Justin Piszcz wrote: > Using 4 raptor 150s: > > Without the tweaks, I get 111MB/s write and 87MB/s read. > With the tweaks, 195MB/s write and 211MB/s read. > > Using kernel 2.6.19.1. > > Without the tweaks and with the tweaks: > > # Stripe tests: > echo 8192 > /sys/block/md3/md/stripe_cache_size > > # DD TESTS [WRITE] > > DEFAULT: (512K) > $ dd if=/dev/zero of=10gb.no.optimizations.out bs=1M count=10240 > 10240+0 records in > 10240+0 records out > 10737418240 bytes (11 GB) copied, 96.6988 seconds, 111 MB/s [] > 8192K READ AHEAD > $ dd if=10gb.16384k.stripe.out of=/dev/null bs=1M > 10240+0 records in > 10240+0 records out > 10737418240 bytes (11 GB) copied, 64.9454 seconds, 165 MB/s What exactly are you measuring? Linear read/write, like copying one device to another (or to /dev/null), in large chunks? I don't think it's an interesting test. Hint: how many times a day you plan to perform such a copy? (By the way, for a copy of one block device to another, try using O_DIRECT, with two dd processes doing the copy - one reading, and another writing - this way, you'll get best results without huge affect on other things running on the system. Like this: dd if=/dev/onedev bs=1M iflag=direct | dd of=/dev/twodev bs=1M oflag=direct ) /mjt - 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
