On actual testing, I could see that kvmheartbeat.sh script fails on NFS
server failure and stops the agent only. Any HA VMs could be launched
in different hosts, and recovery of NFS server could lead to a state
where a HA enabled VM runs on two hosts and can potentially cause
disk corruptions. In most cases, VM disk corruption will be worse than
VM downtime. I've kept the sleep interval between check/rounds but
reduced it to 10s. The change in behaviour was introduced in #2722.
Signed-off-by: Rohit Yadav <rohit.yadav@shapeblue.com>
The recent discussed improvement has the risk that if 'sync' hangs, the reboot may be delayed in the same way as the 'reboot' command would do. To work around, we're adding a 5 second timeout. If it cannot sync in 5 seconds, it will not succeed anyway and we should proceed the reset.
@snuf: Could we use your OVM3 heartbeat script for other hypervisors as well? One way to do it seems like a nice idea :-)
As discussed with @wido @pyr and @nuxro added an extra log line.
Tested it and it logs fine (tested to local disk) when syncing first:
Apr 3 15:31:23 mcctest2 heartbeat: kvmheartbeat.sh system because it was unable to write the heartbeat to the storage
By the way, it did also log to the agent.log but this extra log has the benefit of ending up in the system log so you'll probably find it easier there. Existing logs:
2015-04-03 15:27:23,943 WARN [kvm.resource.KVMHAMonitor] (Thread-24:null) write heartbeat failed: timeout, retry: 0
2015-04-03 15:28:23,944 WARN [kvm.resource.KVMHAMonitor] (Thread-24:null) write heartbeat failed: timeout, retry: 1
2015-04-03 15:29:23,946 WARN [kvm.resource.KVMHAMonitor] (Thread-24:null) write heartbeat failed: timeout, retry: 2
2015-04-03 15:30:23,948 WARN [kvm.resource.KVMHAMonitor] (Thread-24:null) write heartbeat failed: timeout, retry: 3
2015-04-03 15:31:23,950 WARN [kvm.resource.KVMHAMonitor] (Thread-24:null) write heartbeat failed: timeout, retry: 4
2015-04-03 15:31:23,950 WARN [kvm.resource.KVMHAMonitor] (Thread-24:null) write heartbeat failed: timeout; reboot the host
This closes#145
Signed-off-by: Rohit Yadav <rohit.yadav@shapeblue.com>
When storage cannot be reached, it does not make sense to reboot as it will try to flush buffers, umount NFS mounts, etc. This will not work and thus cause a long delay. With this change, the box will reboot immediately (like pressing the reset button).
host if there are multiple storage pools in a cluster.
The issue is as follows:
1. When CloudStack detects that a host is not responding to ping
requests it'll send a fence command for this host to another host in the
cluster.
2. The agent takes a long time to respond to this check if the storage
is fenced. This is because the agent checks if the first host is writing
to its heartbeat file on all pools in the cluster. It is doing this in a
sequential manner on all storage pool.
Making a fix to get rid of sleep, wait during HA. The behavior is now
similar to Xenserver.
RB: https://reviews.apache.org/r/6133/
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