On Fri, 25 May 2012 14:35:57 +0200 Sebastian Riemer <sebastian.riemer@xxxxxxxxxxxxxxxx> wrote: > Hi Neil, > > On 22/05/12 01:28, NeilBrown wrote: > > > > This should be fixed in linux 3.4 with commit 6b740b8d79252f13bcb7e5d3c1d > > > > I've tested the RAID 01 with kernel 3.4 and it isn't fixed. It is even > worse, because direct IO doesn't work any more on the raid1 device (with > kernel 3.2 it worked). What do you mean by "doesn't work"? Returns errors? crashes? hangs? kills you cat? It works for me. When I use 32K direct writes to a RAID1, both underlying RAID0 arrays see 64-sector writes. (when I do normal buffered writes I see 8-sector writes which seems odd, but clearly md/RAID1 is allowing large writes through) NeilBrown > > There are still 4k chunks which aren't merged in the raid0 devices below > (blkparse -i md100 -i md200 -i md300 | less). > Could you also check this on your setup, please? > > Cheers, > Sebastian > > > Btw. this is my test script: > > #!/bin/bash > if [ "`lsmod | grep brd`" == "" ]; then > modprobe brd rd_nr=4 rd_size=524288 > fi > mdadm -C /dev/md100 --force --assume-clean -n 2 -l raid0 /dev/ram0 /dev/ram1 > mdadm -C /dev/md200 --force --assume-clean -n 2 -l raid0 /dev/ram2 /dev/ram3 > blktrace /dev/md100 & > pid=$! > dd if=/dev/zero of=/dev/md100 bs=1M oflag=direct > kill -2 $pid > blktrace /dev/md200 & > pid=$! > dd if=/dev/zero of=/dev/md200 bs=1M oflag=direct > kill -2 $pid > mv md100* r0_only/ > mv md200* r0_only/ > > mdadm -C /dev/md300 --force --assume-clean -n 2 -l raid1 /dev/md100 > /dev/md200 > blktrace -d /dev/md100 -d /dev/md200 -d /dev/md300 -b 4096 & > pid=$! > # Kernel 3.4 doesn't support direct IO on the md300 device > dd if=/dev/zero of=/dev/md300 bs=1M > kill -2 $pid > -- > 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
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