Omer Frenkel has posted comments on this change.
Change subject: core: prevent split brain caused by fence commands
......................................................................
Patch Set 3:
(5 comments)
....................................................
File
backend/manager/modules/bll/src/main/java/org/ovirt/engine/core/bll/RestartVdsCommand.java
Line 30: import org.ovirt.engine.core.compat.Guid;
Line 31: import org.ovirt.engine.core.utils.lock.EngineLock;
Line 32:
Line 33: /**
Line 34: * Send a Stop followed bt Start action to a power control device.
typo 'by'
Line 35: *
Line 36: * This command should be run exclusively on a host for it is assuming
that when
Line 37: * a host is down it can mark all VMs as DOWN and start them on other
host.
Line 38: * 2 parallel action like that on the same server can lead to a race
where
Line 39: * the 1st flow end by starting VMs and the 2nd flow marking them as
down and
Line 40: * starting another instance of VMs on other hosts, leading to
split-brain where
Line 41: * 2 exact instances of VMs running in 2 different hosts and writing
to the same disk.
Line 42: *
Line 43: * In order to make this flow distinct the child commands, Start,
FenceManually and Start
typo 'stop' before FenceManually
Line 44: * are under the same lock as the parent, preventing other Restart,
Start,Stop,FenceVdsManually to interleave.
Line 45: *
Line 46: * @see FenceVdsBaseCommand#restartVdsVms() The critical section
restaring the VMs
Line 47: */
Line 133: makeLockingPair(VDS_FENCE,
SAME_ACTION_ON_ENTITY_ALREADY_IN_PROGRESS));
Line 134: }
Line 135:
Line 136: @Override
Line 137: protected EngineLock getLock() {
not sure why you need this override? this is done in commandBase, there is no
reason for the commandLock to be null, no?
Line 138: if (commandLock == null) {
Line 139: commandLock = new EngineLock(getExclusiveLocks(), null);
Line 140: }
Line 141: return commandLock;
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File
backend/manager/modules/bll/src/main/java/org/ovirt/engine/core/bll/storage/FenceVdsManualyCommand.java
Line 50: private final VDS _problematicVds;
Line 51:
Line 52: /**
Line 53: * Constructor for command creation when compensation is applied
on startup
Line 54: *
please remove white space
Line 55: * @param commandId
Line 56: */
Line 57: protected FenceVdsManualyCommand(Guid commandId) {
Line 58: super(commandId);
....................................................
File backend/manager/modules/dal/src/main/resources/bundles/AppErrors.properties
Line 1057: SCHEDULING_ALL_HOSTS_FILTERED_OUT=Cannot ${action} ${type}. There is
no host that satisfies current scheduling constraints. See bellow for details:
Line 1058: SCHEDULING_HOST_FILTERED_REASON=The host ${hostName} did not satisfy
${filterType} filter ${filterName}.
Line 1059: VAR__FILTERTYPE__EXTERNAL=$filterType external
Line 1060: VAR__FILTERTYPE__INTERNAL=$filterType internal
Line 1061: SAME_ACTION_ON_ENTITY_ALREADY_IN_PROGRESS=Same action, ${action}, is
already in progress.
not must, but maybe it would have been better to do a fencing specific message
here so it would give meaningful info to the user, something like:
"Cannot run power management action on host since ${action} is already in
progress."
--
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Gerrit-MessageType: comment
Gerrit-Change-Id: Iaf021010188e3c3662fbf8a057da4c58f2600c02
Gerrit-PatchSet: 3
Gerrit-Project: ovirt-engine
Gerrit-Branch: master
Gerrit-Owner: Roy Golan <rgo...@redhat.com>
Gerrit-Reviewer: Eli Mesika <emes...@redhat.com>
Gerrit-Reviewer: Martin Peřina <mper...@redhat.com>
Gerrit-Reviewer: Omer Frenkel <ofren...@redhat.com>
Gerrit-Reviewer: Roy Golan <rgo...@redhat.com>
Gerrit-Reviewer: oVirt Jenkins CI Server
Gerrit-HasComments: Yes
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