Hi, Up until now I was having 8 mdadm RAID6 arrays which are sharing the same 6 different sized devices with 1TB partitions, like: md0: sda1 sdb1 sdc1... md1: sda2 sdb2 sdc2... . . . md7: sda8 sdb8 sde5 sdd7... It was set up like this so I can efficiently use the space from different sized disks. Since lvmraid has support for integrity on lvmraid devices, I backed up everything and trying to recreate a similar structure with lvmraid and integrity enabled. In the past when multiple mdadm arrays needed to resync, they would wait for each other to finish before, because mdadm detected those arrays shared the same disks. Now when I was trying to recreate the arrays I realized that the initial lvmraid syncs doesn't wait for each other. This means I can't recreate the whole structure in one go as it would trash the IO on these HDDs. I don't know if this is on purpose, because I haven't tried lvmraid before, but I know lvmraid uses md under the hood, and I'm thinking that this might be a bug, because the md code in kernel can't detect the underlying devices through the integrity layer. But I think it might worth to get fixed, as even with just 3 raid6 lvmraids and sync speed reduced to 10M by dev.raid.speed_limit_max sysctl I get a pretty high load: [root@hp ~] 2021-04-10 02:07:38 # lvs LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert root pve rwi-aor--- 29,25g 100,00 md0 raid6-0 rwi-a-r--- <3,61t 40,54 md1 raid6-1 rwi-a-r--- <2,71t 8,54 md2 raid6-2 rwi-a-r--- <3,61t 1,01 [root@hp ~] 2021-04-10 02:30:46 # pvs -S vg_name=raid6-0 PV VG Fmt Attr PSize PFree /dev/sda3 raid6-0 lvm2 a-- 931,50g 4,00m /dev/sdb1 raid6-0 lvm2 a-- 931,50g 4,00m /dev/sdd6 raid6-0 lvm2 a-- 931,50g 4,00m /dev/sde6 raid6-0 lvm2 a-- 931,50g 4,00m /dev/sdf1 raid6-0 lvm2 a-- 931,50g 4,00m /dev/sdg4 raid6-0 lvm2 a-- 931,50g 4,00m [root@hp ~] 2021-04-10 02:35:39 # uptime 02:35:40 up 1 day, 29 min, 4 users, load average: 138,20, 126,23, 135,60 Although this is just due to the insane amount of integrity kworker processes, and the system is pretty usable, I think it would be much nicer to only have 1 sync running on the same physical device at a time. _______________________________________________ linux-lvm mailing list linux-lvm@xxxxxxxxxx https://listman.redhat.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
