On Mon, Dec 06, 2004 at 07:11:14PM -0500, Taylor Jacob wrote: > Maybe I am missing somthing here.. But how in the world does this problem > exist? > Raw TS from ATSC is 19.39 megabit.. 3 of them would be ~60 megabit ~= 7.5 > megabytes a second.. Even a rotten 5400 rpm drive can sustain writes over > that.. > > Taylor
A drive can sustain that at times, but not always. If you are writing a single file and the head of the driver does not have to move except where it's writing then it's easy to get that speed. Once you add 3 streams being saved to different possitions on the disk you loose a lot of throughput in the head of the drive moving. If you're reading a show from disk you're possibly moving the head quite a ways. If you're accessing other data randomly from the disk for whatever reason, .. you get the point. So writing data is a problem. -- And it's not always the disk. What I personally see is on AMD XP mainboards, you sometimes can max out the system bus. Each tuner card dumps a 45mb/s stream (This can be fixed in the driver, to only send a single stream, instead of the entire ATSC stream for a channel, so 4.5mb-19.4mb. Some quick math is 150mb/s of data from the 3 tuner cards, another 60mb being written to disk, if you're watching a show that's another 20+20mb. In the end it starts to add up, and I have had dozens problems that I can track back to maxing out my system bus (And from what I can see, AGP often gets preference to pci, which is another problem). I have a raid 0 with 5 drives and can write about 60MB/s. I still see many buffer problems, and disk speed is not the problem. Food for though. --Brandon
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