Re: striping?

Henrik Nordstrom wrote:
>
> Ernst Heiri wrote:
>
> > What's the difference between 1.1.X and 1.2 causing this ?
> > (I'm still using 1.1.20 and have no experience with 1.2)
>
> The major difference is that 1.2 maintains each cache directory
> separately. You can add/remove cache directories as needed without
> wiping your cache. Squid automatically adjusts and balances the usage on
> the available cache directories.

Erm, teensy terminological note...I think it would be less confusing to
say 'cache-tree' or (better, IMO) use the keyword 'cache_dir', since
some people probably confuse the cache-buckets with the term 'cache
directory'.

> Performance differences:
> * There is is ongoing work to balance the I/O load evenly on each cache
> directory.

Mmm. And it's GOOD(!) :)

> * Squids I/O pattern is more suited for one cache directory per disk
> than a stripe. Squid primarily needs to be able to read/write at many
> different places at the same time (==lots of seeks) and keeping one
> operation/object isolated to one disk gives fewer seeks in total. Squid
> does NOT need a very high I/O rate on one single request.

Indeed. Why hash in userspace _and_ then stripe in kernelspace? Seems
like a big waste of cycles, that can be better spent serving users. No
need for raid and no funny business adding cache_dir's. Each can also be
sized individually with 1.2 (join me in a sigh of relief).

D

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