Sometimes when booting off an Arch installation ISO (even recent kernel 4.16.8 & lvm2 2.02.177) LVM's pvscan takes 60-90 minutes. This is with large thin pools, which seems to have caused such delays for people in the past, with a fix being adding "--skip-mappings" in thin_check_options. This used to always happen when booting off an ISO, until I made a custom one with "--skip-mappings". With this, it's intermittent. Sometimes nearly instant, sometimes 45-90 minutes. This delay never happens when booting off an install on a drive. (I'm thinking there must be a cache that obviously doesn't exist on the ISO?) When there's a massive delay: root@archiso ~ # date && ps ax | grep scan Mon May 14 03:08:14 UTC 2018 717 ? S<Ls 0:00 /usr/bin/lvm pvscan --cache --activate ay 8:65 718 ? S<Ls 0:00 /usr/bin/lvm pvscan --cache --activate ay 8:19 719 ? S<Ls 0:00 /usr/bin/lvm pvscan --cache --activate ay 8:51 720 ? S<Ls 0:00 /usr/bin/lvm pvscan --cache --activate ay 8:115 721 ? S<Ls 0:00 /usr/bin/lvm pvscan --cache --activate ay 8:99 722 ? S<Ls 0:00 /usr/bin/lvm pvscan --cache --activate ay 8:68 724 ? S<Ls 0:00 /usr/bin/lvm pvscan --cache --activate ay 8:52 725 ? S<Ls 0:00 /usr/bin/lvm pvscan --cache --activate ay 8:49 727 ? S<s 0:00 /usr/bin/lvm pvscan --cache --activate ay 8:67 728 ? S<Ls 0:00 /usr/bin/lvm pvscan --cache --activate ay 8:66 731 ? S<Ls 0:00 /usr/bin/lvm pvscan --cache --activate ay 8:83 733 ? S<Ls 0:00 /usr/bin/lvm pvscan --cache --activate ay 8:50 748 ? S<Ls 0:00 /usr/bin/lvm pvscan --cache --activate ay 8:2 752 ? S<Ls 0:00 /usr/bin/lvm pvscan --cache --activate ay 8:1 753 ? S<Ls 0:00 /usr/bin/lvm pvscan --cache --activate ay 8:3 754 ? S<Ls 0:01 /usr/bin/lvm pvscan --cache --activate ay 8:4 755 ? S<Ls 0:00 /usr/bin/lvm pvscan --cache --activate ay 8:33 756 ? S<Ls 0:00 /usr/bin/lvm pvscan --cache --activate ay 8:36 757 ? S<Ls 0:00 /usr/bin/lvm pvscan --cache --activate ay 8:35 759 ? S<Ls 0:00 /usr/bin/lvm pvscan --cache --activate ay 8:34 768 ? S<Ls 0:01 /usr/bin/lvm pvscan --cache --activate ay 259:1 And iotop shows 0 bytes being read or written for most of it. Is Arch using pvscan incorrectly? Is it meant for a process to be ran for each device? Is concurrently running a pvscan for each devicepath causing lock contention? Should Arch be running one instance of pvscan without device major and minor block numbers? Here is Arch's "lvm2-pvscan@.service" ===== [Unit] Description=LVM2 PV scan on device %i Documentation=man:pvscan(8) DefaultDependencies=no StartLimitInterval=0 BindsTo=dev-block-%i.device Requires=lvm2-lvmetad.socket After=lvm2-lvmetad.socket lvm2-lvmetad.service Before=shutdown.target Conflicts=shutdown.target [Service] Type=oneshot RemainAfterExit=yes ExecStart=/usr/bin/lvm pvscan --cache --activate ay %i ExecStop=/usr/bin/lvm pvscan --cache %i _______________________________________________ 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/
