According to modern (American evangelical) theology, if you allow for the
existence of a single devil, then you must provide decent accommodations
for entire families, tribes, and nations of them. Way too demonic for my
secular taste.
In any case, we mirror a couple of thousand volumes with XRC via FICON DWDM
('dark fiber') at about 100 KM more or less. I believe in this technology
because it's independent of volume location within DASD subsystems that
come and go and get massively reconfigured over time. We mirror every
single volume except for a defined subset that contain either transient
'who cares' work files or data than can be recreated or kissed good-bye
without fanfare.
My own view is that DASD-to-DASD solutions are all prone to data
inconsistency in the case of abrupt failure. Unless meticulous care is
taken to put all consistency-dependent data within the scope of a single
hardware realm, however that's defined by a particular architecture, then
sudden and catastrophic loss of connection might well degenerate into the
sort of haphazard chaotic recover-by-backup FUBAR that mirroring is
supposed to have rendered obsolete in the first place.
Then again, we haven't tried anything other than XRC for the mainframe.
When you have solution that works, you don't poke sticks into its orifices.
.
.
.
JO.Skip Robinson
Southern California Edison Company
SHARE MVS Program Co-Manager
626-302-7535 Office
323-715-0595 Mobile
[EMAIL PROTECTED]
IBM Mainframe Discussion List <[email protected]> wrote on 06/15/2005
06:35:53:
> Robert Justice wrote:
>
> > We're in the middle of a DASD RFP between IBM, HDS, and EMC.
> >
> > Anyone like to share their experiences with either IBM DS8300, EMC
DMX3000
> > or HDS TAGMASTOR.
> >
> > Also would be interested in mirroring solution, XRC or SRDF/A, how many
TB,
> > and distance.
>
> Every supplier can fulfill your requirements (we don't know them), but
> the devil is in details.
>
> --
> Radoslaw Skorupka
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