Our datacenters are in the range of "10's of km" and  are connected with
DWDM (actually, a SONET ring, whatever that is).  Our tape drive san is
connected by a 2gb channel (ISL link) on this dwdm.  It works very well.
We did purchase Brocade Extended Fabric feature for the switches on either
end to optimize BBCredit buffering for longer distance ISL links.  There is
a library manager TSM instance at each site to manage the shared library.
All TSM servers access both shared libraries/drives.  This as worked very
well.  At one point we did use virtual volumes (using the IP network), but
as we grew we caused performance problems for other IP traffic.  Being
isolated onto a dwdm based FC ISL link has eliminated any performance
issues of a shared IP connection.

Rick






             Thomas Denier
             <Thomas.Denier@JE
             FFERSONHOSPITAL.O                                          To
             RG>                       ADSM-L AT VM.MARIST DOT EDU
             Sent by: "ADSM:                                            cc
             Dist Stor
             Manager"                                              Subject
             <[email protected]         Remote tape drives
             .EDU>


             11/04/2008 12:55
             PM


             Please respond to
             "ADSM: Dist Stor
                 Manager"
             <[email protected]
                   .EDU>






My employer is in the early stages of planning for a move to a pair
of data centers. We are planning to have a TSM server at each data
center, with each server writing copy pool tapes on drives located
at the other data center. The TSM servers will run under either
mainframe Linux or AIX; we are still looking at the costs of the
two options. We have not picked physical locations yet, but our
selection criteria will probably lead to a distance between data
centers somewhere in the tens of kilometers.

I am aware of four options for extending FCP tape drive connections
over distances in this range: FCP over dedicated fibre, FCP over
shared fibre with wave division multiplexing, iFCP, and FCIP. I
gather that there are TSM sites with remote tape drives. Does
their experience offer strong reasons to favor or avoid
particular options?


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