5:31 a.m.
Hi again!
-----libvirt-users-bounces(a)redhat.com skrev: -----
Till: Yuan Dan <dyuan(a)redhat.com>
Från: Johan Kragsterman
Sänt av: libvirt-users-bounces(a)redhat.com
Datum: 2016-08-24 07:52
Kopia: libvirt-users(a)redhat.com
Ärende: [libvirt-users] Ang: Re: Ang: Re: attaching storage pool error
Hi and thanks for your important input,Dan!
>
>
> System centos7, system default libvirt version.
>
> I've succeeded to create an npiv storage pool, which I could start without
> problems. Though I couldn't attach it to the vm, it throwed errors when
> trying. I want to boot from it, so I need it working from start. I read one
> of Daniel Berrange's old(2010) blogs about attaching an iScsi pool, and
> draw
> my conclusions from that. Other documentation I haven't found. Someone can
> point me to a more recent documentation of this?
>
> Are there other mailing list in the libvirt/KVM communities that are more
> focused on storage? I'd like to know about these, if so, since I'm a
> storage
> guy, and fiddle around a lot with these things...
>
> There are quite a few things I'd like to know about, that I doubt this list
> cares about, or have knowledge about, like multipath devices/pools,
> virtio-scsi in combination with npiv-storagepool, etc.
>
> So anyone that can point me further....?
http://libvirt.org/formatstorage.html
https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/7/...
Hope it can help you to get start with it.
Unfortunatly I have already gone through these documents, several times as
well, but these are only about the creation of storage pools, not how you
attach them to the guest.
If the pool is ready, here are kinds of examples
http://libvirt.org/formatdomain.html#elementsDisks
you can use it in guest like this:
<disk type='volume' device='disk'>
<driver name='qemu' type='raw'/>
<source pool='iscsi-pool' volume='unit:0:0:1'
mode='host'/>
<auth username='myuser'>
<secret type='iscsi' usage='libvirtiscsi'/>
</auth>
<target dev='vdb' bus='virtio'/>
</disk>
As I described above, I created an npiv pool for my FC backend. I'd also like to get
scsi pass through, which seems to be possible only if I use "device=lun". Can I
NOT use "device=lun", and then obviously NOT get "scsi pass through",
if I use an npiv storage pool? Is the only way to get "scsi pass through" to NOT
use a storage pool, but instead use the host lun's?
What do you think about this?:
<disk type='volume' device='disk'>
<driver name='qemu' type='raw'/>
<source pool='vhbapool_host8' volume='unit:0:0:1'/>
<target dev='hda' bus='ide'/>
</disk>
But I'd prefer to be able to use something like this instead:
<disk type='volume' device='lun'>
<driver name='qemu' type='raw'/>
<source pool='vhbapool_host8' volume='unit:0:0:1'/>
<target dev='vda' bus='scsi'/>
</disk>
But that might not be possible...?
A couple of additional questions here:
* Since the target device is already defined in the pool, I don't see the reason for
defining it here as well, like in your example with the iscsi pool?
* I'd like to use virtio-scsi combined with the pool, is that possible?
* If so, how do I define that? I understand I can define a controller separatly, but how
do I tell the guest to use that specific controller in combination with that pool?
* Since the npiv pool obviously is a pool based on an fc initiator, the fc target can/will
provision more lun's to that initiator, how will that effect the pool and the
guest's access to new lun's? In this example the volume says 'unit:0:0:1',
and I guess that will change if there will be more lun's in there? Or is that
"volume unit" the "scsi target device", and can hold multiple
lun's?
...more...
I've found something here in the RHEL7 virt guide:
<disk type='volume' device='lun' sgio='unfiltered'>
<driver name='qemu' type='raw'/>
<source pool='vhbapool_host3' volume='unit:0:0:0'/>
<target dev='sda' bus='scsi'/>
<shareable />
</disk>
Question that shows up here is the multipath question. Since this is fibre channel it is
of coarse multipath. The "target dev" says 'sda'. In a multipath dev
list it should say "/dev/mapper/mpatha".
How to handle that?
>
> Rgrds Johan
>
>
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