Many well-known backup utilities for Windows use the Volume Shadow Copy Service built in to newer versions of windows to create a point-in-time snapshot of the disk in order to safely back up open files.
But how well does this mechanism play with SQL Server? I know that an SQL Server VSS Writer exists to help backup systems interoperate with SQL Server, but not all backup systems know about SQL Server and take advantage the backup-related API that it provides.
So my question is, what about the programs that don't know anything about SQL Server?
They presumably get a point-in-time snapshot of the MDF and LDF files as they existed at one single instant. And presumably the SQL Server data format is robust enough that such a snapshot would be guaranteed to be consistent and usable.
Is that the way things work, or am I missing something? Are there "gotchas" about using such a backup mechanism, or would I be safe?