On 20 May 1998, James H. Cloos Jr. wrote:
> >>>>> "Eric" == Eric Stern <estern@packetstorm.on.ca> writes:
>
> Eric> space in the swap file is allocated in 1000 byte increments.
>
> Why 1000 rather than, say 1024? :)
It was a nice round number for debugging with. :) I've changed it to 1024
now.
> Since you're essentially writing a custom filesystem, you might want
> to look into making it log-structured. Perhaps a simple fsck as well.
> Certainly it is OK to just have to get the data from the src should a
> disk crash, but killing the entire cache because of a squid crash is
> less appealing.
Intestingly, it IS log structured. Squid already keeps a log of things
written into the cache, so the whole thing just fell into place. When you
shutdown squid, it removes the current log and writes a new one that is
competely accurate. But, if you don't get that chance (squid crash), there
is a still a possibility that you can use the old log file to recover
objects from the swap file. I'm working on this.
> Although 32-bit systems would be limited to a single file of not more
> than 2G, an option to mmap(2) the swap files would be a performance
> win. (Hmm, an Alpha or UltraSparc, FC/AL controller, couple of dozen
> 18G Cheetahs, devfs, a driver to expose each disk (not just partition)
> as an mmap(2)able character special file, full HTTP/1.1 compliance....
> Now *that* is a cache box!)
>
> I hope all these ideas/comments do not come off as overwhelming. I'd
> certainly volunteer to help. (As you might guess, I've been thinking
> along these lines as well....)
Not just you. Apparently the squid dev team has been talking about it for
some time. No one had time to do it. :)
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Received on Thu May 21 1998 - 12:06:39 MDT
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