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From Leif Hedstrom <zw...@apache.org>
Subject Re: proxy.config.cache.ram_cache.size query from eBay
Date Sat, 15 Nov 2014 22:48:18 GMT

> On Nov 15, 2014, at 11:22 AM, Lerner, Steve <slerner@ebay.com> wrote:
> 
> Leif,
>  
> Thanks for the response. What we are going for here is gazillions of tiny images- 76KB
average size.
>  
> We’ll try tweaking average object size… what we’d love to do is just have ATS read
from disk only and have minimal to zero RAM at all… with no swapping of course J

Don’t set it too high, or you will run out of what we call directory entries (think, I-node).
When that happens, things can either go bad, or you simply won’t be able to use your disks
full capacity :).

I’d start setting it to 32KB and see if that can hold your dataset. That would reduce your
memory consumption (and startup time) by a factor of 4x. So, roughly 27GB of RAM for the indices
should be needed.

Also remember to leave headroom for connections. Active connections consume more memory than
inactive ones. This is an area where we do poorly on configuration management as well, hopefully
we’ll introduce better connection pooling and resource recycling going forward.


>  
> Old school CDN style- our object library is so massive that this would work for us- and
as we all know its better to serve from disk closer to user than to go over network back to
origin.

Cool. Also remember that even going to origin (cache miss) over a CDN can be much faster for
the end-user, because you will retain long lived, high capacity, and large negotiated window
sizes between your CDN edge nodes and your Origin nodes. One thing to consider is to turn
off slow-start restart on your CDN nodes.

Exciting to have you guys on board!

— Leif


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