Re: [Sqlgrey-users] sqlgrey fails when configured with multiple machines

[Jernej P. <jer...@ar...>]

Dear Alex,

On 30/06/14 21:19, Alex wrote:
>
>  > We have successfully deployed sqlgrey with mysql master-slave
>  > configuration, where reads were performed into slave nodes, while SQL
>  > writes were done on the master node. After a while, we ditched sqlgrey
>  > in favour of posftwd2 and hapolicy...
>
> So did you ditch it for this reason? That sounds like how I have it set
> up here. Is it not possible to create a fault-tolerant sqlgrey system on
> its own?

I think that you would need a multi-master SQL setup to be able to use 
sqlgrey in a way you are trying to set it up. The problem is that when 
mysql master goes down, sqlgrey is unable to update database and it fails.

I dont know sqlgreys' DB_CLUSTER setup anymore, but as I recall it only 
stands for offloading the read queries to other slaves as well, while 
still relying on write master to be up all the time. If write node is 
down, sqlgrey is failing...

IMHO, you have two options:
- using hapolicy with sqlgrey with default settings to DUNNO, which will 
say DUNNO if sqlgrey fails after MySQL failure
- set up HA mysql setup where write node will never fail (multi-master 
etc. - there are few options available)

I would go with hapolicy: easier to maintain and no real hassle if 
sqlgrey is failing...

>
> Would you be able to send your postfwd2 and hapolicy configs for a
> reference to get started?

Sorry, my setup is site specific, however both tools have good 
documentation and live support mailing lists, so no worries. If you hit 
a barrier, just ask a question there...

cheers, Jernej