[libvirt] Re: [Patch v0.4] iSCSI Multi-IQN (Libvirt Support)

[Daniel P. Berrange]

On Wed, Nov 18, 2009 at 04:01:53PM +0530, Shyam_Iyer at Dell.com wrote:
> > -----Original Message-----
> > From: Daniel P. Berrange [mailto:berrange at redhat.com]
> > Sent: Wednesday, November 18, 2009 3:50 PM
> > To: Iyer, Shyam
> > Cc: dallan at redhat.com; Bellad, Sudhir; libvir-list at redhat.com; Domsch,
> > Matt; KM, Paniraja
> > Subject: Re: [libvirt] Re: [Patch v0.4] iSCSI Multi-IQN (Libvirt
> > Support)
> > 
> > On Wed, Nov 18, 2009 at 01:53:50AM +0530, Shyam_Iyer at Dell.com wrote:
> > > Iscsiadm's -I parameter takes iface name as the parameter value and
> > not
> > > the iqn name.
> > >
> > > So I believe this approach could be taken -
> > >
> > > 1) Get the iqn for the corresponding iface name using the following
> > > command
> > > #iscsiadm -m iface
> > >
> > > Example output:
> > >
> > > [root at localhost libvirt-0.7.1-15-org]# iscsiadm -m iface
> > > default tcp,default,default,unknown
> > > iser iser,default,default,unknown
> > > bnx2i bnx2i,default,default,unknown
> > > iface1 tcp,default,default,iqn.1994-05.com.fedora:iqnBellad
> > > iface3 tcp,default,default,iqn.dell
> > > iface0 tcp,unknown,unknown,iqn.1994-05.com.fedora:iqnSudhir
> > 
> > Ah, so where does this mapping come from ? Does the administrator have
> > to
> > create the mapping between interfaces & iqns, or is this totally
> > automatic
> > somehow ?
> > 
> 
> Today the iface file is created by by iscsi administrators using either
> of the following methods
> 
> 1) By hand by editing the iface parameters in
> /var/lib/iscsi/ifaces/<iface_file>
> 
> 
> Iface.iscsi_ifacename = <iface name>
> Iface.net_ifacename = <default, eth0 etc>
> Iface.hwaddress = <default, mac address etc>
> Iface.transport_name = <tcp, bnx2i etc>
> Iface.initiatorname = <iqn name>

This approach isn't really useful for us, since libvirt API is intended to
be usable remotely without any administrator login.

> 2) By using iscsiadm commands like the following
> # iscsiadm -m iface -I <iface_name> -o new
> # iscsiadm -m iface -I iface1 --op=update -n iface.initiatorname -v
> <iqnname>

In that case, why don't we make libvirt automatically set things up this
way whenever it sees the IQN in the XML file. 

> We don't change the default initiatorname with libvirt/virt manager
> today right ? So, we haven't added any apis to manage the iface file
> name using libvirt as such.
> 
> But if required by virt-manager(to create a single window of management)
> the iface file could be constructed using libvirt apis that call the
> iscsiadm commands detailed in method 2)

We don't need to add any new APIs for this - just automatically add the
mapping whenever logging into a target with a IQN that we don't already
know about


Regards,
Daniel
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