[libvirt-users] Ang: Ang: vhba and storage pool creation

[Johan Kragsterman]

Hi again, again...!

Additional question AGAIN about multipath: If I add both luns(same multipath lu) to the config, perhaps is it so, that the guest VM will discover that it is the same device, and use them to configure an multipath device? I mean if it is a guest that has multipath capabilities, like centos7.




-----libvirt-users-bounces at redhat.com skrev: -----
Till: libvirt-users at redhat.com
Från: Johan Kragsterman 
Sänt av: libvirt-users-bounces at redhat.com
Datum: 2016-06-12 08:47
Ärende: [libvirt-users] Ang: vhba and storage pool creation


HI again!

I do have another question as well. See in the end.

-----libvirt-users-bounces at redhat.com skrev: -----
Till: libvirt-users at redhat.com
Från: Johan Kragsterman 
Sänt av: libvirt-users-bounces at redhat.com
Datum: 2016-06-12 08:30
Ärende: [libvirt-users] vhba and storage pool creation

Hi!


Got a couple of storage questions here.

I'm a storage guy, running a new project, and just started with libvirt, but have been using qemu/kvm on other platforms before, as well as oVirt.

So, my questions here:

I started with creating a vhba, and that went fine, I could see it on the storage side logging in to the target with its wwn.

My next step would be to make it persistent, and then its this storage pool creation I've seen.

Though some things are not clear to me. This is what the xml file looks like in the documentation:


<pool type='scsi'>
      <name>poolvhba0</name>
      <source>
        <adapter type='fc_host' wwnn='20000000c9831b4b' wwpn='10000000c9831b4b'/>
      </source>
      <target>
        <path>/dev/disk/by-path</path>
        <permissions>
          <mode>0700</mode>
          <owner>0</owner>
          <group>0</group>
        </permissions>
      </target>
    </pool>



So there are a few of these things that are unclear to me:

* It seems like I should NOT configure a vhba in advance, but this is the process that will configure the vhba for me?
* It also seems like the wwnn and wwpn set here are the ones that the vhba will use, not the parent hba?
* There is an option of setting the parent here as well, which I will need for some resons, but it is unclear to me whether the wwnn and wwpn's are from the parent or the vhba? Looks like this in documentation:

<source>
      <adapter type='fc_host' parent='scsi_host5' wwnn='20000000c9831b4b' wwpn='10000000c9831b4b'/>
    </source>

* So, are these wwpn and wwnn's from parent or vhba?
* Lastly, the path: In the xml file it says /dev/disk/by-path...but I have no path...? Since I have not yet configured the vhba, I can not have a path? I can not map a lun to the vhba before I have a vhba...
Or should I create a non persistent vhba, map a lun to it, and then source that path, use the wwpn and wwnn from that vhba in the scsi pool creation???

That would make sense, but also be a bit complicated to use...




The other question regards multipath. These luns are provided by an Fc SAN, so they're of coarse multipath luns. How do I set the /dev/disk/by-path for these?
I've seen there are multipath pools, but these doesn't seem to be the right way to go...?




Best regards from/Med vänliga hälsningar från

Johan Kragsterman

Capvert


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