Disk devices can be defined on shared network resources. If the dump is to be performed over the network, you must supply the UNC (universal naming convention) name in the form \\servername\sharename\path\filename or use a locally redirected drive letter. Make sure that you have appropriate permissions on the destination device. To ensure proper permissions, SQL Server may need to be started under a domain account (not the local system). To define the domain account under which SQL Server should be started, use the Services application in the Windows NT Control Panel.
To add multiple dumps to a single disk (file), specify INIT while issuing the first dump and NOINIT for subsequent dumps. If you are writing over a disk dump device, make sure that you use the INIT option when you perform the first dump. This allows the data on the disk dump device to be overwritten, rather than appending the dump to the end of the file.