tag:blogger.com,1999:blog-8554856838676547482.post6494109665754016057..comments2024-03-13T23:27:27.652-07:00Comments on Reverse Beacon: What Happened During Sweepstakes?Pete Smith - N4ZRhttp://www.blogger.com/profile/02411300024370511509noreply@blogger.comBlogger1125tag:blogger.com,1999:blog-8554856838676547482.post-77631155084625877742010-11-23T08:44:17.353-08:002010-11-23T08:44:17.353-08:00Hi Pete,
I'd be curious to know more about t...Hi Pete,<br /> I'd be curious to know more about the back-end system you are using (VPS available memory and bandwidth to the net). My rough calculations lead me to believe its not an upload bandwidth issue. Assuming 40 characters (bytes) per spot and 5.5 spots per second I figure thats 220 bytes/sec uploaded from the skimmers. It may be less depending on how/if the skimmers compress their upload packets.<br /><br /> Assuming a lowly T1 line was your connection to the internet at a max 200 Kbytes/sec capacity, that would allow you to receive 5000 spots/sec burst, almost 1000 times your reported average. My guess though is you're sitting on a circuit with 10-100 times that capacity if you're with a large cloud computing provider. So I would think upload bandwidth isn't the issue.<br /><br /> A more important question is how many viewers/users are connecting, 100, 500, 1000, more? That would dictate your outgoing traffic, among other resource needs. Again at 220 bytes/sec (per those 5.5 spots) that could require 22 Kbytes/s, 110 Kbytes/s, or 220 Kbytes/s respectively for outbound traffic for each quoted number of users above. That latter number would just saturate a T1 connections outbound capacity, but would be easily handled by a large cloud provider who may have upwards on 10 MBytes/s capacity to the internet, or 50x your max needed capacity to support 1000 users.<br /><br /> It would seem that you may be up against a memory limit on your VPS. I'm unsure how your system works, but I'll quote numbers off a Linux system I use, some daemon knowledge and a worst case scenario. Knowing you allow users to connect with telnet, I spawned a telnet daemon and checked the memory footprint it requires to handle one user connection. Its ~2 Mbytes. Now the next question is how much memory is allocated to your VPS? 256M, 512M, 1024M, more? A good portion of that will be allocated to running the O/S, the web server (say Apache), maybe a DB (say MySQL). Assume though for the discussion those take no memory. <br /><br /> The 3 quoted memory allocation above would allow for roughly 128, 256, or 512 users respectively. Once you exceed that your O/S will start swapping memory and processes out to disk. That is a BIG performance hit and will soon bring your system to its knees, with very little chance to recover, given the continuous traffic you say the system digests and relays.<br /><br /> Without knowing any real numbers about your system this is just a shot in the dark, but I've seen many instances of servers that were under equipped to handle the memory requirements of a system. Hope this sheds some light and let me know if I can be of any assistance.<br /><br />73<br /><br />andyz - K1RA<br />http://www.k1ra.us/AndyZ - K1RAhttps://www.blogger.com/profile/05062907666638857018noreply@blogger.com