# Serving big files at constant rates **URL:** \ **Category:** NGINX\ **Created:** [May 14, 2012, 2:00am UTC](https://www.ruby-forum.com/t/serving-big-files-at-constant-rates/219725 "2012-05-14T02:00:10Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![Gurdipe\_D](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/b77776/32.png) [@Gurdipe\_D](https://www.ruby-forum.com/u/Gurdipe_D)\ **Post date:** [May 14, 2012, 2:00am UTC](https://www.ruby-forum.com/t/serving-big-files-at-constant-rates/219725/1 "2012-05-14T02:00:10Z")
Hi, A recent thread kept my attention recently: > **[All workers in 'D' state using sendfile](https://forum.nginx.org/read.php?2,226327)** > > Hello, I have tried to summarize this as much as possible but it's still a lot of text. I apologize but wanted to make sure that I provide enough information to explain the issue properly. I'm hoping that somebody that uses nginx as a high... I don’t have such a big trouble, but I don’t see how to solve it. My server usually serves small files suchas classical web pages. On a particular location, though, I serve big files (around 100MB+). I noticed that when those files were served, there was ‘bumps’ in the transfer rate, whether the trasnfer stalled for 1s or the transfer rate downgraded to 500Kb/s during the same period. Those bumps were monitored server-side, so it is not some trouble in any network in the middle. I ensured that the only service using significant bandwith would be Nginx. I guess I am experiencing some disk I/O speed limitations. Thus, I tried to use aio on that location: aio on; directio 4m; output\_buffers 1m; (I tried 512k first hand) The bumps are still there, appearing randomly but quite often and regularly on the long shot. What kind of I/O trouble is that? ## Thanks, _B. R._ ---
**Author:** ![B.R](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/3be4f8/32.png) [@B.R](https://www.ruby-forum.com/u/B.R)\ **Post date:** [May 15, 2012, 5:09am UTC](https://www.ruby-forum.com/t/serving-big-files-at-constant-rates/219725/2 "2012-05-15T05:09:10Z")
Hi, I tried that, but I only see these consequences: - Higher peek transfer speed (up to 1.1/1.2 MiB/s) - Higher instability (bumps down to 300/400 KiB/s and with longer duration) - Lower average transfer rate overall ## Well, does that mean I have some network interfaces trouble? _B. R._ ---
**Author:** ![B.R](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/3be4f8/32.png) [@B.R](https://www.ruby-forum.com/u/B.R)\ **Post date:** [May 14, 2012, 6:29pm UTC](https://www.ruby-forum.com/t/serving-big-files-at-constant-rates/219725/3 "2012-05-14T18:29:56Z")
Why not create a 1gb ramdrive to make sure it is a disk IO issue. It might be a lan driver buffer issue. Posted at Nginx Forum: > **[Re: Serving big files at constant rates](https://forum.nginx.org/read.php?2,226392,226422#msg-226422)** > > Hi, A recent thread kept my attention recently: http://forum.nginx.org/read.php?2,226327 I don't have such a big trouble, but I don't see how to solve it. My server usually serves small files suchas classical web pages. On a particular location, tho ---
**Author:** ![B.R](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/3be4f8/32.png) [@B.R](https://www.ruby-forum.com/u/B.R)\ **Post date:** [May 15, 2012, 12:37pm UTC](https://www.ruby-forum.com/t/serving-big-files-at-constant-rates/219725/4 "2012-05-15T12:37:38Z")
Could very well be a lan driver issue, rx/tx values too high or rx value higher then tx, flow control not used or used but not supported, etc… try an older driver or if its really old a newer one. Also see if you can get a driver with debugging compiled in or support for raw mode and run something like wireshark to see whats going on. Posted at Nginx Forum: > **[Re: Serving big files at constant rates](https://forum.nginx.org/read.php?2,226392,226444)** > > Hi, A recent thread kept my attention recently: http://forum.nginx.org/read.php?2,226327 I don't have such a big trouble, but I don't see how to solve it. My server usually serves small files suchas classical web pages. On a particular location, tho