July 27, 2009 at 7:32 am
I have been tasked to look into High Availability options to use with the ERP software we develop. Our software has one DB which holds global information and additional databases for each company which exists within our application (similar to Great Plains). The ODBC Native Client allows a mirror to be specified but as we have more than one DB this is of no use.
Does anyone know of a easy way to resolve this problem or will we need to add additional code to product to allow mirror DB's to be specified?
Any thoughts are greatly appreciated.
Thanks,
Ally
July 27, 2009 at 8:53 am
You can mirror multiple databases. If you have them in high availability mode, they'll stay in sync. Why won't this work for you?
July 27, 2009 at 9:15 am
Sorry Steve, perhaps I didn't explain myself properly. I'm trying to find a way to connect are client software to multiple mirrored databases, with as little additional development as possible. There are now issues configuring database mirroring at Instance level.
I think to be honest I'm clutching at straws and will have to raise a job with our dev team to resolve this. Thanks for you prompt response.
Ally
July 27, 2009 at 9:27 am
The client software shouldn't know, or care, about if they're on the primary or mirror. If you are using updated ADO or SNAC clients, then you put in the mirror and principal.
If you have
ServerA.db1 (principal)
ServerA.db2 (principal)
that mirrors to
ServerB.db1 (mirror)
ServerB.db2 (mirror)
If ServerA goes down, the clients would redirect to Server B. If db1 goes down on ServerA, but not db2, the clients would redirect their db1 queries to ServerB, continue to hit ServerA for db2.
If your clients cannot redirect, then clustering works well for an entire instance, but it has other issues, like shared storage, expensive to distribute, etc.
A low tech, log shipping solution works as well, but it requires some manual failover. Not much better than mirroring here.
the other low tech is that you make sure everyone connects to an FQDN (full qualified DNS name) and if you have issues, you change the DNS, flush cache, people go on.
July 27, 2009 at 9:32 am
Cheers Steve, I have tested Clustering within Virtual Server. The main client which is interested in this has the budget for clustering but seem to lean more towards mirroring. I shall look into the options further and carry out some more testing. Once again thanks for your help.
July 27, 2009 at 9:38 am
You are welcome, and happy to help. If you have more questions, or just want to run something by us, feel free.
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