"I assume that there is a reference in the media index, because I see save sets in mminfo in with 'cr' flags. So in such case media index would not be rebuild, only its entries for save sets would be changed to browsable?"
OK, but when I run scanner I give a device as an argument. I assumed, that scanner would scan only the volume currently mounted in the device.
Correct. You must be ensure to load/insert the right media.
By 'auto eject' do you mean 'idle device timeout'? How can it be set? I don't see any such option in nsradmin for 'NSR jukebox'
It does exist ... but it is hidden by default. You must activate the hidden attributes first:
nsradmin> option hidden
Hidden display option turned on
Raw I18N: Off;
Resource ID: Off;
nsradmin> . type: nsr jukebox
Current query set
nsradmin> show idle device timeout
idle device timeout: 20;
In scanner manual there is a requirement to use 'no-rewind on close' device. An 'n' at the end of device name (for example /dev/rmt/1cbn) means that it is 'no-rewind' device, am I correct?
That's correct. If you don't do that, the tape will be rewound after each write or read. Such is nonsense for a backup device.
Concerning the media index, if it would be rebuild by scanner, what would happen with entries concerning other volumes? Would they be erased? Left unchanged? Or would Networker scan all volumes to rebuild index?
Of course you could also use scanner to rebuild the whole media index tape-for-tape. But this would mean that you have to scan hundreds or thousand of tapes to retrieve all missing info. This could take days, weeks, months ...
Consequently, the better practice is to recover from a media index backup which is part of a bootstrap save set.
'scanner' is only used to partially add data (append) for a specific volume or a save set.
To rebuild the whole media index from the bootstrap save set you use mmrecov (now nsrdr).
Bare in mind that this overwrites the existing media index. But this usually only lasts some minutes.