We run UV on a 2-node linux HA cluster. The backup instance of UV is a cold spare, though. Failover is automatic, and less than 2 minutes, but any active UV processes are terminated since UV is started fresh on the backup node. This may or may not cause a problem for you depending on how your application is written. If your code makes use of commit and rollback, users have to repeat the process they were in the middle of but your data will still be consistent. Another consideration is the possibility of broken files when you do OS level replication. You can avoid this risk by implementing UV transaction logging (don't know about UD) or by sizing all your file so they use zero overflow. I opted for the latter in our case because it wasn't that difficult given the size of our database.
If you need your application to run continuously without any interruption, you might check into Vmware's Vmotion. We currently have two Vmware ESX servers (though not for UV) using shared storage on a NetApp SAN. Right now we're only licensing the Vmware HA capability, which automatically brings any machines that were running on one ESX server up on the other in the event of a physical server failure. Vmotion takes this a step further and migrates the running virtual machines to the other server without stopping them. I hear it works well, but we haven't opted to license it yet due to the cost. If UV or UD were implemented this way, I think that should mitigate the aforementioned broken file risk since you reduce the risk of a physical server failure interrupting a write to overflow. -John -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Baker Hughes Sent: Monday, July 26, 2010 6:38 AM To: 'U2 Users List' Subject: [U2] 24 X 7 MV systems Hey y'all, I'm interested in hearing from folks who are currently on, or have worked with fault tolerant MV systems. We'd like to host our Business Layer on the MV system and serve It to our e-commerce portals, instead of re-coding our business rules first in Basic, then in .Net In order to get there though we must meet the primary business requirement of zero downtime (not even 2 minutes to manually switch). We're not talking about different levels of Raid - it's assumed the storage array is up and available. If the MV system has a hiccup of more than a few seconds it needs to hot failover to a backup twin sister. Is anyone doing this or something close to it? When I worked in public safety, Stratus sold such an automatic hot failover. I'm sure the EnRoute folks are doing something like this still. Maybe Nick G. or Margaret M. is listening in today. Thanks, -Baker ________________________________ This communication, its contents and any file attachments transmitted with it are intended solely for the addressee(s) and may contain confidential proprietary information. Access by any other party without the express written permission of the sender is STRICTLY PROHIBITED. If you have received this communication in error you may not copy, distribute or use the contents, attachments or information in any way. Please destroy it and contact the sender. _______________________________________________ U2-Users mailing list [email protected] http://listserver.u2ug.org/mailman/listinfo/u2-users _______________________________________________ U2-Users mailing list [email protected] http://listserver.u2ug.org/mailman/listinfo/u2-users
