[Qemu-devel] (no subject)

[Ronnie Sahlberg]

Please find attached a patch to add built-in support for iSCSI into QEMU.
Please review and/or apply this patch.

This is the latest version of this patch and I think I have addressed all 
previous concerns and suggestions.


Using built-in iSCSI support has many advantages for certain use cases :

* if you have very many iSCSI devices it may be impractical to expose
all LUNs to the underlying host.

* the devices become private to the guest and are not visible to the host.
This automatically avoids polluting the page-cache on the host.

* security, the devices are private to the guest, which prevents other guests 
or the host itself from accessing the devices.

* security, it allows non-root users a secure way to get private and password 
protected access to the device by using CHAP authentication.

* migration, many other virtualization systems provide built-in iscsi clients 
like this. Also providing this as feature in QEMU may make it easier for such 
users to migrate over to QEMU/KVM.

* easier to maintain. For users with very many QEMU instances I think having 
guest-private iscsi targets and LUNs may be easier to manage than 'huge set of 
files in /dev/scsi/*'

* easier to maintain, when copying a QEMU instance from one host to another, 
this offers a more self-contained solution where the QEMU command line itself 
cotnains all required storage configuration, instead of also having to 
coordinate this move with setting up and tearing down open-iscsi logins on the 
underlying hosts.




The patch has been tested by installing and running several distributions such 
as RHEL6 and Ubuntu on devices, both system disk as well as the installer CDROM 
as being iscsi devices.

This testing has also been performed by running full QEMU under valgrind.

Performance is comparable to using open-iscsi devices.