> > Not transcoding at the same time, just the standard commercial > > flagging. The drive light is constantly on. CPU is pretty busy > > (3GHz) reaching 180% when simultaneously flagging 2 videos. > > > > The database in in the / partition of the array, and the videos are in > > the /home partition on it. No idea why the array is so busy. > > > If they're both on the array, then that's the problem. The partitioning > doesn't make difference to the issue - the drive heads are having to > seek frantically between reading the data file and writing the database. You are perfectly correct that having the database and the video files on the same array presents a very significant bottleneck, but I think something else must be going on, as well. If the CPU were having to wait for drive seeks, then the CPU utilization would never be that high. What's more, while I am not intimately familiar with MythTV's database structure, I don't think database writes are done very much. Typically, in such applications, one only marks the audio / video transition points, where the video fades to black and the audio squelches and then again when a black transitions to live video. The rest of time should ordinarily be spent entirely in memory (other than reading the video file, of course), analyzing the video data to search for such transitions and decide whether the transition in question is the entry or exit point for a group of commercials. I would expect a write to the database would only occur after examining several minutes worth of video data - probably several seconds worth of reading video. I cannot say for certain, but I suspect he might see significant performance gains by increasing the size of his memory and perhaps his swap partition, as well. He also might do well to adjust the priority of the threads handling the commercial flagging. He hasn't mentioned what his actual drive performance is, but his main complaint seems to me not to be drive system performance but CPU loading. -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
