Extremely Slow Exchange Database Plug-in Restore

Environment:

Avamar Version: 7.1.0-47

Agent: 7.1.100.370

Exchange VSS Plug-in: 7.1.100.370

DDOS: 5.4.4.2-453843

Exchange Server: 2010

Exchange Host Server OS: 2008R2

     Here recently, December 2014, I restored one of our Exchange Databases via the Exchange Plug-in as flat files, not an RDB.  The restore was EXTREMELY slow, in the past it would take about 4 hours, the DB is roughly 750+ GB,  this time it took over 14 hours 41minutes at a rate of 49.46GB an hour .  I had a few other Exchange Database restores to do and one took as long as 36+ hours, the DB was still in the 750+GB range.

     So now I get into the troubleshooting mode.  In the same time window I upgraded Avamar versions, 7.0.0-427 > 7.1.0-47.  We save our backups on a Data Domain, which the DDOS has been upgraded as well, 5.4.0.4-388934 > 5.4.4.2-453843.  Below are the following steps I have taken:

• Restored to another Exchange Server, I let the restore run for about four hours, I was already able to tell the restore was not going to be any quicker.
  • Same slowness
  • This shows the issue is not on a specific client
• Restored to a server that I temporarily installed Exchange server, only to be able to perform the restore because the plug-in required Exchange to be installed, performed a restore
  • Same Slowness
  • This shows the issue is not on a server that it's main function is Exchange and with any load
• Upgraded the Avamar Agent and Exchange Plug-in from 7.0.100.427 > 7.1.100.370, tested another restore
  • Same slowness
  • This shows the Agent and Plug-in version is not the issue
• Restored the DB from our DR Avamar node to our DR Exchange server
  • Same slowness
  • This shows the issue is not just on our PD Avamar node, but on both.
• Created a file large enough to give me an idea how quick it could restore, about 160+GB.  Backed up and tested a restore. I did this to see if this issue is only with the Exchange Plug-in or a different Plug-in.
  • 158.4GB restored in 1 hour and 36 minutes with a rate of 98.09GB an hour.
  • This was better, but I don't have any history of other larger files even close to the 799GB DB to tell for sure.
• Backed up the Exchange DB to the Avamar Node instead of on the Data Domain, the next day I did a restore to the server I temporarily installed Exchange on
  • The restore performance was a LOT better.
  • 698.0GB restored in 1 hour and 36 minutes
  • This tells me the Data Domain is the issue, at least so far from the steps I have tried.

     Are there other steps I would need to try that you see I haven't tried?  I looked at the DDOS release notes on the version we are running now and new versions.  I haven't seen anything mentioned about resolving and known issue.  Is there anyone that has seen this and has a possible solution?  I may have to end up opening a ticket, I just wanted to poll the masses to see if anyone else has had this issue.