HA with Varnish? advice request

[john at 8t8.eu]

I'm succesfully using lvs in director mode to load balance and provide ha
for multiple varnish caches. It works really well.
On Dec 7, 2011 5:36 a.m., "Allan Wind" <allan_wind at lifeintegrity.com> wrote:

> On 2011-12-07 00:05:24, Alejandro wrote:
> > Hi guys,
> >
> > I need your advice... I'm using varnish into multiple server, some for
> > caching dynamic content and other only for static content.
> >
> > On front of the Dynamic Content Varnish y have Cisco ACE Load balancer,
> but
> > on front of the Static Varnish, the traffic is much higher and can't use
> > Cisco ACE, for this reason I'm using RoundRobin DNS into this 2 servers.
> >
> > This week I had, some network issue with one of this servers and when the
> > network go down I loose 50% of the traffic...
> >
> > here my question, or advice request... How I can have HA with 2 varnish
> > server? I'm thinking on Heartbeat or Heartbeat+ldirectord, please fell
> free
> > to send your suggestions.
>
> As your clients do not fall back to the 2nd IP it means you need
> one (active/passive) or two vips (active/active) that can be
> shared between your two varnish servers.
>
> If you have cachable dynamic content then your two Varnish
> instances may return different content to the same client.  This
> may or may not be an issue.  Others will have to weight in if
> cache invalidation of Varnish entries is a doable strategy
> (if you cannot set your expiration headers correctly).  On the
> positive side you have a warm cache should one of your Varnish
> instances fail.  With a active/passive fail over the cold cache
> may be problematic.
>
> That said I am surprised that you think Varnish will be able to
> handle your traffic but a pair of load balancers cannot.  If the
> Cisco ACE is not up to it have you looked at haproxy?  You still
> have the same vip issues, but load balancers are stateless and
> give you persistence connections to minimize differences between
> Varnish instances.
>
>
> /Allan
> --
> Allan Wind
> Life Integrity, LLC
> <http://lifeintegrity.com>
>
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