I ran into a problem with SQL Server restore operations recently. I got burned for quite a while, because I thought I had a problem with my SQL Server 2000 and SQL Server 2005 installation, a SQL Server or O/S version issue, or a problem with my database backup file. Small SQL backup files restore fine, but large backups fail on the restore on VPC images
When I restored the large backup files, ISQL RESTORE DATABASE commands fail with the following symptoms:
- Msg 3241, Level 16, State 37, Line 1 The media family on device ‘C:\Temp\MyLargeDatabase.bak’ is incorrectly formed. SQL Server cannot process this media family.
- The media set shows a Backup Set Name of *** INCOMPLETE ***
- RESTORE HEADERONLY FROM DISK=’C:\Temp\MyLargeDatabase.bak’ returns BackupName of *** INCOMPLETE ***, Position = 1, the rest of the fields are NULL
Virtual PC Shared Folders corrupt files! Especially large files. Small files seem to work fine. I’ve heard reports of problems with files over 1GB to 4GB in size. My database was around 8GB.
You get the errors shown above when you reference a file across a VPC Shared Folder, or when you create a local VPC file copy by copying a file to your VPC disk over a Shared Folder connection.
Copy or reference files using a traditional networking file share between the host and guest, and avoid using Shared Folders for large files (or altogether).
If you think you may be having a similar issue, you can use a tool like SlavaSoft’s fsum to perform checksum comparisons file on the host and guest systems to verify what’s going on. Or you can take my word for it and save yourself the trouble. I’ve experienced this (the hard way) with Virtual PC 2007.
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