how to...accelarate randon access to millions of images?

[Sascha Ottolski]

Hi,

I'm relatively new to varnish (I'm having an eye on it since it appeared 
in public, but so far never really used it). Now the time may have come 
to give it whirl. And am wondering if someone could give me a little 
advise to get me going.

The challenge is to server 20+ million image files, I guess with up to 
1500 req/sec at peak. The files tend to be small, most of them in a 
range of 5-50 k. Currently the image store is about 400 GB in size (and 
growing every day). The access pattern is very random, so it will be 
very unlikely that any size of RAM will be big enough...

Now my question is: what kind of hardware would I need? Lots of RAM 
seems to be obvious, what ever "a lot" may be...What about the disk 
subsystem? Should I look into something like RAID-0 with many disk to 
push the IO-performance?


Thanks in advance,

Sascha