Search squid archive

Re: i was wondering about the refresh_pattern Age percentage more then 100%

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



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


[Index of Archives]     [Linux Audio Users]     [Samba]     [Big List of Linux Books]     [Linux USB]     [Yosemite News]

  Powered by Linux