One last question that I am curious about is this business of the
library itself. Let's suppose you do set the max parallelism to the
number of drives on say a smaller jukebox as you suggested. You remarked
that the additional nsrjb process(es) may simply be queued up or
NetWorker may be smart enough to avoid doing it all together, but is it
possible that the library will simply refuse to do it if it knows that
it only has say two drives? For example, let's suppose you have a
library with 2 drives, and you set the value to 2 even though the
default was 1. If NetWorker refuses to honor the request to do two
simulatenous nsrjb processes even thoguh the value is 2, how is it
basing this decision? Does the library tell it not to honor it, or does
NetWorker somehow decide on its own that it it's somehow not in its best
interest to do so, so it just only runs 1 or maybe, bu not necessarily,
agrees to queue the other.

Thanks.

George

Davina Treiber wrote:
>
> On Fri, 7 Mar 2003 08:34:50 -0500, Jim Lane <JLane AT TORONTOHYDRO DOT COM> 
> wrote:
>
> >I've just read a couple of posts on this from yesterday and I'm
> >confused. the replies tended to suggest that this value should be
> >related in some way to the number of drives in the jukebox that
> >Networker should use for backup, as against leave free for ad hoc usage,
> >restores etc. I was told by the Legato consultant that this value is the
> >maximum number of saveset streams that can be directed to all the drives
> >in the jukebox at once. on that basis this number is supposed to be set
> >at or above the sum of the "target sessions" for all the tape drives. at
> >least that's what I was told. on that theory the Legato guy set the "max
> >parallelism" in my 4-drive STK 9710 to 32. now I'm worried. who's right
> >here? am I over-specifying this value?
> >
>
> Oh boy. Is this the same Legato consultant who messed you up a few weeks
> ago? The guy needs a rocket, he is talking garbage. This value is nothing
> like he says, it controls the number of nsrjb operations that can take
> place simultaneously, this includes mounts, unmount, labels, inventories
> etc. A value greater than the number of drives makes no sense at all,
> although probably doesn't do any harm. You may get nsrjb processes queued
> up waiting for others to complete - although it is possible that NetWorker
> is clever enough to avoid this situation.
>
> What the consultant has done is probably not dangerous, but totally
> misguided. It worries me that this "expert" is giving out bad advice and
> charging you for the privilege. Moreover he is giving Legato SMC a bad name.
>
> I usually set this value to the same as the number of drives. On a small
> library it is frustrating to do an inventory etc. with only one of two
> available drives. The theory of keeping a drive free for restores is valid,
> but you have to weigh up your preference. On larger libraries (10+ drives)
> it is sometimes sensible to decrease the value considerably since the load
> of running (say) 20 nsrjb processes can be too much of an overhead.
>
> You need to reduce this value to a maximum of 4. You also need to complain
> to Legato about this consultant.
>
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