[ClusterLabs] fence_scsi no such device

[marvin]

On 03/21/2016 03:46 PM, Ken Gaillot wrote:
> On 03/21/2016 08:39 AM, marvin wrote:
>>
>> On 03/15/2016 03:39 PM, Ken Gaillot wrote:
>>> On 03/15/2016 09:10 AM, marvin wrote:
>>>> Hi,
>>>>
>>>> I'm trying to get fence_scsi working, but i get "no such device" error.
>>>> It's a two node cluster with nodes called "node01" and "node03". The OS
>>>> is RHEL 7.2.
>>>>
>>>> here is some relevant info:
>>>>
>>>> # pcs status
>>>> Cluster name: testrhel7cluster
>>>> Last updated: Tue Mar 15 15:05:40 2016          Last change: Tue Mar 15
>>>> 14:33:39 2016 by root via cibadmin on node01
>>>> Stack: corosync
>>>> Current DC: node03 (version 1.1.13-10.el7-44eb2dd) - partition with
>>>> quorum
>>>> 2 nodes and 23 resources configured
>>>>
>>>> Online: [ node01 node03 ]
>>>>
>>>> Full list of resources:
>>>>
>>>>    Clone Set: dlm-clone [dlm]
>>>>        Started: [ node01 node03 ]
>>>>    Clone Set: clvmd-clone [clvmd]
>>>>        Started: [ node01 node03 ]
>>>>    fence-node1    (stonith:fence_ipmilan):        Started node03
>>>>    fence-node3    (stonith:fence_ipmilan):        Started node01
>>>>    Resource Group: test_grupa
>>>>        test_ip    (ocf::heartbeat:IPaddr):        Started node01
>>>>        lv_testdbcl        (ocf::heartbeat:LVM):   Started node01
>>>>        fs_testdbcl        (ocf::heartbeat:Filesystem):    Started node01
>>>>        oracle11_baza      (ocf::heartbeat:oracle):        Started node01
>>>>        oracle11_lsnr      (ocf::heartbeat:oralsnr):       Started node01
>>>>    fence-scsi-node1       (stonith:fence_scsi):   Started node03
>>>>    fence-scsi-node3       (stonith:fence_scsi):   Started node01
>>>>
>>>> PCSD Status:
>>>>     node01: Online
>>>>     node03: Online
>>>>
>>>> Daemon Status:
>>>>     corosync: active/enabled
>>>>     pacemaker: active/enabled
>>>>     pcsd: active/enabled
>>>>
>>>> # pcs stonith show
>>>>    fence-node1    (stonith:fence_ipmilan):        Started node03
>>>>    fence-node3    (stonith:fence_ipmilan):        Started node01
>>>>    fence-scsi-node1       (stonith:fence_scsi):   Started node03
>>>>    fence-scsi-node3       (stonith:fence_scsi):   Started node01
>>>>    Node: node01
>>>>     Level 1 - fence-scsi-node3
>>>>     Level 2 - fence-node3
>>>>    Node: node03
>>>>     Level 1 - fence-scsi-node1
>>>>     Level 2 - fence-node1
>>>>
>>>> # pcs stonith show fence-scsi-node1 --all
>>>>    Resource: fence-scsi-node1 (class=stonith type=fence_scsi)
>>>>     Attributes: pcmk_host_list=node01 pcmk_monitor_action=metadata
>>>> pcmk_reboot_action=off
>>>>     Meta Attrs: provides=unfencing
>>>>     Operations: monitor interval=60s
>>>> (fence-scsi-node1-monitor-interval-60s)
>>>>
>>>> # pcs stonith show fence-scsi-node3 --all
>>>>    Resource: fence-scsi-node3 (class=stonith type=fence_scsi)
>>>>     Attributes: pcmk_host_list=node03 pcmk_monitor_action=metadata
>>>> pcmk_reboot_action=off
>>>>     Meta Attrs: provides=unfencing
>>>>     Operations: monitor interval=60s
>>>> (fence-scsi-node3-monitor-interval-60s)
>>>>
>>>> node01 # pcs stonith fence node03
>>>> Error: unable to fence 'node03'
>>>> Command failed: No such device
>>>>
>>>> node01 # tail /var/log/messages
>>>> Mar 15 14:54:04 node01 stonith-ng[20024]:  notice: Client
>>>> stonith_admin.29191.2b7fe910 wants to fence (reboot) 'node03' with
>>>> device '(any)'
>>>> Mar 15 14:54:04 node01 stonith-ng[20024]:  notice: Initiating remote
>>>> operation reboot for node03: d1df9201-5bb1-447f-9b40-d3d7235c3d0a (0)
>>>> Mar 15 14:54:04 node01 stonith-ng[20024]:  notice: fence-scsi-node3 can
