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From Phil Sorber <sor...@apache.org>
Subject Re: proxy.config.cache.ram_cache.size query from eBay
Date Fri, 21 Nov 2014 02:10:30 GMT
On Sat Nov 15 2014 at 2:23:13 PM 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
>
> If you want, you can set that RAM cache size setting to 0 to disable it. I
think you will see a noticeable slowdown though, unless your RAM cache has
a 0% CHR.

You will still have memory usage from the directory and other objects,
however.


>
>
> 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.
>
>
>
> -Steve
>
>
>
> *Steve Lerner* | Sr. Member of Technical Staff, Network Engineering | M
> 212 495 9212 | slerner@ebay.com
>
> | Skype: steve.lerner
> [image: Description: logo]
>
>
>
> *From:* Leif Hedstrom [mailto:zwoop@apache.org <zwoop@apache.org>]
> *Sent:* Saturday, November 15, 2014 12:10 PM
>
>
> *To:* users@trafficserver.apache.org
> *Subject:* Re: proxy.config.cache.ram_cache.size query from eBay
>
>
>
>
>
> 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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