Restoring expired save set information into client index with scanner

Follow up from the previous thread (https://community.emc.com/thread/224763 - restoring save set after retention and browse dates passed).

I decided to try scanner to restore information about expired (recoverable, but not browsable) save sets into client index. However some steps are unclear to me.

Hrvoje Crvelin wrote: 'you can always removed ssid from mdb if this is on tape (take mminfo for it before including position on tape) and then run scanner on it. scanner will ask you about position and ssid and will bring back record as if policy has been applied today.  But in general, this will take much longer.'

1. What is 'position'? Media file number and media record number?

Scanner is supposed to 'rebuild' the indexes (both media and file index). This term suggest that the whole index is modified. On the other hand for 'the -S ssid option, only entries for the specified save set are copied to the online file index'.

2. Does that mean that the rest of client index is left intact if '-S' option is used (i.e. only part of index concerning given save set is modified)?

3. What about media index in such case?

4. '-i' option modifies both media and client index. Is there no way to modify only client index by using scanner?

5. Man pages advises actually using nsrck to recover client index, and using scanner only for media index. I assume this advice does not apply in my situation?

I'm using STK SL500 Jukebox with two LTO-Ultrium-4 devices. Auto media management and auto clean is on. Two volumes (SD64LT and SD29LT) are mounted in those devices and used for current backups. Save sets I need to recover are on two other volumes (SD56LT and SD34LT). So in order to run scanner to recover for example save set from SD56LT I would need to unmount currently mounted volume (for example SD64LT) from one of devices, and then mount SD56LT there. I wonder how would it affect scheduled backups.

6. SD56LT is full and not expired - that means nothing could be written there. Is that correct?

7. What would happend if some backup was ongoing when I unmounted the volume it was written to (i.e. SD64LT)? Would unmount operation wait for the backup to complete? If not what would happen? Would part of the backup be on unmounted volume and the rest on SD29LT (the volume that is left intact)? Or would backup be corrupted?

8. Should I unmount SD56LT and mount SD64LT back after scanning, or could I just left SD56LT there?

sd@sd1:~ $ /usr/sbin/nsr/mminfo -V -s bdlbkp -m -c sdbkp

state volume                  written  (%)  expires     read mounts capacity flags

...

       SD29LT                   177 GB  22%  05/03/16    0 KB   226    800 GB

...

       SD56LT                  2412 GB full  03/03/16 3783 KB   241    800 GB

...

       SD64LT                  2218 GB 100%  05/03/16    0 KB   233    800 GB

...

SD64LT mounted on /dev/rmt/1cbn

SD29LT mounted on /dev/rmt/0cbn

I would appreciate any comments.