[sheepdog-users] sheepdog tgt multipath

[Hitoshi Mitake]

On Tue, Apr 21, 2015 at 8:00 PM, Balázs Kónya <brokerka at gmail.com> wrote:
> Hello!
>
> First of all, sorry for my english! I'm wokring on it :)
>
> I want to set up sheepdog with tgt and multipath support.
> I'm a newbie.
>
> On Debian Wheezy, build 3 nodes of sheepdog, the latest from git, and tgt
> too.
>
> Everything working great, but i dont find any usabe "how-to" to setting up
> the multipath.
> I want to connect the sheeep cluster to XenServer with iSCSI
>
> XenServer discover the single iSCSI path and LUN, and use it correctly.
> But if one of my sheepdog node going to sleep with the fishies...after
> recovery....
> The corrupted node going online, recovery is success, and iSCSI resource
> starting on an other node...sheepdog, and iSCSI HA seeming correct (thanks
> to pacemaker, corosnyc)...but..
>
> Every time my VM's virtual disk become corrupted, but not the VDI inside
> sheepdog cluster..
> dog vdi check finishing successfully....
>
> The mailfuncion become inside the virtual machine...
>
> i found this article:
> https://www.mail-archive.com/sheepdog@lists.wpkg.org/msg13589.html
>
> This article descibes the same problem that i have!
>
> Based on this article, my sheepdog, and tgt is the latest...so multipath
> supporting is possibly ok..
>
> But how can i setup it, to work properly?

Hi Balázs,

At first, you need to format your cluster with "dog cluster -l" on the
latest master. It is not documented, sorry!

And the iSCSI feature of sheepdog doesn't depend on pacemaker (and the
combination might not work).
You just need to prepare two tgtd on two hosts, login with iSCSI
initiator with it, and use them in fail over policy.

In a case of multipathd of linux, you need to configure it with a
configuration file like below:
multipaths {
        multipath {
                wwid                    $SCSI_ID
                alias                   sheepdog-iscsi
                path_grouping_policy    failover
                path_checker            readsector0
                path_selector           "round-robin 0"
                failback                manual
                rr_weight               priorities
                no_path_retry           5
        }
}

# you need to specify scsi id to the $SCSI_ID

I don't know how to setup iSCSI multipath on XenServer, so I cannot
say anything about it :(

Could you try the above procedure?

Thanks,
Hitoshi

>
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