Hi,
I am creating documenting for the procedure of patching/upgrading a two node cluster running Windows 2008 R2 Enterprise. I thought my work was done but then realised I need a backout plan.
I understand that in a cluster upgrade the patch is installed to the passive node where it upgrades the SQL program files, then when the SQL instance is failed over it will automatically upgrade itself because it is sitting on upgraded program files. I guess this is when a major SQL service pack is applied, or can this also happen with hotfixes or cumulative upgrades?
Do windows OS service packs or patches cause a SQL instance upgrade?
The MAIN problem is that if the SQL instance is upgraded it makes the backout very tricky. This is a small-scale financial banking system, and we don't want to lose any transactions. The procedure I'm creating has a prereq of "no downtime", unless it's the
merest blip when the SQL instance fails over. Obviously I can uninstall the service pack/hotfix, but I'm still left with an upgraded SQL instance.
Are there any alternatives to restoring the original SQL instance from a backup? I'm guessing that will require deleting the later version and restoring an earlier version, and will cause downtime.
These are virtual machines so snapshotting beforehand would be an option, but that also needs to be done when SQL is down and would also cause downtime.
Both options also risk losing transactions when the new instance is discarded for the old one.
Can anyone advise?
Thanks!!
Steve