I created a new LVM volume group and a linear volume on it. After converting it to a raid1 volume, the kernel won't start to sync it. I have observed this behavior on both kernels 4.2.1 and 4.0.8; the pasted output is from 4.2.1. FWIW, this is the same computer as in Bug 100491, another dm-raid1 related bug. However I created a completely new volume group and a new logical volume, so I don't know how related these are. What I did: 1. pvcreate /dev/sdb5 /dev/sdb6 /dev/sdc2 2. vgcreate vg /dev/sdb5 /dev/sdb6 /dev/sdc2 3. lvcreate -n root -L 900G /dev/sdb5 [... steps to set up a dm-crypt mapping on /dev/mapper/vg-root, create a filesystem] 4. lvconvert -m1 vg/root /dev/sdc2 Now, lvconvert succeeds and I get this on dmesg: ------------------------------------------------------------ [ 3505.979470] device-mapper: raid: Superblocks created for new array [ 3505.980026] md/raid1:mdX: not clean -- starting background reconstruction [ 3505.980028] md/raid1:mdX: active with 2 out of 2 mirrors [ 3505.980030] Choosing daemon_sleep default (5 sec) [ 3505.980050] created bitmap (900 pages) for device mdX [ 3505.996918] mdX: bitmap file is out of date, doing full recovery [ 3512.853779] mdX: bitmap initialized from disk: read 57 pages, set 1843200 of 1843200 bits ------------------------------------------------------------ However, nothing else happens. Specifically, there is no disk activity on /dev/sdc2. In lvs output, Cpy%Sync is perpetually stuck on 0.00. ------------------------------------------------------------ # lvs -o +seg_pe_ranges --all LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert PE Ranges backup rootvg -wi-ao---- 800.00g /dev/sdc4:0-118989 backup rootvg -wi-ao---- 800.00g /dev/sdc3:18024-103833 root rootvg -wi-ao---- 1.32t /dev/sda2:0-345129 root vg rwi-aor--- 900.00g 0.00 root_rimage_0:0-230399 root_rimage_1:0-230399 [root_rimage_0] vg Iwi-aor--- 900.00g /dev/sdb5:0-230399 [root_rimage_1] vg Iwi-aor--- 900.00g /dev/sdc2:1-230400 [root_rmeta_0] vg ewi-aor--- 4.00m /dev/sdb5:230400-230400 [root_rmeta_1] vg ewi-aor--- 4.00m /dev/sdc2:0-0 ------------------------------------------------------------ ------------------------------------------------------------ # vgcreate --version LVM version: 2.02.127(2) (2015-08-10) Library version: 1.02.104 (2015-08-10) Driver version: 4.33.0 ------------------------------------------------------------