Exchange 2k10 SP1 DAG Reseed

Recently I had an issue where my DAG got out of sync. First the CQL was up past 9800 and increasing.
I misguidedly deleted the log files and the CQL shot up to 187k! But at least it was going down.

After a day, the CQL had only dropped to 175k so I knew I had to reseed. Fortunately the datacenter is only a brisk walk away.

I set up Windows Server Backup to take a full snapshot of the good exchange server. This ran overnight and in the morning I brought the disk in. I removed my failed database copy and renamed its folders on the database disk. Then I mounted the VHD off the usb disk from the other server, copied the database and log directories, and remounted the database copy using this command:

Add-MailboxDatabaseCopy -Identity "Primary Mailbox Store" -MailboxServer SVR15 -SeedingPostpone

At this point I got the error: 

Registry key has subkeys and recursive removes are not supported by this method.

The fix for this was to get the GUID by:

get-mailboxdatabase "primary mailbox store" |fl name,GUID

I navigated to HKLM\Software\Microsoft\ExchangeServer\v14\Replay\State and deleted the guid's key, then retried the add-mailboxdatabasecopy command above.
It worked, but didnt show up in the System Manager immediately. I waited a bit, restarted the System Manager and my repaired database copy was there with a CQL of 967 and going down fast! Job done, beer time.