[lug] Setting up failover in Linux?

Rob Nagler nagler at bivio.biz
Tue Apr 24 15:54:45 MDT 2012


In looking at various "high availability" solutions, it seems that
software configuration is left up to the application.

Consider this situation with DRBD: during a database upgrade, the
primary fails.  What software has been installed on the secondary at
this point?  If you installed the latest software on the primary,
because you are doing the db upgrade with/for it, then if you are
using DRBD on /usr, the secondary has the software.  If it doesn't,
then it still has the old software.  Now consider this: perform a db
upgrade, primary fails just after the commit, that is, the database is
consistent and copied over to the secondary.  What state is the
secondary's software?

I've looked at Veritas, for example, and it seems to ignore the
problem of software updates entirely.   Oracle doesn't deal with it
either.

What I want is a failover solution which takes into account all the
app data and code.  I haven't seen such a solution.  Have you?

Thanks,
Rob



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