On Fri, Nov 21, 2003 at 09:52:18PM -0600, Callum Lerwick wrote: > Totally completely unnecessary. Even with a reasonably high bit rate > MPEG4, 2500kbit, you're at a little over 300k/sec, which is WAY below > what even my old SLOW ASS Fujitsu UDMA33 drive was capable of, 10mb/sec. > Hell, the original 286 era PIO mode0 IDE could do 3mb/sec. These speed benchmarks have no real meaning. The speed obtained with the actual application is what is important! I meant to suggest using RAID software or hardware for a video server which may have several TV tuner cards recording video streams and several output streams to client TVs. The actuator of a single hard drive might trash violently, if the streams are several cylinders apart. Also, consider that the sustained read/write rate of any modern disk drive on the inner cylinders is about half what it is on the outer cylinders. The overhead of the software handling the streams should be considered as well. > Disk bandwidth is nowhere even near being a bottleneck. Even if you > start playing and recording several streams at a time. With multiple > clients the network bandwidth is going to nail you first. Viva > compression! Never underestimate disk bandwidth requirements and multiple layers of overhead. Re-mapped sectors on the disk can cause performance problems as well. Disk performance problems can occur in multiple levels in both hardware and software, a few of which have been mentioned above. If there's not enough RAM, one could also have some plain old disk thrashing as well. Finally, I didn't want to argue about the performance justification of RAID for this application. I was just curious about whether anyone had used RAID (software or hardware) for this application. If you could get a cheap UDMA33 hard drive or a cheap SCSI RAID setup for this application, which would you use? Sincerely, Ken Fuchs <kfuchs at winternet.com> _______________________________________________ TCLUG Mailing List - Minneapolis/St. Paul, Minnesota http://www.mn-linux.org tclug-list at mn-linux.org https://mailman.real-time.com/mailman/listinfo/tclug-list