Re: [squid-users] i was wondering about the refresh_pattern Age percentage more then 100%

 On Wed, 23 Feb 2011 07:03:02 +0200, Eliezer wrote:
> i have seen refresh_pattern with Age percentage more then 100% and
> my question was:
>
>
> does that percentage does an extending to the expiration time?
>
>
> or squid has maximum of 100% limit?

 No. Limit is 1 year. So if % of past age is over 1 year it will be
 cropped back to that 1 year max.

>
> i have seen people writing unreasonable and ridiculously patterns for
> cache like:
>
> refresh_pattern -i (get_video\?|videoplayback\?|videodownload\?)
> 5259487 999% 5259487 override-expire ignore-reload reload-into-ims
> ignore-no-cache ignore-private
>
> it means "save the file for 3652(days) = 5259487(minutes)/60/24" am i
> right?

 Yes they are ridiculous.

 Not for the reasons you seem to think.

 For an object 10 sec old when Squid received it that % would keep it in
 cache and trigger a when it reached 100 seconds old (10sec * 9.99
 rounded to 1 second).

 The max-valud caps this % but 100 seconds is less than N days, so
 nothing happens there.

 The min-value then kicks in raises that to "minimum 3652days". Which is
 ridiculously long period to go *without validation*.

 To get a properly fresh content large % and/.or max-value are
 reasonable but such high min-value is usually not a good thing.
 Definitely not a good thing to do without deep analysis of the websites
 the pattern catches.

>
> no harming anyone but it seems kind of weird.

 It is harming their clients view of the websites which match that
 refresh_pattern regex. Particularly when those ignore-* and override-*
 are used as well.

 In the case given it is a youtube (with youtube clone sites as
 collateral damage) and a lot of very deep analysis has been done to
 ensure that the patterns for those videos does no damage to the user
 experience. Quite the opposite. Our adoption and publication of those
 rules was a last-resort after a year of discussion attempting to get
 youtube to present cache friendly controls on their site fell through.

 Amos
Received on Wed Feb 23 2011 - 05:56:44 MST