3.3 Changing media

When one storage medium is full, the archive manager is warned by a mail message from the distributor daemon (subsequent message will come every hour from the archive_supervisor detecting stopped daemons). At that time, the distributor daemon and all the archiver daemons have been stopped and files that couldn't be saved by every archiver have been move to the .redist/ sub-directory in the distributor daemon working directory (see 4.2). This can be easily checked with the check_arch command.

All the media have to be replaced and initialized (labelled). Then the archiver daemons need to be restarted.

The command change_media (with no arguments) has been designed to help the archive manager to proceed changing the media. A transcript of a typical session of this command is given in figure 3.2

[IMAGE (figure)]

The change_media command first takes the whole pipeline down by invoking the kill_archive command. Although it would be possible to change the media with only the archiver daemons down, killing the whole pipeline is safer for moving the logfiles and the listfiles around.

The operator is then prompted for a new label.

The logfiles and the listfiles are trimmed and moved respectively to /archive/sw/log/old and /archive/sw/list/old .This is so as these files don't get too big and an easy access "by side" is possible.

Then the operator is asked to replace the media by new blank ones. Make sure to replace all of them and to set the write-protect tab of the old ones.

Then each media is labelled by invoking successively each media initializer. The labelling of the exabytes tapes (both TAR) is fully automatic.

Eventually the archive pipeline is restarted by invoking the start_archive command.

N.B.: The change_media script was designed to be media independant. That means that the geometry of the pipeline has to be changed (as explained in chapter 5), change_media does not need any modification.

The blank Exabyte tapes are taken from the CFHT data vault. When full, one is to be sent to CADC and the other one is stored in the vault. Usually, they are sent two by two. Just give the tapes to the accounting office. They will send it to CADC by Federal Express. A person at CADC who can be contacted is Daniel Durand. The best is to send a mail to the alias: cadc@dao.nrc.edu.