On Tue, 14 Jun 2022 14:14:42 +0500 Roman Mamedov <rm@xxxxxxxxxxx> wrote: > Hello, > > I upgraded mdadm to 4.2 to get the bitmap support in IMSM. > > I run: "mdadm --update-subarray=0 -U bitmap /dev/md127" > However the array details stay the same, with "Consistency Policy : resync". > No error is reported, and nothing in dmesg. > > How to actually use it? > Hi Roman, There is a bug in mdadm (will be fixed soon) which allows you to update subarray on active volume. Update is successful but mdmon will overwrite it. To enable bitmap, you need to stop member array first: # mdadm -S /dev/md126 then run update command: # mdadm --update-subarray=0 -U bitmap /dev/md127 mdadm will set bitmap in metadata: #mdadm -E /dev/md127 At the end, start member volume: # mdadm -As Now, you can verify array details: # mdadm -D /dev/md126. Hope it helps, Mariusz > Thanks > > > # mdadm --detail /dev/md127 > /dev/md127: > Version : imsm > Raid Level : container > Total Devices : 4 > > Working Devices : 4 > > > UUID : d07837ca:804cf5e3:01c52352:f64b0524 > Member Arrays : /dev/md/Volume0 > > Number Major Minor RaidDevice > > - 8 32 - /dev/sdc > - 8 0 - /dev/sda > - 8 48 - /dev/sdd > - 8 16 - /dev/sdb > > # mdadm --detail /dev/md126 > /dev/md126: > Container : /dev/md/imsm0, member 0 > Raid Level : raid10 > Array Size : 1953519616 (1863.02 GiB 2000.40 GB) > Used Dev Size : 976759808 (931.51 GiB 1000.20 GB) > Raid Devices : 4 > Total Devices : 4 > > State : active > Active Devices : 4 > Working Devices : 4 > Failed Devices : 0 > > Layout : near=2 > Chunk Size : 64K > > Consistency Policy : resync > > > UUID : xxx > Number Major Minor RaidDevice State > 3 8 0 0 active sync set-A /dev/sda > 2 8 16 1 active sync set-B /dev/sdb > 1 8 32 2 active sync set-A /dev/sdc > 0 8 48 3 active sync set-B /dev/sdd > > # mdadm --update-subarray=0 -U bitmap /dev/md127 > > # mdadm --detail /dev/md127 > /dev/md127: > Version : imsm > Raid Level : container > Total Devices : 4 > > Working Devices : 4 > > > UUID : d07837ca:804cf5e3:01c52352:f64b0524 > Member Arrays : /dev/md/Volume0 > > Number Major Minor RaidDevice > > - 8 32 - /dev/sdc > - 8 0 - /dev/sda > - 8 48 - /dev/sdd > - 8 16 - /dev/sdb > > # mdadm --detail /dev/md126 > /dev/md126: > Container : /dev/md/imsm0, member 0 > Raid Level : raid10 > Array Size : 1953519616 (1863.02 GiB 2000.40 GB) > Used Dev Size : 976759808 (931.51 GiB 1000.20 GB) > Raid Devices : 4 > Total Devices : 4 > > State : active > Active Devices : 4 > Working Devices : 4 > Failed Devices : 0 > > Layout : near=2 > Chunk Size : 64K > > Consistency Policy : resync > > > UUID : xxx > Number Major Minor RaidDevice State > 3 8 0 0 active sync set-A /dev/sda > 2 8 16 1 active sync set-B /dev/sdb > 1 8 32 2 active sync set-A /dev/sdc > 0 8 48 3 active sync set-B /dev/sdd > > >
