[Pacemaker] Two node cluster and no hardware device for stonith.

[emmanuel segura]

In normal situation every node can in your file system, fence_scsi is
used when your cluster is in split-braint, when your a node doesn't
comunicate with the other node, i don't is good idea.


2015-01-27 11:35 GMT+01:00 Andrea <a.bacchi at codices.com>:
> Andrea <a.bacchi at ...> writes:
>
>>
>> Michael Schwartzkopff <ms <at> ...> writes:
>>
>> >
>> > Am Donnerstag, 22. Januar 2015, 10:03:38 schrieb E. Kuemmerle:
>> > > On 21.01.2015 11:18 Digimer wrote:
>> > > > On 21/01/15 08:13 AM, Andrea wrote:
>> > > >> > Hi All,
>> > > >> >
>> > > >> > I have a question about stonith
>> > > >> > In my scenarion , I have to create 2 node cluster, but I don't
>> >
>> > Are you sure that you do not have fencing hardware? Perhaps you just did
> nit
>> > configure it? Please read the manual of you BIOS and check your system
>> board if
>> > you have a IPMI interface.
>> >
>>
>> > > >> > In my test, when I simulate network failure, split brain occurs, and
>> > > >> > when
>> > > >> > network come back, One node kill the other node
>> > > >> > -log on node 1:
>> > > >> > Jan 21 11:45:28 corosync [CMAN  ] memb: Sending KILL to node 2
>> > > >> >
>> > > >> > -log on node 2:
>> > > >> > Jan 21 11:45:28 corosync [CMAN  ] memb: got KILL for node 2
>> >
>> > That is how fencing works.
>> >
>> > Mit freundlichen Grüßen,
>> >
>> > Michael Schwartzkopff
>> >
>>
>> Hi All
>>
>> many thanks for your replies.
>> I will update my scenario to ask about adding some devices for stonith
>> - Option 1
>> I will ask for having 2 vmware virtual machine, so i can try fance_vmware
>> -Option 2
>> In the project, maybe will need a shared storage. In this case, the shared
>> storage will be a NAS that a can add to my nodes via iscsi. In this case I
>> can try fence_scsi
>>
>> I will write here about news
>>
>> Many thanks  to all for support
>> Andrea
>>
>
>
>
> some news
>
> - Option 2
> In the customer environment I configured a iscsi target that our project
> will use as cluster filesystem
>
> [ONE]pvcreate /dev/sdb
> [ONE]vgcreate -Ay -cy cluster_vg /dev/sdb
> [ONE]lvcreate -L*G -n cluster_lv cluster_vg
> [ONE]mkfs.gfs2 -j2 -p lock_dlm -t ProjectHA:ArchiveFS /dev/cluster_vg/cluster_lv
>
> now I can add a Filesystem resource
>
> [ONE]pcs resource create clusterfs Filesystem
> device="/dev/cluster_vg/cluster_lv" directory="/var/mountpoint"
> fstype="gfs2" "options=noatime" op monitor interval=10s clone interleave=true
>
> and I can read and write from both node.
>
>
> Now I'd like to use this device with fence_scsi.
> It is ok? because I see in the man page this:
> "The fence_scsi agent works by having each node in the cluster register a
> unique key with the SCSI devive(s). Once registered, a single node will
> become the reservation holder by creating  a  "write  exclu-sive,
> registrants only" reservation on the device(s). The result is that only
> registered nodes may write to the device(s)"
> It's no good for me, I need both node can write on the device.
> So, I need another device to use with fence_scsi? In this case I will try to
> create two partition, sdb1 and sdb2, on this device and use sdb1 as
> clusterfs and sdb2 for fencing.
>
>
> If i try to manually test this, I obtain before any operation
> [ONE]sg_persist -n --read-keys
> --device=/dev/disk/by-id/scsi-36e843b608e55bb8d6d72d43bfdbc47d4
>   PR generation=0x27, 1 registered reservation key follows:
>     0x98343e580002734d
>
>
> Then, I try to set serverHA1 key
> [serverHA1]fence_scsi -d
> /dev/disk/by-id/scsi-36e843b608e55bb8d6d72d43bfdbc47d4 -f /tmp/miolog.txt -n
> serverHA1 -o on
>
> But nothing has changed
> [ONE]sg_persist -n --read-keys
> --device=/dev/disk/by-id/scsi-36e843b608e55bb8d6d72d43bfdbc47d4
>   PR generation=0x27, 1 registered reservation key follows:
>     0x98343e580002734d
>
>
> and in the log:
> gen 26 17:53:27 fence_scsi: [debug] main::do_register_ignore
> (node_key=4d5a0001, dev=/dev/sde)
> gen 26 17:53:27 fence_scsi: [debug] main::do_reset (dev=/dev/sde, status=6)
> gen 26 17:53:27 fence_scsi: [debug] main::do_register_ignore (err=0)
>
> The same when i try on serverHA2
> It is normal?
>
>
> In any case, i try to create a stonith device
> [ONE]pcs stonith create iscsi-stonith-device fence_scsi
> pcmk_host_list="serverHA1 serverHA2"
> devices=/dev/disk/by-id/scsi-36e843b608e55bb8d6d72d43bfdbc47d4 meta
> provides=unfencing
>
> and the cluster status is ok
> [ONE] pcs status
> Cluster name: MyCluHA
> Last updated: Tue Jan 27 11:21:48 2015
> Last change: Tue Jan 27 10:46:57 2015
> Stack: cman
> Current DC: serverHA1 - partition with quorum
> Version: 1.1.11-97629de
> 2 Nodes configured
> 5 Resources configured
>
>
> Online: [ serverHA1 serverHA2 ]
>
> Full list of resources:
>
>  Clone Set: ping-clone [ping]
>      Started: [ serverHA1 serverHA2 ]
>  Clone Set: clusterfs-clone [clusterfs]
>      Started: [ serverHA1 serverHA2 ]
>  iscsi-stonith-device   (stonith:fence_scsi):   Started serverHA1
>
>
>
> How I can try this from remote connection?
>
>
> Andrea
>
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