[CentOS] Noise Cancellation of Server Noise

Sun Dec 25 04:25:50 UTC 2016
John R Pierce <pierce at hogranch.com>

On 12/24/2016 5:24 PM, geo.inbox.ignored wrote:
> temperature regulated fan speed can reduce noise.
> use of a baffle box with styrofoam or thin foam rubber lining.
>         -----+-----+
> fan  \/     |     |
>       /\  |     |
>         --+-----+---
>           ^     ^
>           baffles
> spacing between upper and lower baffles must be equal to or larger
> than diameter of fan so as to not restrict flow. also, making
> enclosure 2" larger than fan will help reduce restriction.

he said 'server rack'.    thats a probably 6' tall cabinet filled with 
servers, each of which has likely dozens of high speed fans.

(back of 2 server cabinets I used to run at work...)

(front of one of those cabinets,

a cabinet like that needs 600 cubic feet/minute or more airflow.

now, I'm guessing that H's rack isn't quite this big, or as densely 
populated, since its not in a dedicated server room, but still, it has a 
lot more than a couple fans to silence.   my rack there has 8 servers, 2 
additional disk trays, and about 200 disk drives, also a pair of 7000 VA 
UPS's in the bottom (actual load was around 3000VA)

john r pierce, recycling bits in santa cruz