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Wednesday, August 4, 2010

2 Media Families are Expected

I’ve just got a couple of 1TB drives (WD Caviar Blacks…woohoo!) as my new boot stripe and I’m getting prepared to start builing my new workstation.

I stage many of my spike solutions on this machine, so I need to backup my web sites and databases that are used to show these snippets of functionality off and allow users to play-test them.  There are usually 3-4 of these active at any given time.

Through SSMS I tried to backup one of the databases and got the 2 Media Families error:

The media loaded on "c:\path\database.bak" is formatted to support 1 media families, but 2 media families are expected according to the backup device specification.

I’ve run into this before, so I had a good inkling that there was a bad backup set.  This isn’t good news if you’re in a production environment, but it’s not so bad in my case.

While it’s not “fixing” the issue, you can get around this error by performing the following steps:

  1. Remove the existing/offending backup locations from the list.  You can do this in the backup task window or by generating a backup script and removing the DISK="your_bad_path" from the command.
  2. Specify a new backup filename in a pre-existing folder.  If the folder doesn’t exist you’ll get an OS3 error with no text, but it just means you’re trying to write to a directory that doesn’t exist.

The NOFORMAT, NOINIT, NOREWIND texts come from tape backup origins and the documentation is not really clear on how they affect system drives.  For example, the MSDN documentation suggests that using FORMAT will render the media set useless.  So what does that do to my C:\ drive?  FORMAT will rewrite the headers for instances where there are different media family counts (whereas INIT will not).

So, I maybe don’t want to use FORMAT?  I don’t have a striped backup set of tapes, so I don’t think this matters.

At any rate, I don’t need whatever corrupt backup file was on my disk, so I changed my destination, removed the bad file from the backup list and carried on.

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