Question about dual tuners with PATA

[han0522]

Alright, I've done some searching and didn't find a thread related to this.

I've been a happy SageTV user for 2 years now. I'm considering adding a 150 MCE (to a 250MCE) to bring my box up to 2 tuners. Right now it has one 200 GB PATA 7200 Seagate hdd. I've no problems right now (well, occasionally there's some stuttering, but I find that is when something is stealing CPU resources; so just close whatever it is down and go about my business). However, my question is, if I were to add another tuner and both tuners were recording at the same time, would I see noticable stuttering/dropped frames, whatever, in the video because they are both recording to the same hdd? What if I were to add an additional 200 GB hdd? Is there a way to dedicate one tuner to one specific hdd?

Thanks for any help!
-Chris

[stanger89]

You shouldn't I've got 3 tuners on a similar HDD, with no issues.

[jominor]

Originally Posted by han0522

Alright, I've done some searching and didn't find a thread related to this.

I've been a happy SageTV user for 2 years now. I'm considering adding a 150 MCE (to a 250MCE) to bring my box up to 2 tuners. Right now it has one 200 GB PATA 7200 Seagate hdd. I've no problems right now (well, occasionally there's some stuttering, but I find that is when something is stealing CPU resources; so just close whatever it is down and go about my business). However, my question is, if I were to add another tuner and both tuners were recording at the same time, would I see noticable stuttering/dropped frames, whatever, in the video because they are both recording to the same hdd? What if I were to add an additional 200 GB hdd? Is there a way to dedicate one tuner to one specific hdd?

Thanks for any help!
-Chris

I've got 3 tuners(2 PCI, 1 USB2) and 8 USB2 drives. I don't think you'll see any problems.

[GKusnick]

Do the math. A recording quality of 3 GB/hour works out to 0.83 MB/s. Typical sustained transfer rates for today's drives are around 40 MB/s minimum, so even with five tuners recording at once you'd be using maybe a tenth of your drive's bandwidth.

[src666]

Originally Posted by GKusnick

Do the math. A recording quality of 3 GB/hour works out to 0.83 MB/s. Typical sustained transfer rates for today's drives are around 40 MB/s minimum, so even with five tuners recording at once you'd be using maybe a tenth of your drive's bandwidth.

True, although the 40MB/s is usually the sustained transfer rate for sequential data. Dealing with the random access requirements of writing/reading multiple files, along with their supporting data on the partition drops the throughput considerably. But in the real world you are usually going to be CPU bound before you are I/O bound.

[blade]

Originally Posted by src666

But in the real world you are usually going to be CPU bound before you are I/O bound.

I doubt you'd become CPU bound using hardware encoders. My Sage server has a celeron 366 and uses next to no CPU time when capturing 4 shows, streaming all 4 to be processed by comskip, and streaming another to the client.

[src666]

Originally Posted by blade

I doubt you'd become CPU bound using hardware encoders. My Sage server has a celeron 366 and uses next to no CPU time when capturing 4 shows, streaming all 4 to be processed by comskip, and streaming another to the client.

Good point. But add an MVP client or two and see what happens

[Opus4]

Originally Posted by src666

But add an MVP client or two and see what happens

Unless you are transcoding the video, it still shouldn't use a lot of cpu power. The MVP decodes mpeg2 video itself and draws its own UI. For mpeg2 playback, it is essentially just another stream.

- Andy

[src666]

Originally Posted by Opus4

Unless you are transcoding the video, it still shouldn't use a lot of cpu power. The MVP decodes mpeg2 video itself and draws its own UI. For mpeg2 playback, it is essentially just another stream.

- Andy

Whups, wrong again I guess. I keep forgetting that the MVP code moved the UI to the client.