I’m merrily working away on installing SQL 2008R2 on a bunch of new clusters. The SQL installs have gone fine and I’m getting set to install MSDTC, one for each SQL instance (read the awesome post by Cindy Gross on this).

The install of MSDTC went smoothly and it seemed very happy. Then I failed over the cluster…

MSDTC failed.

It wouldn’t restart.

I failed back to the original node and it wouldn’t start there either.

What’s the error?

I dumped the last few minutes of the cluster log by opening a dos box command prompt and running…

cluster log /gen /span:5

 

This dumps the last five minutes of cluster logs into C:WindowsClustercluster.log

I scrolled through to get to the MSDTC error piece:

INFO  [RES] Physical Disk: Failed to get vol MP root for path ?, status 123
ERR   [RHS] Error 123 from ResourceControl for resource <instance>_MSDTC.
WARN  [RCM] ResourceControl(STORAGE_IS_PATH_VALID) to <instance>_MSDTC returned 123.

I checked the disk resource for MSDTC and it was online. Looking at the filesystem on that disk and there was an MSDTC directory, so I knew there were no access problems. It didn’t make any sense.

So what’s going on?

The key error here is the failure to get MP root for path ?

Apparently MSDTC is not supported does not work with Mount Points, which is what I had set the dependency to. There were no warnings on this when setting MSDTC up and I’d not seen or heard of any documentation that speaks to this.

I was finally pointed to a Connect item opened by someone who’d had the same issue https://connect.microsoft.com/SQLServer/feedback/details/576545/msdtc-fails-to-restart-in-sql-server-2008-r2-clustered-group

_{Side note: I love it when Connect items such as this are closed as by design. Why is this by design? Can someone explain to me why MSDTC shouldn’t be supported on Mount Points?}

I deleted the MSDTC resource and added it again, this time using a regular drive as a dependency and everything worked perfectly. I was able to failover and have SQL perform distributed transactions.