On Sun, May 13 2018 at 8:47pm -0400, Pankaj Agarwal <pankaj@releasemanager.in> wrote: > Hi, > How do i set the nr_request value for LV's as it's not writable like other > drives on a linux system. > LV's are set as dm-0 and dm-1 on my system. > #cat /sys/block/dm-0/queue/nr_requests > 128 > # echo 256 > /sys/block/dm-0/queue/nr_requests > -bash: echo: write error: Invalid argument In the block layer, bio-based devices cannot have their nr_requests changed, see: block/blk-sysfs.c:queue_requests_store() So any bio-based DM device (e.g. linear target) won't be allowed to change nr_requests. The only way to change this would be from the bottom up: 1) change the underlying request-based device(s) (e.g. /dev/sda) 2) dmsetup suspend + dmsetup resume any bio-based DM device(s) that are stacked ontop of the request-based device(s) you changed in 1) -- this will restack the queue_limits from the bottom up; so the DM device will then reflect the underlying devices' limits. Mike _______________________________________________ linux-lvm mailing list linux-lvm@redhat.com https://www.redhat.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