>>>> fence (reboot) node03: static-list
>>>> Mar 15 14:54:04 node01 stonith-ng[20024]:  notice: fence-node3 can fence
>>>> (reboot) node03: static-list
>>>> Mar 15 14:54:04 node01 stonith-ng[20024]:  notice: All fencing options
>>>> to fence node03 for stonith_admin.29191 at node01.d1df9201 failed
>>> The above line is the key. Both of the devices registered for node03
>>> returned failure. Pacemaker then looked for any other device capable of
>>> fencing node03 and there is none, so that's why it reported "No such
>>> device" (an admittedly obscure message).
>>>
>>> It looks like the fence agents require more configuration options than
>>> you have set. If you run "/path/to/fence/agent -o metadata", you can see
>>> the available options. It's a good idea to first get the agent running
>>> successfully manually on the command line ("status" command is usually
>>> sufficient), then put those same options in the cluster configuration.
>>>
>> Made some progress, found new issue.
>> So i get the scsi_fence to work, it unfences at start, and fences when i
>> tell it to.
>>
>> The problem is when I, for instance, fence node01. It stops pacemaker
>> but leaves corosync, so node01 is in "pending" state and node03 won't
>> stop services until node01 is restarted. The keys seem to be handled
>> correctly.
> Technically, fence_scsi won't stop pacemaker or corosync, it will just
> cut off the node's disk access and let the cluster know it's safe to
> recover resources.
>
> I haven't used fence_scsi myself, so I'm not sure of the exact details,
> but your configuration needs some changes. The pcmk_host_list option
> should list only the one node that the fence device can fence (one
> device configured for each node). You need more attributes, such as
> "devices" to specify which SCSI devices to cut off, and either "key" or
> "nodename" to specify the node key for SCSI reservations.
>
I'll give it a try, but all those should be automagic if you don't 
define them (obviously it detects disk since i don't have them defined, 
and the keys are different on each node). At least that's what 
documentation claims.
According to https://access.redhat.com/articles/530533
"Normally |fence_scsi| will automatically detect which devices to 
manage, by checking which are physical volumes in volume groups marked 
with the "clustered" attribute. "
And this seems to work.

The other thing is, if i put only single node in pcmk_host_list either 
fence or unfence doesn't work. Additionally, in same documentation from 
redhat:
"|pcmk_host_list="node1.example.com node2.example.com"|: |stonith-ng| 
tries to dynamically determine which nodes can fence which nodes, but 
|fence_scsi| does not support this. Instead, we tell it which nodes are 
managed by this device. All nodes should be listed here."
Now does this mean all nodes fenced, or all nodes in cluster?

The tests:
1. changing pcmk_host_list to oposite node fences exactly the same as 
with all nodes listed, yet unfencing doesn't work
2. changing pcmk_host_list to same node fails at fencing with:
ERROR:root:Failed: keys cannot be same. You can not fence yourself.
Failed: keys cannot be same. You can not fence yourself.
as one would expect.

I can do additional tests with adding keys and disk by hand, but those 
seem to be handled correctly by the agent.
Only reasonable conclusion i can get from this is that i should use this 
as level two fencing, when the connection between nodes breaks and ipmi 
fencing doesn't confirm (node without power for example), to let the 
live node run the services.
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