Azure Files and IaaS Domain Controllers

Probably on of the very first VMs you deploy in your Microsoft Azure IaaS deployment are Windows Server Active Directory Domain Controllers. The Active Directory Domain Service is the foundation for pretty much every Windows server application out there, from Exchange to System Center. Running DCs in Azure IaaS works great, just remember that bit about tuning off the host caching on the disk where your DIT is.

At TechED NA 2014 Microsoft announced a new feature called Azure Files, which is currently in preview. In summary it is access to Azure storage over the SMB 2.1 protocol. Until Azure Files, if you wanted to talk to the blog, table or queue storage endpoints in Azure you had to do it via the REST API. Fine for developers, but not easliy accessible for others. What Azure Files does is introduce another endpoint for Azure storage, an endpoint that speaks the SMB protocol. So now if we want to talk to Azure Storage we can access it from any compute instance over SMB and UNC paths. So raw storage over SMB, without the need for a file server VM in between. Think of it as Fileserver-as-a-Service. Read the full announcement from the Azure Storage Group here. I wanted to use Azure Files to store a bunch of data in my lab environment in Azure, but I ran into a problem…

You access Azure Files over a UNC path where the servername is the name of the Azure Files endpoint in your storage account, the username is the name of the storage account, and the password is the access key for the same storage account. Like this:

net use \ /u:mystorageaccount <storage account access key>

When I tried to do this on a workgroup VM in Azure it worked great, same with member servers in my lab domain, but on Domain Controllers in the domain I got this error:

System error 53 has occurred.

The network path was not found.

All VMs I have tested are in the same region and affinity group as the storage account, which is also in the same affinity group. I have also tested with a storage account outside an affinity group, but in the same region; same result.

My preliminary conclusion is that “something” in how DCs handle the browsing for the network path is different from member servers or stand alone VMs. I have no root cause yet, I just thought I should write this up so that anyone else experienceing the same would have some information. Sound of in the comments if you have experienced the same or have a solution.

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