cache empties itself?
ottolski at web.de
Fri Apr 4 12:20:59 CEST 2008
Am Freitag 04 April 2008 11:50:51 schrieb Michael S. Fischer:
> On Thu, Apr 3, 2008 at 8:59 PM, Ricardo Newbery
<ric at digitalmarbles.com> wrote:
> > Well, first of all you're setting up a false dichotomy. Not
> > everything fits neatly into your apparent definitions of dynamic
> > versus static. Your definitions appear to exclude the use case
> > where you have cacheable content that is subject to change at
> > unpredictable intervals but which is otherwise fairly "static" for
> > some length of time.
> In my experience, you almost never need a caching proxy for this
> purpose. Most modern web servers are perfectly capable of serving
> static content at wire speed. Moreover, if your origin servers have
> a reasonable amount of RAM and the working set size is relatively
> small, the static objects are already likely to be in the buffer
> cache. In a scenario such as this, having caching proxies upstream
> for these sorts of objects can actually be *worse* in terms of
> performance -- consider the wasted time processing a cache miss for
> content that's already cached downstream.
> Best regards,
you are right, _if_ the working set is small. in my case, we're talking
20+ mio. small images (5-50 KB each), 400+ GB in total size, and it's
growing every day. access is very random, but there still is a good
amount of "hot" objects. and to be ready for a larger set it cannot
reside on the webserver, but lives on a central storage. access
performance to the (network) storage is relatively slow, and our
experiences with mod_cache from apache were bad, that's why I started
and so far, it works amazingly! my main problem remains that it randomly
crashed, and that the cache file isn't persistent across restarts.
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