Why does amcheck fail while amdump succeeds?

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This article is a part of the Troubleshooting collection.

Problem

Errors occur with amcheck(8), but amdump(8) runs without errors.

Explanation

If you use GNUtar as backup program, Amanda uses a wrapper called runtar which should be set suid root:

# ls -l /usr/local/libexec/runtar
-rwsr-x---  1 root disk 13K Oct 28 11:59 /usr/local/libexec/runtar

Nor amcheck (on the server) nor amandad (on the client) use that wrapper, so it does not have root permissions, which means that you may get errors with amcheck(8) while amdump(8) runs through without problems.

Solution

Check for errors in the debug file named amcheck.datetime.debug (server part check) in the AMANDA_DBGDIR directory on the Amanda server host, or in the files named amandad.datetime.debug (client part check) on each client host (including the server). There are many amandad debug files; look for the one with the string "SERVICE selfcheck" in it. There should be "permission denied" errors in it.

Making the toplevel directories of the disklist entries readable by the dumpuser should remedy this. The parent directories, up to the root directory, need to be accessible by the dumpuser too.

When using local exclude lists on the client, they should be accessible and readable too. Alternatively, you can add the 'optional' keyword in the exclude list for that dumptype; this suppresses the error message.

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