On Fri, Sep 26, 2008 at 04:22:21PM -0400, George Sinclair wrote:
> If you re-label a tape (not using the same volume name), what's the  
> difference between doing it this way:
>
> nsrjb -s server -L -b pool_name -S slot
>
> and the answering 'yes' when it asks if you want to overwrite, versus  
> running this instead???:
>
> nsrjb -s server -L -b pool_name -R -S slot

-R "relabels" the tape.  So it uses the same name.  You can't relabel a
non-networker labeled tape.

Without -R, you're labeling a tape, so the name is chosen either from an
explicit name (you're not providing one in your example), a barcode
label if the jukebox is set that way, or from the label template.

> I've always used the first method, although if it has an associated bar  
> code, and I don't plan to reuse the bar code label, then I always remove  
> it from the media database first to avoid associating the previous bar  
> code with the new volume. Also, I remove it first if I'm re-labeling it  
> with the same volume name.

I'm not sure why you remove it first.  When networker labels a tape, it
checks any existing label.  If one is found, it removes it from the
database because it knows the tape is about to be destroyed.

> According to the man page for nsrjb and nsrmm, the '-R' option re-writes  
> the label. Wouldn't this happen anyway? If you don't specify the '-R'  
> option then what happens? Clearly, NW has to have some way to store the  
> new volume name on the volume, right? Why would it not re-write the 
> label?

Physically, you're correct.  It does re-write the tape header to contain
a new label.

If you relabel, the database keeps the old volume statistics and moves
them forward.  I think olabel, mounts, and recycled fields all are kept
(or updated) across relables.  All will be zeroed if you delete/label
instead.

> I'd read somewhere that when re-labeling a tape that you should first  
> remove it from the database (nsrmm -d) and then tar some data to it and  
> then label it? Is this the same as using '-R'.

Nope.

-- 
Darren

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