Even benchmarks won't help in most cases.  There's just too many
variables involved, YMMV and all that.  You just can't say whether MPX
will make restores faster, slower, or have no effect.

I still wish I knew if you had to keep DLT drives streaming DURING
READ.  This is a clue to one way MPX might actually be faster.

Imagine a client with two disks, each with it's own filesystem and
able to read/write at 5MB/s.  The network is able to transfer data at
10MB/s.  There is one tape drive on the master/media server capable of
10MB/s.  Now, which restores faster in this situation, MPX=1 or MPX=2
(where the two filesystems are backed up at the same time)?

david AT dsihost-srv01 DOT com writes:
> John you are absolutely correct!  I have no benchmark data but I don't think 
> you really need it to argue that a restore of a single contiguous stream will 
> be faster than that of its peer that has been Multiplexed with 8 other jobs.  
> 
> However, I believe that is something that needs to be decided at the Business 
> level with regards to each individual site's SLA they have with their 
> customers 
> (user community).
> 
> David
> 
> 
> Quoting John Meyers <john.meyers AT wright DOT edu>:
> 
> > 
> >  Regarding performance issues with multiplexing, I would think that the
> >  higher the number of streams multiplexed to a tape, the slower your 
> >  restore times would be due to the extra tape positioning required.
> > 
> >  I was just wondering if anyone had any data in this area regarding
> >  performance metrics associated with multiplexing multiple streams to
> >  tape?
> > 
> >  Thanks,
> > 
> >  John
> > 
> > --
> >  John Meyers
> >  Computing Services
> >  Wright State University
> >  E-mail: john.meyers AT wright DOT edu
> > _______________________________________________
> > Veritas-bu maillist  -  Veritas-bu AT mailman.eng.auburn DOT edu
> > http://mailman.eng.auburn.edu/mailman/listinfo/veritas-bu
> > 
> 
> 
> 
> _______________________________________________
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-- 
Larry Kingery 
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