Paul, we do use SSO, with one master and one media server, but we also
throw ndmp in the mix. We do indeed limit the total count of our master
and media servers to the drives actually available, 4 drives on the
master and 6 on the media server. However, since the two servers can see
all 10 drives they just choose whichever drive is available. As long as
the policies are set to use "any available server" then the jobs will go
to whichever one can grab a drive. If all the drives are busy the jobs
go into the queue. Our point to doing it this way was to split the load
over two separate gig-e pipes to the fiber where the the drives live in
such a way that NBU took care of the details of how the data gets there.
With NDMP we have it set to use paths available only on the master
server, that's just to keep it from confusing the hell out of me. (Since
we use 6mp2 ndmp allows us to use SSO)
 
David Spearman
County of Henrico,Va.

        -----Original Message-----
        From: veritas-bu-bounces at mailman.eng.auburn.edu
[mailto:veritas-bu-bounces at mailman.eng.auburn.edu] On Behalf Of Paul
Keating
        Sent: Tuesday, May 30, 2006 3:03 PM
        To: veritas-bu at mailman.eng.auburn.edu
        Subject: [Veritas-bu] SSO question
        
        
        Assuming you have several tapes drives share among several media
servers.
         
        ie, 10 drives and 3 servers.
         
        if you configure each server to see all 10 drives and then
configure a STU on each server to use a max of 4 drives, you will
encounter situations where there is demand for as many as 12
drives......In the instance where 2 of the media servers each reserve 4
drives and the third server has only 2 drives available to it, does this
cause all the jobs queued on this third server to fail with status
134??? I'm thinking that CAN'T be the case....if so, SSO would be
pointless as you would only be able to create STU's to use a total
global max of the number of physical drive you have, in which case you
may as well do fixed assignments, and not SSO.
         
        Sorry if this seems like a stupid question....I'm not using SSO
at the moment, and don't have the resources to suss it out in the lab,
and I'm expecting to be deploying two additional media servers in June.
         
        Paul

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