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I have a tape drive connected directly to a server, which have a lot of static data. I.e. the data won't change during the backup window.

Does Amanda still need a holding disk?

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up vote 2 down vote accepted

I would say yes. One important reason for a cache like this is to allow the backup program to consolidate all data it needs to backup and write it to the tape in one continuous operation. This prevents the tape drive from having to start and stop all the time while the backup program is searching for data to write, which in turn is important because it will have to go back a little on the tape to find it's correct position when starting again, a process called shoe shining for obvious reasons, which puts a lot of wear on both the drive and the tape.

Modern drives are told to be much better at this because they slow down before their write buffer runs empty, reducing the shoe shining effect, but I would still try to prevent it wherever possible.

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Do I need to keep the files that Amanda puts in the holding disk for as long as I want to preform incremental backups? – Sandra Jul 16 '11 at 11:24
Sorry, but I am not an Amanda user and don't know if and how holding disks are used beyond data consolidation. Scanning over the docs, it appears it's a lot more complicated than with i.e. Baculas spool files. – Sven Jul 16 '11 at 12:26

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