Replacing apache with nginx

[mike]

On Tue, Sep 30, 2008 at 2:15 PM, Gena Makhomed <gmm at csdoc.com> wrote:

> if the shared session storage are not redundant - we must
> use sticky sessions if want avoid single point of failure

if i am user A going to server A, when server A dies, my session needs
to be migrated to server B. if server A is dead, it can't migrate.

> if one of backend servers fail - it will be marked
> as failed, but rest backend servers will works fine.
>
> the future clients requests will not be
> routed by nginx to failed backend server.
>
> but if dedicated session storage server fail -
> all backend servers can`t work with sessions...

understood; but I think you might be missing my point.

> this is reason why session affinity is better,
> if the session storage server is not redundant.

single server sessions are not redundant either. it requires migrating
session data or keeping it in two places, which is redundant - but why
not do shared then and make that redundant and simplify your load
balancing/code?

> it is not so easy to do if SQL Server is not redundant
> in multi-master mode ( for read and write operations )

depending on the size of your site you can use a two-phase plan
involving memcached and mysql, use mysql cluster, or just mysql
master/slave (not multi-master)