I am, most concerned with the "copy that is perhaps miles (up to
1000's). Where I last worked (IIRC) we had approximately 160 volumes
that were XRC'd that went from Chicago to Colorado then back to NY.
The (only other) copy being in Poughkeepsie. This is old information
so it might have changed from then.
To me, the information that was bounced around the US was so out of
date it seemed like a waste of effort to do so. I know that XRC and
"dual copy" which (to me) is what you are talking about are similar. I
think the main issue is "distance, IIANM.
Lets look at it this way: the data sent remotely by PPRC or XRC might be
a few seconds (worse case a few minutes) out of date.
But if your datacenter becomes non-operational (there was another
message in this thread about a data center being bombed!!) then at least
you have your data, current to a minute or so of your live data. If you
have to depend on offsite backups, the data will probably be a few days
out of date. If the currency is so important, and the company is
willing to pay the freight, remote mirroring is a good practice.
My earlier messages were talking about local mirroring, because the
thread started talking about tape vs disk speed and related to backup
times. Local mirroring allows backups to be "created" in very little
time, and then moved to tape outside the backup window, so the tape
speed becomes less important.
--
Bruce A. Black
Senior Software Developer for FDR
Innovation Data Processing 973-890-7300
personal: [EMAIL PROTECTED]
sales info: [EMAIL PROTECTED]
tech support: [EMAIL PROTECTED]
web: www.innovationdp.fdr.com
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