I have SQL Server 2008 database running in a vm guest os. Right now i have database files in vh guest vhd, which is dynamically expanding vhd.

To me i think database files in dynamically expanding vhd is not so good for performance.

Thinking of putting them on fileshare on host os so no expansion penalty.

Is it typical to put database files on fileshare?


Nope. SAN, yes. A generic network fileshare, no. In fact, it will require a bit of hacking to even get it to work, and it will almost certainly crawl. The dynamically expanding vhd is not so much of a problem - just make sure that you create your SQL Server database files so that they're not autogrowing in the middle of the day, and you should be fine (that is to say, provide enough room for growth).


It's not typical & not recommended by Microsoft.

Quoting MS KB Article 304261:

Microsoft generally recommends that you use a Storage Area Network (SAN) or locally attached disk for the storage of your Microsoft SQL Server database files because this configuration optimizes SQL Server performance and reliability.

It's not recommended so much that you need to set trace flag 1807 for SQL Server to allow it.

Dynamically expanding VHD's will another level of fragmentation at the VHD file level. It also means that your server/database may crash if you've over-sized the disks and run out of space on the physical drive.

For database files I would use drives that are:

  • Directly assigned
  • iSCSI drives
  • Worst case scenario I would least pre-allocate disk space

Well it depends. By 'fileshare' I assume you mean a mapped drive in Windows that is connected to your SQL server via an Ethernet based network. In which case, no its not normal or recommended. If however, you mean a 'fileshare' as in a volume mounted on the SQL server over something like fiber channel or other high speed media from a SAN or a NAS, then yes, it happens all the time.


Not in my experience; your network bandwidth is always going to be lower than your internal hard drive bandwidth, so you're going to take a significant performance hit.

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