[squid-users] cache_replacement_policy ==> Clarification Please & Thank You

I have read through the notes in the default config file notes on the topic.
Here's the notes from the file:

> # TAG: cache_replacement_policy
> # The cache replacement policy parameter determines which
> # objects are evicted (replaced) when disk space is needed.
> #
> # lru : Squid's original list based LRU policy
> # heap GDSF : Greedy-Dual Size Frequency
> # heap LFUDA: Least Frequently Used with Dynamic Aging
> # heap LRU : LRU policy implemented using a heap
> #
> # Applies to any cache_dir lines listed below this.
> #
> # The LRU policies keeps recently referenced objects.
> #
> # The heap GDSF policy optimizes object hit rate by keeping smaller
> # popular objects in cache so it has a better chance of getting a
> # hit. It achieves a lower byte hit rate than LFUDA though since
> # it evicts larger (possibly popular) objects.
> #
> # The heap LFUDA policy keeps popular objects in cache regardless of
> # their size and thus optimizes byte hit rate at the expense of
> # hit rate since one large, popular object will prevent many
> # smaller, slightly less popular objects from being cached.
> #
> # Both policies utilize a dynamic aging mechanism that prevents
> # cache pollution that can otherwise occur with frequency-based
> # replacement policies.
> #
> # NOTE: if using the LFUDA replacement policy you should increase
> # the value of maximum_object_size above its default of 4096 KB to
> # to maximize the potential byte hit rate improvement of LFUDA.
> #
> # For more information about the GDSF and LFUDA cache replacement
> # policies see http://www.hpl.hp.com/techreports/1999/HPL-1999-69.html
> # and http://fog.hpl.external.hp.com/techreports/98/HPL-98-173.html.
> #Default:
> # cache_replacement_policy lru

I really don't understand the difference between:
cache_replacement_policy lru
&
cache_replacement_policy heap LFUDA

*Question 1*
In the description above under heap LFUDA above, is it implying that the
default lru setting somehow takes into account the size of the files as
well?

> . . . heap LFUDA policy keeps popular objects in cache regardless of their
> size . . . .

*Question 2*
Does lru just dump the largest files first?

As I am more interested in caching larger files, (like windows updates), and
after reading this submission
<http://squid-web-proxy-cache.1019090.n4.nabble.com/recommended-memory-cache-replacement-policy-tp1039362p1039368.html>

I was thinking of using this setup:

> cache_replacement_policy heap LFUDA
> cache_dir ufs /var/spool/squid3_cache_1 51200 16 256
> cache_dir ufs /var/spool/squid3_cache_2 51200 16 256
> cache_dir ufs /var/spool/squid3_cache_3 51200 16 256
> cache_dir ufs /var/spool/squid3_cache_4 51200 16 256
>
> memory_replacement_policy heap GSDF
> maximum_object_size_in_memory 2048 KB

*Question 3*
Have I placed the replacement policy tags in the correct place - ie. above
the cache_dir's and maximum_object_size_in_memory?

Thanks for the assistance

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