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From "Lerner, Steve" <>
Subject RE: proxy.config.cache.ram_cache.size query from eBay
Date Sat, 15 Nov 2014 02:32:38 GMT

Makes perfect sense- thanks! In the mix of ye olde alchemy are there any favorite levers to
pull for ATS that are known to impact overall RAM use?

We won’t bother the list anymore about this after this question ☺ Thanks for the help!


Steve Lerner | Sr. Member of Technical Staff, Network Engineering | M 212 495 9212 |<>
| Skype: steve.lerner
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From: James Peach []
Sent: Friday, November 14, 2014 7:07 PM
Subject: Re: proxy.config.cache.ram_cache.size query from eBay

On Nov 13, 2014, at 6:40 PM, Lerner, Steve <<>>

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
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

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.

proxy.config.cache.ram_cache.size just sets how much memory to use in the RAM cache, as YongMing
points out, there's lots of other things in the system that will consume RAM. Unfortunately
tuning the RAM usage seems to be a bit of a black art :-/

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 Lerner | Sr. Member of Technical Staff, Network Engineering | M 212 495 9212 |<>
| Skype: steve.lerner

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