0007971: LVM breaks SSD TRIM discard

Hi,<br /> <br /> i am trying to install SSD disks with software mirroring for fault tolerance.<br /> <br /> This guide, Chapter 22.1 explains why md-raid1 is a bad idea, and to use LVM dm-mirror instead:<br /> <a href="https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/7/html/Storage_Administration_Guide/ch-ssd.html">https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/7/html/Storage_Administration_Guide/ch-ssd.html</a> [<a href="https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/7/html/Storage_Administration_Guide/ch-ssd.html" target="_blank">^</a>]<br /> <br /> I configured "issue_discards = 1" in /etc/lvm/lvm.conf.<br /> I mounted the filesystems with discard option.<br /> I installed my system with LVM dm-mirror, and LVM dm-mirror seems to break discards.<br /> <br /> fstrim works on non-LVM partitions, but not on LVM partitions, so HW is o.k.<br /> # fstrim /boot<br /> # fstrim /var<br /> fstrim: /var: FITRIM ioctl failed: Operation not supported<br /> <br /> <br /> #mount<br /> /dev/mapper/centos-root on / type ext4 (rw,relatime,discard,data=ordered)<br /> /dev/sda1 on /boot type ext4 (rw,relatime,discard,data=ordered)<br /> /dev/mapper/centos-var on /var type ext4 (rw,noatime,discard,data=ordered)<br /> <br /> #lvs -a:<br /> LV VG Attr LSize Pool Origin Data% Move Log Cpy%Sync Convert<br /> root centos rwi-aor--- 31.25g 100.00<br /> [root_rimage_0] centos iwi-aor--- 31.25g<br /> [root_rimage_1] centos iwi-aor--- 31.25g<br /> [root_rmeta_0] centos ewi-aor--- 4.00m<br /> [root_rmeta_1] centos ewi-aor--- 4.00m<br /> var centos rwi-aor--- 117.19g 100.00<br /> [var_rimage_0] centos iwi-aor--- 117.19g<br /> [var_rimage_1] centos iwi-aor--- 117.19g<br /> [var_rmeta_0] centos ewi-aor--- 4.00m<br /> [var_rmeta_1] centos ewi-aor--- 4.00m<br /> <br /> <br /> # lsblk -Di<br /> NAME DISC-ALN DISC-GRAN DISC-MAX DISC-ZERO<br /> sda 0 512B 2G 0<br /> |-sda1 0 512B 2G 0<br /> `-sda2 0 512B 2G 0<br /> |-centos-root_rmeta_0 0 512B 2G 0<br /> | `-centos-root 0 512B 2G 0<br /> |-centos-root_rimage_0 0 512B 2G 0<br /> | `-centos-root 0 512B 2G 0<br /> |-centos-var_rmeta_0 0 512B 2G 0<br /> | `-centos-var 0 512B 2G 0<br /> `-centos-var_rimage_0 0 512B 2G 0<br /> `-centos-var 0 512B 2G 0<br /> sdb 0 512B 2G 0<br /> |-sdb1 0 512B 2G 0<br /> `-sdb2 0 512B 2G 0<br /> |-centos-root_rmeta_1 0 512B 2G 0<br /> | `-centos-root 0 512B 2G 0<br /> |-centos-root_rimage_1 0 512B 2G 0<br /> | `-centos-root 0 512B 2G 0<br /> |-centos-var_rmeta_1 0 512B 2G 0<br /> | `-centos-var 0 512B 2G 0<br /> `-centos-var_rimage_1 0 512B 2G 0<br /> `-centos-var 0 512B 2G 0<br /> sdc 0 0B 0B 0<br /> |-sdc1 0 0B 0B 0<br /> `-sdc2 0 0B 0B 0<br /> sdd 0 0B 0B 0<br /> |-sdd1 0 0B 0B 0<br /> `-sdd2 0 0B 0B 0<br /> sr0 0 0B 0B 0