Re: [squid-users] How much disk space is reclaimed by the cache replacement algorithms?

Thanks for the reply, Matus.

Few more questions inline:

On Wed, 2009-12-23 at 08:58 -0800, Matus UHLAR - fantomas wrote:
> On 22.12.09 17:45, Manjusha Maddala wrote:
> > Using LRU replacement policy,
>
> I hope you use at least "heap LRU" which is more effective.
>
> > I see many of the cached webpages for my
> > site getting evicted. Could someone here tell me:
> >
> > 1. How often is the replacement done?
>
> when the percentage of configured cache_dir size crosses the cache_swap_high
> value.

So if my cache_swap_high is set to 96 and cache_dir is set to 100GB,
only when the cache_dir size grows beypnd 96GB will the replacement task
begin - is that right? Lets say I have 8 cache_dir directives in my
squid.conf each pointing to a different directory. Now, if one of those
directories is over the cache_swap_high value while all others are below
cache_swap_low, will cache replacement work on just the first directory
or on all others as well?
>
> > 2. Lets say the cache low water mark is set to 95, I understand that
> > once the disk usage exceeds 95%, cache replacement kicks in. Once the
> > process is completed, what would the disk usage drop to?
>
> the cleaning stops after cache usage falls under cache_swap_low value.
>
> > 3. I notice some pages in the cache_dir which are over a month old.
> > Doing a "curl" to the squid cache with the URL of the cached page causes
> > a TCP_REFRESH_MISS/FIRST_UP_PARENT entry to be logged in the access log.
> > Which means, the page has become stale (by the refresh pattern rules) on
> > the web cache and a new page is fetched from the parent site. From this,
> > I infer that the page hasn't been referenced in the last one month and
> > yet hasn't been marked for cache replacement while other newer cached
> > pages have been flushed out. Why's that?
>
> apparently nobody asked for it and previous cleanings removed older objects.
>
Received on Wed Dec 23 2009 - 18:38:13 MST