Re: [libvirt] [RFC] Multi-IQN proposal
On Sat, Sep 26, 2009 at 12:45:03AM +0530, Shyam_Iyer(a)Dell.com wrote:
Would this proposal be acceptable ?
It is hard to say. Can you try and explain what it actually does,
and/or what you are trying to achieve ? Googling for more docs / info
about 'Multi-IQN' returns this mailing thread as the top hit which
doesn't really help understanding.
Example XML schema for an iSCSI storage pool created --
<pool type="iscsi">
<name>dell</name>
<uuid>cf354733-b01b-8870-2040-94888640e24d</uuid>
<capacity>0</capacity>
<allocation>0</allocation>
<available>0</available>
- <source>
<initiator iqnname = "<initiator IQN1>">
<initiator iqnname = "<initiator IQN2>">
........................................
........................................
<host name="<iSCSI target hostname or Target IP address>" />
<device path="<iSCSI Target IQN name>" />
</source>
- <target>
<path>/dev/disk/by-path</path>
- <permissions>
<mode>0700</mode>
<owner>0</owner>
<group>0</group>
</permissions>
</target>
</pool>
Each initiator iqn name can be parsed to create the unique sessions.
This doesn't make a whole lot of sense - for each iSCSI storage pool
defined in libvirt there is exactly one iSCSI session. So I'm not
really following why we'd need multiple IQN names in a single pool
if that were to imply in multiple sessions.
Ultimately a storage pool in libvirt is all about listing volumes,
and optionally creating/deleting volumes. iSCSI pools can only
list volumes, where each volume corresponds to a LUN in the iSCSI
target configured for the pool. So what effect does Multi-IQN have
on the process of enumerating LUNs ?
This should solve the following possibilities --
* possibility of multiple IQNs for a single Guest
* option for Guest's own BIOS & initiator to use these IQNs (iSCSI in
Guest)
* option for hypervisor's initiator to use these IQNs on behalf of the
guest
(Multi-IQN)
Compile tested only. Needs beatification.
The patch doesn't seem to actually do anything beyond parsing the
extra XML data - what is it actually to be used for in the iSCSI
storage implementation in storage_backend_iscsi.c ?
Regards,
Daniel
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