Re: MMR: How do you tell that the MMR servers are in sync?

["Paul B. Henson" <henson@acm.org>]

On Fri, May 27, 2016 at 08:45:28AM -0400, Frank Swasey wrote:

> How are you folks, who are already using MMR, checking/verifying that 
> the MMR participants (and their replicas) are actually in sync?

To clarify, are you directing all writes to one master, or are you
actually spreading writes across all of them simultaneously?

I have my systems set up with MMR, but with a load balancer in front
such that only one node is ever actually receiving writes. I was going
to include the perl script we use to verify they are in sync, but if
you're actually running MMR with distributed writes, I'm not sure if it
would work. I've never had an issue with it when writes flipped between
nodes (on purpose or otherwise 8-/ ) and I'm sure there've been
occasions when two nodes might have gotten a few writes at the same
time, but I've never had multiple nodes receiving writes simultaneously
for an extended period of time.

Although thanks to management that believes more in audit check boxes
than actual security, we're going to be turning on account lockouts
soon, which will generate a write load on each individual server,
so I guess I'll get see what happens to my sync check script in that
case :).