Hi everyone, I have a problem with data corruption using devmapper. I've done some work tracking it down, and hopefully you folks can point me further in the right direction. The kernel I'm using is 2.6.21-1.3228.fc7 (i.e. Fedora 7). LVM2 is lvm2-2.02.24-1.fc7. The dmsetup and libdevmapper is device-mapper-1.02.17-7.fc7. The original setup that showed the problem is this: Starting with two 500GB SATA drives (interface card uses a Silicon 3124 chipset), /dev/sdd and /dev/sde. I partitioned each into two 250GB chunks (250*1000*1000*1000, not 250*1024*1024*1024), and set up two RAID 1 sets such that /dev/md0 is /dev/sdd1+/dev/sde1 and /dev/md2 is /dev/sdd2+/dev/sde2. I then created a volume group ("storage") on top of /dev/md0 and /dev/md1. Finally, I allocated two logical volumes on top of that: "one" is -L300GB and "two" is -L100GB. mke2fs -j -m0 on /dev/storage/one and /dev/storage/two, and it would seem everything was fine, but after copying data to the two volumes, they would fail a fsck in pretty dramatic fashion (dozens of errors indicating pretty severe filesystem corruption). I'll skip all the steps I tried when reducing this down to a simple reproducible test case, but the end result is this: 1) Take a 500GB disk (as before, it's SATA plugged into a card using the sata_sil24 driver) 2) echo "0 482344960 linear 8:32 0" | dmsetup create one echo "0 209715200 linear 8:32 482345000" | dmsetup create two 3) mke2fs -j -m0 /dev/mapper/one mke2fs -j -m0 /dev/mapper/two mount /dev/mapper/one /one mount /dev/mapper/two /two 4) cd /one ; \ for i in `seq 0 3`; do dd if=/dev/zero bs=4K count=1M of=$i; done ; \ cd ; \ umount /one cd /two ; \ for i in `seq 0 3`; do dd if=/dev/zero bs=4K count=1M of=$i; done ; \ cd ; \ umount /two 5) fsck -f /dev/mapper/one fsck -f /dev/mapper/two Both filesystems return many errors on fsck. This is very repeatable. Note that this simplified reproduction case uses only the device mapper: RAID is not involved, nor is LVM. "dmsetup table" says: two: 0 209715200 linear 8:32 482345000 one: 0 482344960 linear 8:32 0 Just to be sure, I have run memtest86+ on the machine and badblocks on the disk. Both came up clean. Partitioning the disk and mke2fs-ing the partitions directly (i.e. no device-mapper), works fine. It's only when using the device-mapper does the corruption happen. There is nothing of interest logged in /var/log/messages or dmesg (I see the usual messages around 'mount', but that's it). Any suggestions? David -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel