MSA log contains: CFolder::TryToLock Error 5504 Resource is already locked (73960)

MSA log contains: CFolder::TryToLock Error 5504 Resource is already locked

During an Exchange 2010 to Exchange 2010 migration MSA tries to sync the Recoverable Items folder and fails.

5/4/2011 5:41:28 PM CFolder::TryToLock Error 5504 Resource is already locked.( Folder: '', SourceKey: '4CB3DFBAB2A17F44B092C73235C6930D0000005B557C') (Folder: '', SourceKey: '4CB3DFBAB2A17F44B092C73235C6930D0000005B557C')

Afterwards, the MSA reports the following error for each mailbox that it tried to sync.

The Recoverable Items folder and the affected mailbox never syncs again. Restarting all agents does not resolve the issue.

In 8.7 the MSA will lock the root folder before it starts syncing the data, this happens as precaution, in case another MSA instance will try to do the same (as you know 8.7 allows multiple instances of the same agent).
It is not clear why MSA doesn't unlock the folder. MSA and CSA have an "unlocking" by timeout, but the default value is very high, it is 240 minutes.

MSA Does not synchronize Recoverable Items with version 8.8 and above

Possible workarounds:

1. If the source is 2010 then the suggestion is to decrease the retention of deleted items in the source, basically to keep the dumpster slim or empty.

2. Try and change the default setting manually, by adding to the config.ini of MSA (or CSA) the following entry:

MigrationLockerTimeOut=X

where X is the time in minutes.

Suggested value to try with is MigrationLockerTimeOut=20

3. Rename the tracking database for the agent. For MSA it is called EMWST.DAT and the file is in root of the disk where agent is installed (usually on C drive). If the mailbox is healthy and accessible via Outlook and OWA then renaming the tracking database and then starting the MSA again should resolve the issue.

Note: In migration where the source is Exch 2010 it was observed that mailboxes with a small dumpster (with not so many deleted items) were synchronized fine, without any errors.

Official Change Request has been created and will be implemented in future hotfixes or release of the product, a key which will allow to skip the sync of the dumpster. The CR number for this issue is ST75481.

This was implemented in case when multiple MSA instances are working, we don't want another MSA to access and to start working with a mailbox which is already processed by another agents instance. Using a lower value, eg. 5 or 10 minutes is not advisable and too risky. CSA doesn't use this mechanism so there is no need to use this for CSA. CSA will lock only the calendar folder, but eh MSA locks the root, the entire mailbox, and this is causing the trouble.