrummelbartAuthor Commented:
Hello William,

thanks for your input. I checked the settings and the RPCClientAccessServer is pointing to our NLB Cluster Ressource, which I would assume is correct. Or does it need to point to one of the specfic CAS Servers?

Backup is not running at that time and service have been restarted already, as well as each server.
AmitIT ArchitectCommented:
Are these VM server. How is NIC speed on both server. If you have multiple CAS server, better you point to one CAS server for mailbox move.
BrummelbartAuthor Commented:
Hello Amit,

Yes, they are VMs. See more Details add the end of my first post.

NIC Speed:
10GBit - all Servers
Server Load:
0 - 5 %CPU and 50% RAM  for CAS Servers
0 - 8% CPU and 75% RAM on DB Servers
DAG Setup
Yes, I think we have one, since we are hosting the same databases on two different servers and the failover is working. Correct me if I am wrong.

I have more mailboxes with this issue and some without. f.e. My mailbox is 1,2 GB and moved in approx 5 minutes.

Doing the move in off hours.
AmitIT ArchitectCommented:
Try this, you move mailboxes boxes and force it to use one CAS server at a time. This way you find out, on which CAS server you have delay. Refer:

New-MoveRequest -Identity '' -TargetDatabase DB01 -MRSServer
BrummelbartAuthor Commented:
That's worth a try.

Questions and thoughts. Maybe you have some input.

Looking at the log:
a. 23  seconds to collect all information of the mailbox and to start folder initialization
b. 15+ hours to perform the initialization
c. 17  seconds to create an initial sync point
d. 38  minutes to load all messages
e. 29  minutes to copy all messages
f. 1    second to resync
g. not listed: another 3-4 hours to complete it

What  is Exchange doing at b. and g.?
What means "initializing"? Writing index? Reserving disk space?
What means "completing"? Validating each mail again? Deleting temp files?

One thing I didn't saw at first:
Target and source mailbox aren't at the same mailbox server and the servers are displayed with differnet version. See line 4 and 6 of the log. Checked it in the shell and got following result:
Exchange server version
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today

From novice to tech pro — start learning today.