If you ever encounter a error similiar to this;
C:\>vzctl start 204
Starting VPS ...
Virtuozzo API function call 'VZVolumeMount' failed err = 183
Virtuozzo API function call 'dq_mount' failed
Cannot set disk quota for VPS 204

The issue is that Virtuzzso is not able to determine which filesize is correct. It first looks at the file size from the primary *.efd file and also the quota limit that is set in the quotalimit for the VEID. However at times if the *.efd is changed the quotalimit at times will not and vice versa. So far I’ve only ever noticed it in Virtuzzso 3.5.1, but it could also occur in 4.0.

The fix is to manually set a quotalimit to the veid. To do this you will need to drop down to a command line. Once you do that you will need to force the change as I’ve done in the example;

C:\vzquota setlimit 203 -B 5684930 –drive C:\

You can change this accordingly, as long as you use the vzquota command to set the correct quota size. You can also set it higher first and then change it back to the correct size.

This command updates limits for the running Container quota. It requires at least one limit to be
specified.The syntax of this command is:
vzquota setlimit CT_ID -B num [--drive name]
The following options can be used with the command:
-B, –block-hardlimit num Required. Specifies the disk quota block hard limit, in 1 Kb
blocks. This limit cannot be exceeded by the Container.
–drive name Optional. Specifies the disk drive inside the Container for
which the disk quota limit is to be set.

For its execution, vzquota setlimit requires only the ID of the Container and the disk
quota limit to be specified. However, you can additionally use the –drive option to specify
to what Container disk drive the defined quota limit is to be applied.

To verify it set you can then run vzquota stat VEID or vzquota show VEID (VEID is the number of the VPS).