[CentOS] high availability ideas

Sat Nov 19 17:10:52 UTC 2011
nux at li.nux.ro <nux at li.nux.ro>

Les Mikesell writes:

> On Sat, Nov 19, 2011 at 5:11 AM,  <nux at li.nux.ro> wrote:
>> Thank you, however I decided to go for a less exotic setup and use a more
>> passive way of sync (probably rsync and mysql replication) and I'll do
>> the high availability part from DNS (yes, I know there are issues with this
>> solution as well).
> It can be hard to get a client to switch locations by changing a
> single IP as your  DNS response because the application may cache much
> longer than the TTL, but most web browsers are very good at dealing
> with receiving multiple IP addresses where one or more servers in the
> list do not respond.  That is, if you always give out 2 IP's but only
> one target responds, most browsers will do the right thing most of the
> time, and you can improve it by either running both sites live or
> making the inactive site do a redirect to a site-specific name for the
> active site.   And if you are writing your own client for a service it
> is usually much easier to make the client smart enough to find a
> working server than to keep a lot of data perfectly synchronized
> globally.

Les, indeed, the idea is to not only use the replica server just as a spare 
but also send traffic to it. Thanks for suggesting it.