Red Hat Bugzilla – Bug 1020297
Reduction of 2 legged mirror while the 3rd. leg is being synchronized breaks the mirror.
Last modified: 2016-07-19 06:29:52 EDT
Description of problem: When lvconvert -m-1 is executed on mirror which is not yet fully synchronized, log removal cause abort of conversion process. This can be observed in lvm2 internal test suite (make check_cluster T=lvconvert-mirror.sh): lvconvert-mirror.sh: line ~190 lvconvert -m-1 $vg/$lv1 "$dev2" If this conversion is execute just in time, convertion from the command above -m+1 is not yet fully synchronize, it will fail together with signs, there are still some mimagetmp volumes: metadata/lv_manip.c:696 Stack LV1:0[0] on LV LV1_mimagetmp_2:0 metadata/lv_manip.c:300 Adding LV1:0 as an user of LV1_mimagetmp_2 metadata/lv_manip.c:696 Stack LV1:0[1] on LV LV1_mimage_2:0 metadata/lv_manip.c:300 Adding LV1:0 as an user of LV1_mimage_2 metadata/lv_manip.c:696 Stack LV1_mimagetmp_2:0[0] on LV LV1_mimage_0:0 metadata/lv_manip.c:300 Adding LV1_mimagetmp_2:0 as an user of LV1_mimage_0 metadata/lv_manip.c:300 Adding LV1_mimagetmp_2:0 as an user of LV1_mlog locking/cluster_locking.c:428 Requesting backup of VG metadata for @PREFIX@vg format_text/archiver.c:226 WARNING: This metadata update is NOT backed up metadata/mirror.c:1102 Failed to initialize log device Version-Release number of selected component (if applicable): 2.02.103 How reproducible: Steps to Reproduce: 1. lvconvert -m+1 2. right after that lvconvert -m-1 while the first conversion is not fully done. 3. Actual results: Expected results: Additional info:
So the problem looks to be related to how the mirror evaluates it's still a mirror. If the mirror has just 2 legs - and I add 1 leg - which is slowly being synchronized, and while the synchronization is still in progress, I cut other the one of those in-sync legs - the mirror tries to demolish itself. This is catched by clvmd test which is missing the lock from log_lv, thus lvconvert attemt to deactivate this LV (which has no lock) fails - that's probably the reason for the weird sequence in the lvm2 code: (lib/metadata/mirror.c - line ~300) /* If the LV is active, deactivate it first. */ if (lv_is_active(log_lv)) { (void) deactivate_lv(cmd, log_lv); /* * FIXME: workaround to fail early * Ensure that log is really deactivated because deactivate_lv * on cluster do not fail if there is log_lv with different UUID. */ if (lv_is_active(log_lv)) { log_error("Aborting. Unable to deactivate mirror log."); goto revert_new_lv; } Which is fails in cluster since without lock no deactivation is called - so lv will remain active and the second test fails. This is sign of multiple bugs here - mirror needs to be deactivated through it master LV - and it should never go to the subdevices. And also we have here the problem with detection what is and what is not a mirror. So if the mirror is being upscaled, and the removal of the leg would cause device to be no longer mirrored - seems we have multiple choices - let it go - mirror will catchup later to be a mirror? abort instantly - and warn user he needs to wait till mirror has synced its legs? Here is short 'test-suite' code to demonstrate the problem: -- . lib/test aux prepare_pvs 4 vgcreate -s 32k $vg $(cat DEVICES) # "remove from original mirror (the original is still mirror)" lvcreate -aey -l10 --type mirror -m1 -n $lv1 $vg "$dev1" "$dev2" "$dev3" aux delay_dev "$dev4" 0 100 lvconvert -m+1 -b $vg/$lv1 "$dev4" lvs -a -o+devices $vg lvconvert -m-1 $vg/$lv1 "$dev2" lvs -a -o+devices $vg vgremove -ff $vg --
This bug appears to have been reported against 'rawhide' during the Fedora 22 development cycle. Changing version to '22'. More information and reason for this action is here: https://fedoraproject.org/wiki/Fedora_Program_Management/HouseKeeping/Fedora22
Fedora 22 changed to end-of-life (EOL) status on 2016-07-19. Fedora 22 is no longer maintained, which means that it will not receive any further security or bug fix updates. As a result we are closing this bug. If you can reproduce this bug against a currently maintained version of Fedora please feel free to reopen this bug against that version. If you are unable to reopen this bug, please file a new report against the current release. If you experience problems, please add a comment to this bug. Thank you for reporting this bug and we are sorry it could not be fixed.