On Fri, Jan 18 2013 at 5:19am -0500, Daniel Browning <db@xxxxxxxxx> wrote: > Why do I get the following error, and what should I do about it? When I > create a raid0 md with a non-power-of-two chunk size (e.g. 1152K instead of > 512K), then create a thinly-provisioned volume that is over 256 GiB, I get > the following dmesg error when I try to create a file system on it: > > "make_request bug: can't convert block across chunks or bigger than 1152k 4384 127" > > This bubbles up to mkfs.xfs as > > "libxfs_device_zero write failed: Input/output error" > > What I find interesting is that it seems to require all three conditions > (chunk size, thin-p, and >256 GiB) in order to fail. Without those, it seems > to work fine: > > * Power-of-two chunk (e.g. 512K), thin-p vol, >256 GiB? Works. > * Non-power-of-two chunk (e.g. 1152K), thin-p vol, <256 GiB? Works. > * Non-power-of-two chunk (e.g. 1152K), regular vol, >256 GiB? Works. > * Non-power-of-two chunk (e.g. 1152K), thin-p vol, >256 GiB? FAIL. > > Attached is a self-contained test case to reproduce the error, version > numbers, and an strace. Thank you in advance, > -- > Daniel Browning > Kavod Technologies > > Appendix A. Self-contained reproduce script > =========================================================== > dd if=/dev/zero of=loop0.img bs=1G count=150; losetup /dev/loop0 loop0.img > dd if=/dev/zero of=loop1.img bs=1G count=150; losetup /dev/loop1 loop1.img > mdadm --create /dev/md99 --verbose --level=0 --raid-devices=2 \ > --chunk=1152K /dev/loop0 /dev/loop1 > pvcreate /dev/md99 > vgcreate test_vg /dev/md99 > lvcreate --size 257G --type thin-pool --thinpool test_thin_pool test_vg > lvcreate --virtualsize 257G --thin test_vg/test_thin_pool --name test_lv > mkfs.xfs /dev/test_vg/test_lv > > # That is where the error occurs. Next is cleanup. > lvremove -f /dev/test_vg/test_lv > lvremove -f /dev/mapper/test_vg-test_thin_pool > vgremove -f test_vg > pvremove /dev/md99 > mdadm --stop /dev/md99 > mdadm --zero-superblock /dev/loop0 /dev/loop1 > losetup -d /dev/loop0 /dev/loop1 > rm loop*.img Limits of the raid0 device (/dev/md99): cat /sys/block/md99/queue/minimum_io_size 1179648 cat /sys/block/md99/queue/optimal_io_size 2359296 Limits of the thin-pool device (/dev/test_vg/test_thin_pool): cat /sys/block/dm-9/queue/minimum_io_size 512 cat /sys/block/dm-9/queue/optimal_io_size 262144 Limits of the thin-device device (/dev/test_vg/test_lv): cat /sys/block/dm-10/queue/minimum_io_size 512 cat /sys/block/dm-10/queue/optimal_io_size 262144 I notice that lvcreate is not using a thin-pool chunksize that matches the raid0's chunksize (just uses the lvm2 default of 256K). Switching the thin-pool lvcreate to use --chunksize 1152K at least enables me to format the filesystem. And both the thin-pool and thin device have an optimal_io_size that matches the chunk_size of the underlying raid volume: cat /sys/block/dm-9/queue/optimal_io_size 1179648 cat /sys/block/dm-10/queue/optimal_io_size 1179648 I'm still investigating the limits issue when --chunksize 1152K isn't used for the thin-pool lvcreate. -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
