SBS 2003 to SBS 2011 Migration – 50Gb of Public Folders to Migrate took a week to migrate!

Having nearly completed yet another SBS 2003 to SBS 2011 Migration after the longest week of my life so far, I was amazed at how slowly the Public Folder Replica Move actually took to push 50Gb of data between the two servers.

Starting the project on a Monday and having the SBS 2011 server built by Monday afternoon (built virtually using Microsoft’s Hyper-V Server on a new HP ProLiant ML350 G6), I started to move the Exchange Mailboxes and then the Public Folder Replicas to the SBS 2011 server.  The network was originally running on a 10/100 Switch but I upgraded it to a Gigabit Switch on the Tuesday morning so that I had the maximum speed available and both servers had Gigabit cards in them.

At the end of the Tuesday, there were still dozens of Public Folders listed in the Public Folder Instances list in the Exchange System Manager, so I checked the SMTP Virtual Server Settings to see if there were any settings configured that might slow the process down and discovered several settings that would restrict the flow of emails.  The initial setting that I noticed was the “Limit session size to (KB):” setting.  This was limited to 40Mb and as some of the emails in the Public Folders were in the region of 30-40Mb in size, the session size was going to severely impact the flow of mail so I changed it to 1024000 (about 1Gb).

The other setting that I changed was the “Connection Timeout” value on the General Tab.  This was set to timeout after 10 minutes, so I increased the timeout to 2 hours, so that this wouldn’t cause any delays either.

I wasn’t unduly concerned at this point about problems with inbound mail and spammers clogging up the system as I had already installed a SAN/UCC SSL certificate (minimum 5 Domain Names) bought from www.exchange-certificates.com and had re-pointed port 25 to the SBS 2011 server.

So having made as many changes to the network and SMTP Virtual Server Settings (also restarting the Simple Mail Transport Service) I created a new Receive Connector on the SBS 2011 server to only receive mail from the IP Address of the SBS 2003 server and set the Maximum Message Size Limit to 50Mb and let the two servers talk to each other.

Sometime overnight on the Saturday after starting the migration, the whole 50Gb of Public Folders had migrated across to the SBS 2011 server and all the Public Folder Instances had disappeared!  A whole 5½ days later.

At one point during the PF Replication, I calculated that it was moving at about 500Mb per hour, so all in all, it was going to take in the region of 100 hours to move the entire database.

So – if you are planning a migration from SBS 2003 to SBS 2011 and you have a large Public Folder Database, don’t expect the migration to complete quickly.  Assuming the worst – a Public Folder Database with 75Gb of data in it, I would expect it to take about a week and a half just to push the data to the new server.

Happy migrating!

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