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help locating bottle neck
#1
Hello. First of all PVR WMC is great. It is the closest of anything yet to replace my stbs from the cable company. I am hoping that some of you may be able to assist me. The problem i am having is occasional buffering on HD channels. I have a ceton infinitv 6 with a cable card and my server is an 8 core AMD with 8 gigs of ram a 7200rpm 1tb HD. My clients are raspberry pi running raspbmc. When running multiple streams the buffering obviously gets worse (I have 6 PIs). I think the bottle neck is either the hard drive or the RAM but I am not sure how to narrow it down. Does anyone know how I might be able to tell before I purchase more RAM or a SSD? I know this is not an issue with pvr DMC but I hoping someone might have a suggestion. Thanks.
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#2
(2013-11-30, 04:01)Aslan2120 Wrote: Hello. First of all PVR WMC is great. It is the closest of anything yet to replace my stbs from the cable company. I am hoping that some of you may be able to assist me. The problem i am having is occasional buffering on HD channels. I have a ceton infinitv 6 with a cable card and my server is an 8 core AMD with 8 gigs of ram a 7200rpm 1tb HD. My clients are raspberry pi running raspbmc. When running multiple streams the buffering obviously gets worse (I have 6 PIs). I think the bottle neck is either the hard drive or the RAM but I am not sure how to narrow it down. Does anyone know how I might be able to tell before I purchase more RAM or a SSD? I know this is not an issue with pvr DMC but I hoping someone might have a suggestion. Thanks.

Is this a start up problem, or after the live tv stream starts does it suddenly freeze and start buffering? How many clients need to be running before this starts to be the issue? Is it a wired network?
Windows Media Center PVR addon (pvr.wmc) and server backend (ServerWMC)
http://bit.ly/serverwmc
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#3
It occurs after the stream has started and freezes some times for just a few seconds then starts again sometimes it is longer like 30 seconds. It is a wired network and it becomes noticable with 2 or more streams. I should also note that my server is handling a few other functions as well. It is a webserver that gets very little traffic, runs sick beard, couch potato, newznab, and mysql. I have been leaning toward the hard drive as the bottle neck because I will notice it even with one stream going if there is a lot of hard drive activity. For instance if a large movie file is being moved to the NAS or unpacked. If that is the case so you think a dedicated SSD just for PVR.wmc to use would do the trick?
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#4
Well yeah! Your hard drive is being thrashed when you are unpacking files and moving large files. I have a ssd as my primary drive, and a 1 tb for recorded TV. I think the best is just to put all your media that you will be streaming to your clients on a separate drive/s. And only do large transfers to those drives when no one will be watching TV. I wouldn't go as far as putting all media on ssd's, well....probably would if I had that kind of scratch HuhSmile
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#5
Lol. well it seems pretty obvious when you put it that way. I have a nas that I use for TV shows I get from sickbeard and was thinking that maybe I could create a hard link to the nas for my recorded TV folder. Either that or just break down and buy a second drive like you said just for recording TV.
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#6
Either way you should be fine. Forgot to ask if the rasbpi's are wired or not. If you are wired to a gigabit lan, under ideal conditions you should theoretical be able to stream HD TV to around 70+ clients. That's just calculating raw transfer speeds on a typical new large capacity hard drive. Not sure how to factor in iops but I'm sure that 6 clients should not cause a bottleneck on your lan. If you are on a 100 megabit lan or wireless then yes, you will likely see some buffering if streaming HD TV to all six, even more so if you throw in some HD bluray rips.
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#7
what is your nas? I run a syno 212j and I off load all nzb suite to it. it does the grabbing with nzbget and sort with sick and couch. I noticed with MCEbuddy, if I am running even a single TV stream (HD), it will buffer when MCEbuddy is doing comskip and such. Lesson was that either time it all, or put everything on different drives. 2gig per 30min for an HD stream just clugs the pipe on my mech (sata3) drives.

Just tested..3 streams, no problem. So you just have to watch for high utilization procs like rar.
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#8
Thank you guys for your help an insight. The PIs are all hardwired off a gigabit LAN. My and is a netgear nv+. I tried off loading sabnzbd, sick beard and couch potato to it but it was way to slow. Even downloading was insanely slow. I think the best option is to use separate hard drives and hold off on major file moves until late at night. Thanks again everyone.
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#9
have you bought and applied the mpeg2 license? you will need to buy one for each unique serial number, that will enable hardware decoding for mpeg2 files, which is what live u.s. tv comes in as.
http://www.raspberrypi.com/mpeg-2-license-key/
http://www.makeuseof.com/tag/how-to-add-...ia-centre/
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#10
Yeah I have licences for each PI. Thanks
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