Handling Second Copy Tape Media in OSVault

OSVault has the ability to make two copies of every file, and to make sure that each file is on separate physical media.   There are some good reasons to do this:

• Tape is not infallible, although we have not had an LTO-4 or LTO-5 tape fail on us
• A second copy of files can be taken offsite to guard against catastrophes
• Sometimes humans make mistakes and erase media that is still needed

To Make Second Copies

The first step in setting up second copies is to create a Volume Group called "copy2"
and placing some of the tape media in that Volume Group.  Note that you can put
a tape in this copy2 Volume Group even if it has been used already.

You can then add a second copy tape migration task to OSVault from the GUI by
creating a new tape migration and putting a "2" in the "Extra Copy" field.

How when the task scheduler runs a copy2 tape migration, every file that has already been copied to tape as a primary copy will be copied again to a tape in the copy2 Volume Group.  A separate migration report will be generated if you wish to see the results of that tape migration task.

What To Do With Second Copy Media

Generally, once a tape in the copy2 Volume Group is full (or almost full), you should EXPORT that tape and stored it somewhere else.  There is little reason to leave the tape in the library, since OSVault will not automatically use that tape.  

How To Restore A File From the Second Copy Media

We are working on a GUI button to help with this, but until then a CLI procedure is available to restore the second copy.  This CLI procedure swaps the two extended attributes that show where a file is stored on tape, changing the values of "mig_filename" to the second copy location, and putting the previous primary location in "copy2".  Here's an example:

First make sure the file has a second copy, either by viewing the File Location Report or with the following CLI:

      attr -g copy2 /cache/testfile

Then, you can make the next retrieval of the file go to the copy2 media with:

    PRIMARY=`attr -g mig_filename /cache/testfile`
    COPY2=`attr -g copy2 /cache/testfile`
    attr -s mig_filename -V $COPY2  /cache/testfile
    attr -s copy2 -V $PRIMARY /cache/testfile