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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 17:10:23 GMT

> On Nov 13, 2014, at 4:40 PM, Lerner, Steve <slerner@ebay.com> wrote:
> 
> Hi gang- Phil Sorber referred me to this list.
>  
> We are setting up clusters of Apache Traffic Server to beef up the front end of our image
services which are… large in terms of volume… to say the least.
> We hope to be the big users of ATS and be a strong reference customer- so any help with
is appreciated!
> Our first test cluster consistes of 23 machines, ubuntu12.04, Intel(R) 2x Xeon(R) CPU
E5-2670 v2 @ 2.50GHz, 128G ram, 95T disk


That is a lot of disk :) With default settings, you would consume roughly 110GB of RAM just
for the indices. The calculation is

   (95*10^12 / 8000) * 10


Take comfort that with squid, you would use 10x as much (128 bytes per index entry). But you
have three options:

1) increase the records.config setting for average object size. That is the 8000 number above.
Doing so means you can store fewer objects in the cache.

2) buy more RAM

3) reduce disk capacity on each box

I thought we had a wiki entry on this subject?

Cheers,

-- Leif 
>  
> Here is our query:
>  
> We are setting records.config as: CONFIG proxy.config.cache.ram_cache.size INT 64G
>  
> But we find that trafficserver ignores this limit and grows at the default rate of 1MB
RAM / 1GB disk.
>  
> Example of a current process:
>  
> traffic_line -r proxy.config.cache.ram_cache.size returns 68,719,476,736
> Which is about 64GB- correct!
> 
> But looking at the process:
>  
> 86050 nobody    20   0  108g 102g 4912 S   54 81.3   1523:33 /ebay/local/trafficserver/bin/traffic_server
-M --httpport 80:fd=7
>  
> So basically we’ve set the process to only consume 64GB but its consuming 108GB…
> 
> Does anyone have any ideas on why this happens or a way to fix it?
> We want to have constrained RAM but tons of disk- we’d much rather have the cache serve
from disk then start swapping RAM
>  
> Thanks in advance,
>  
> Steve
>  
> Steve Lerner | Sr. Member of Technical Staff, Network Engineering | M 212 495 9212 |
slerner@ebay.com | Skype: steve.lerner
> <image001.jpg>
>  

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