Citrix has an absolutely fabulous disaster recovery story. Leaham Brothers were using Citrix as a front end in the World Trade Centre on 11 September 2001. They had a DR site across the Hudson River in Jersey. Their world Trade Centre site unexpectedly went off line. They were back up and running 20 minutes later and did not lose a transaction.
Here is how they did it:
There was a Citrix farm with a zone in the WTC and a zone in the DR Site.
The production file and database servers were in the WTC and the DR ones on the DR site. All servers had their data on EMC SAN Disk. There were EMS SANs in the WTC and DR site.
The EMC SANs were connected by fibre and they were writing each transaction to both SANs so they were both real time.
When the WTC site went off line the administrators in the DR site pointed the remaining Citrix servers to the DR File and Database servers, all of which could see the EMC SAN in the DR site. Once this was done users could get in to the Citrix servers on the DR site and work as though nothing had happened. (Even if the world had changed forever.)
Note that both Citrix Zones were in active/active production use and load balanced until the disaster. This of course required a good link between the two sites.
Backups were done with tape drives on the DR site as the data was off site already.
Citrix has some great White Papers on this and their own DR set-up. Check out their web site at www.citrix.com
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Copyright © 2007, 2008, 2009 Mark Ellis www.citrixexpert.com.au info@digitalharmony.com.au