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
Appendix B. Versions
===========================================================
Distro: CentOS 6.3
Kernel: 3.7.2-1.el6xen.x86_64 from dev.crc.id.au
LVM version: 2.02.99(2)-git (2012-10-22)
Library version: 1.02.78-git (2012-10-22)
Driver version: 4.23.0
XFS userspace: xfsprogs-3.1.1-7.el6.x86_64
Appendix C. strace of mkfs.xfs
===========================================================
See http://pastebin.com/raw.php?i=hLLm0jVC for the full strace. An excerpt:
lseek(4, 137975840768, SEEK_SET) = 137975840768
write(4, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 262144) = 262144
write(4, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 262144) = 262144
write(4, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 262144) = -1 EIO (Input/output error)
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