> Ana: > > You are making this way too hard for yourself > If you want to stop the queue but let the RAID system continue > processing the queue, then just sending I/O from whatever program you > are using to generate the load. This won't let you start up with a > partially unflushed queue, but if for whatever reason you need to > measure effects of pending I/Os and timing, then you can obtain a > reasonably good simulation by increasing the queue depth and repeating > the test. I didn't quite understood what you are saying. I need to stop the queue in order to see its growth. > > As for A way to get RAID (I assume software RAID, a la the md driver), > to get out of sync is to "remove" a disk drive. If you are afraid to > crack the case, then use a cheap USB enclosure for one of the disks and > then turn it off or unplug the USB connector. You can also "remove" a > disk by sending it a command to go into a self-test, perform a low-level > format, send a mode select to change the block size, there are lots of > ways if you think outside of the box. By doing this I wouldn't see its queue building up, would I? Basically I need to simulate a raid with disks of different speeds. Where a faster mirror would process its requests before the slower ones. For reads it processes more requests to keep the raid load balanced. But for writes I can't load balance, all have to write. The problem is that the faster is slowing down to meet the slower disk throughput. See the queue build up is key. Thanks, AP > > All of these "failure" scenarios will interact differently, just turning > a disk drive off creates a real failure, not a quasi-emulated more > graceful failure that may be easier for you to time and measure the > effects. > > Good luck. > > David @ santools.com > > > -- > 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 > -- 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
