Intermittent 503's from Varnish

Steve Webster steve.webster at
Mon Nov 7 13:42:49 CET 2011

On 4 Nov 2011, at 20:33, AD wrote:

> Shouldnt saint mode return a 200 OK (stale cache item) if the backend fails and you are within the "Saint Window" for that object?  I dont think turning off saint mode is going to correct this issue.

>From what I understand, what you are describing is "grace mode".

Saint mode is the "my backend is in trouble, please stop sending requests to it" protection, whereas grace mode allows Varnish to serve up stale content for a predetermined amount of time. Grace mode is useful for serving stale content when your backend is sick, but it's also useful when Varnish has already made a backend request for that data and is awaiting a response (i.e. similar to Squid 2.7's stale-while-revalidate).




Steve Webster
Web Architect

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