On Sun, Nov 18, 2007 at 08:49:44PM +0000, pg_mh@xxxxxxxxxxxxxxxx wrote: > >>> On Sun, 18 Nov 2007 21:06:42 +0100, Bernd Schubert > >>> <bernd-schubert@xxxxxx> said: > > bernd-schubert> Hi, on raid-initialization or later on a re-sync > bernd-schubert> our systems become unresponsive. [ ... ] Also, > bernd-schubert> the higher the stripe cache size, the higher the > bernd-schubert> probability the system will go into this state. > > Is either point surprising? On a system booted over network, so without anything accessing the raid devices IHMO yes. > > [ ... ] > > bernd-schubert> Any ideas? > > Well, the default Linux storage subsystem parameters are set > usually for high throughput, not low latency. Anyhow, there is I don't speak about low latency, but latency of at least 24h is a bit high, isn't it? Linux is a multi-tasking system, even with high load it has to respond to keyboard input, especially when there are 8 CPUs with 4 of them in idle state (almost 4 used for sync processes). > another interesting point, which is how many disks in that RAID6 > array? What is the system bus and host adapter to the disk bus? 6 x Infortrend A16U-G2430 (hardware raid 6) on 3 dual-channel LSI22320 HBAs in U320 mode, so eventually we have raid66. Since linux-raid is presently not multi-threaded the the CPU would limit raid6 write performance to 200MB/s. Since we do have 8 CPUs, we have made 3 partions of each A16U-G2430, so in the end we have 3 x software-raid6. I know this is a high end configuration, but no latency critical component is at any limit, 4 CPUs are idling, PCI-X busses are far away from being saturated. Cheers, Bernd - 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
