Re: Cobalt

On Sat, 3 Oct 1998, Stefan Rompf wrote:

> At 21:16 03.10.98 -0500, Brian Feeny wrote:
>
> >async I/O as in an async filesystem? Is that a reality on linux yet?
> >Ultimitley, the plan is to grow a "farm" of Cobalts. I like the idea of
> >multiple processors/machines for speed and redundancy. Could you comment
> >for example, would 2 CacheRaQ's of the above config do better than my
> >squid box? I know my RAID0 Ultra/Wide disk array is superior to an
> >UltraATA single drive, but I was thinking some of whats lost in the cobalt
> >could be made up with the 64bit processor, dma io, and possibly a farm of
> >cobalts (a la alteon).
>
> Using multiple caches for load splitting is a VERY bad idea because you
> will not only share the load, but also the hit ratio. There is no chance
> setting up a sibling relationship between all boxes as this will give more
> load to every box than a single system has.

Not necessarily true. The switch would keep track of which request was in
which cache, so it would be linear.

>
> If you need redundancy, use a second cache that can overtake first's IP
> address or do some magic with the browser's proxy auto configuration (this
> won't work for MSIE). For caching, a "real" computer which allows you to
> add another SCSI drive easily seems more usable than a Cobalt box. PCI SCSI
> and ethernet controllers use DMA since decades ;-)

I am not sure you understand how Alteon et al switches work. It does more
than divide requests amongst caches. If a request comes in for
"www.netscape.com" and the alteon has not seen this before, it sends the
user to whichever cache, lets just say cache #1.

Now, whenever another user comes in requesting www.netscape.com, the
alteon knows that that was served by cache #1 so it directs the user to
cache #1. Its works this way for all requests, so you don't have
redundant objects, or even need ICP peering between the caches in the
farm.

>
> cu.. Stefan
>
>
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>
>

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Received on Mon Oct 05 1998 - 16:12:40 MDT