Intermittent 503's from Varnish

[Steve Webster]

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).

See:

https://www.varnish-cache.org/docs/3.0/tutorial/handling_misbehaving_servers.html

Cheers,

Steve

-- 
Steve Webster
Web Architect
LOVEFiLM

(Apologies for the overly long and pointless corporate footer that follows.)

-----------------------------------------------------------------------------------------------------------------------------------------
LOVEFiLM UK Limited is a company registered in England and Wales. 
Registered Number: 06528297. 
Registered Office: No.9, 6 Portal Way, London W3 6RU, United Kingdom.

This e-mail is confidential to the ordinary user of the e-mail address to which it was addressed. If you have received it in error, 
please delete it from your system and notify the sender immediately.

This email message has been delivered safely and archived online by Mimecast.
For more information please visit http://www.mimecast.co.uk 
-----------------------------------------------------------------------------------------------------------------------------------------
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://www.varnish-cache.org/lists/pipermail/varnish-misc/attachments/20111107/1dbb62ed/attachment-0003.html>