Thanks everyone for your comments and links. Rudy
-----Original Message----- From: owner-u2-users-dig...@listserver.u2ug.org [mailto:owner-u2-users-dig...@listserver.u2ug.org] Sent: Wednesday, April 08, 2009 1:00 AM To: u2-users-dig...@listserver.u2ug.org Subject: U2 Users Digest V1 #2597 U2 Users Digest Wednesday, April 8 2009 Volume 01 : Number 2597 In this issue: [U2] Replication Re: [U2] Replication RE: [U2] Replication RE: [U2] Replication ---------------------------------------------------------------------- Date: Tue, 7 Apr 2009 09:12:29 -0700 From: "Cooper, Rudy" <rudy.coo...@sagepub.com> Subject: [U2] Replication Hello, I have a concern about our uv server suffering a catastrophic hardware failure. Our uv server is responsible for our order processing & shipping, core to the business. We can't afford much down time. Is anyone replicating UV data to another server or using any kind of 'snapshot' technology? If so could you provide some info. Thx, Rudy ------------------------------ Date: Tue, 7 Apr 2009 11:45:27 -0600 (MDT) From: "Karl Pearson" <ka...@ourldsfamily.com> Subject: Re: [U2] Replication This may not be real helpful, but for a warehousing business, they thought it was nice. I setup an NFS server from the business system (AIX 5.2) to the Web server (Fedora v8) and then setup a cron to copy the entire business system applications and data every night at about 11pm, which was when the database was unused by other processes, or anyone actually changing things. For the developers, I also created a web link to the source code (BP file) so they could, after entering a login and password, view the source code. Doing that saved the necessity of having to put a tape in the drive and waiting for a couple hours to see if a file was restored so they could see what it looked like before so-n-so edited things... This company didn't have a development server, so they did work on the live business system. Yeah, lame... HTH, Karl On Tue, April 7, 2009 10:12 am, Cooper, Rudy wrote: > Hello, > > > > I have a concern about our uv server suffering a catastrophic hardware > failure. Our uv server is responsible for our order processing & > shipping, core to the business. We can't afford much down time. > > > > Is anyone replicating UV data to another server or using any kind of > 'snapshot' technology? > > > > If so could you provide some info. > > > > Thx, > > > > Rudy > ------- > u2-users mailing list > u2-users@listserver.u2ug.org > To unsubscribe please visit http://listserver.u2ug.org/ > - --- Karl Pearson ka...@ourldsfamily.com Owner/Administrator of the sites at http://ourldsfamily.com - --- "To mess up your Linux PC, you have to really work at it; to mess up a microsoft PC you just have to work on it." - --- ------------------------------ Date: Tue, 7 Apr 2009 11:53:34 -0700 From: "John Hester" <jhes...@momtex.com> Subject: RE: [U2] Replication > -----Original Message----- > From: owner-u2-us...@listserver.u2ug.org > [mailto:owner-u2-us...@listserver.u2ug.org] On Behalf Of Cooper, Rudy > Sent: Tuesday, April 07, 2009 9:12 AM > To: u2-users@listserver.u2ug.org > Subject: [U2] Replication > [snip] > > Is anyone replicating UV data to another server or using any kind of > 'snapshot' technology? > > If so could you provide some info. We're doing real-time replication rather than using snapshots, but the goal of avoiding downtime is the same. There was a long thread on this topic back on 3-18, so I won't post all the details of our implementation again, but I'd be happy to resend my post to you off-list if you don't have it. To summarize: While you can use 3rd party software to replicate UV at the OS level, there is an important issue to consider. Writes to overflow space of a hashed file require more than one write operation, as do on-the-fly automatic resizes of dynamic files. If the live server goes down when only one or some of these writes have been completed, the replicated copy of the target file may be broken, possibly beyond repair. Turning on UV transaction logging can eliminate this danger, but there is an important issue to consider here as well. Dan Fitzgerald pointed out that if you are copying the logs to your backup machine as they're closed and rolling the transactions forward, you will almost always lose the last transaction because it is likely to span 2 log files and will be seen as incomplete. If I understand correctly, however, this issue applies to a hot-spare scenario where UV is actively running on both servers. We use a cold-spare where UV doesn't run on the backup machine and the data filesystem isn't mounted. IBM's recommendation to me was to use transaction logging and replicate the logs to the backup machine along with the UV data. In a failover scenario, UV would be "warmstarted" on the backup machine and only the active transaction log would need to be rolled forward. There is some I/O overhead associated with transaction logging, though, and it's non-trivial to implement. My workaround at this point has been to: 1) insure dynamic files are only used as inconsequential report work files, and 2) insure that no hashed files use any overflow space whatsoever. This was not too difficult since I'd resized all our important files last year. It was just a matter of tweaking our existing custom file.stat report to show anything with groups in the 125% column or above. It probably took me about 4-5 hours over the course of 3 days to cover every file in the database. Now all our hashed files look something like this: Groups 25% 50% 75% 100% 125% 150% 175% 200% full 0 4431 30386 206 0 0 0 0 I check the weekly file.stat report each Monday for any file that may have grown into overflow space. - -John ------------------------------ Date: Tue, 7 Apr 2009 12:47:28 -0700 From: "Tony G" <1tlx6h...@sneakemail.com> Subject: RE: [U2] Replication Rudy, you just missed a long thread in this forum on exactly this topic. A link to the forum thread is here: http://www.pickwiki.com/cgi-bin/wiki.pl?HotBackup HTH T > From: Rudy.Cooper > I have a concern about our uv server suffering a > catastrophic hardware failure. Our uv server is > responsible for our order processing & shipping, core > to the business. We can't afford much down time. Is > anyone replicating UV data to another server or using > any kind of 'snapshot' technology? ------------------------------ End of U2 Users Digest V1 #2597 ******************************* ------------ u2-users-digest mailing list u2-users@listserver.u2ug.org To unsubscribe please visit http://listserver.u2ug.org/ ------- u2-users mailing list u2-users@listserver.u2ug.org To unsubscribe please visit http://listserver.u2ug.org/
