Tape Input-Output error

This article is a part of the Troubleshooting collection.

Problem

amdump(8) and amflush(8), or any application accessing the tape drive, give "Input/output error" messages, such as.

  taper: tape weekly-002 kb 0 fm 0 writing filemark: Input/output error

Solution

Most in-kernel tape device drivers do not provide very detailed errors back to an applications. Often EIO ("Input/output error") is the catch-all "something went wrong" indication. This can indicate something benign like end-of-tape, or more serious problems such as a failing tape drive (see How To:Diagnose a Failing Tape Drive), bad cabling, or even a hapless operator removing a tape from a running drive.

Amanda guesses how large a dump will be, and uses the "length" parameter as an estimate of tape size. The dump estimate can change on a system in constant use, and tape cartridges can contain a bit more or less tape than advertized (due to stretch, etc.). So sometimes Amanda, despite its best intentions, writes off the end of a tape. When this happens, you will often see a message like "Input/output error," and in this case the error is fairly benign -- Amanda will keep the dump on the holding disk (you do have a holding disk, right?) and flush it to tape on the next amflush or, if you have "autoflush yes", on the next amdump run.