[Qemu-devel] QEMU detachable overlays and Union Mounts

If this message should go elsewhere, my apologies.

It would be great if QEMU have the capability of detachable overlay or union mount.
So administrators can keep each software as separate individual qcow2/qed disks and can put those disks on different layers so that the end user would see combination of the softwares available to them.

The desired scenario is like the following:-

-- -------------------- ----------------------- ----------------------

User1 Disk (RW) User2 Disk (RW) \ User3 Disk (RW)

----------------------- \ ---------------------- \ -----------------------

| \ | \ |

------------------------- \ ---------------------- \ ----------------------

Software 1 Disk \ Software 2 Disk \ Software 3 Disk

(Read Only) \ (Read Only) \ (Read Only)

-------------------------- ----------------------- ----------------------

--------------------------- -------------------------- ------------------------

(Hostname (VM1) (Hostname (VM2) (Hostname (VM3)

IP Address IP Address IP Address

Unique Data) Disk Unique Data) Disk Unique Data) Disk

(Read Only) (Read Only) / (Read Only)

--------------------------- --------------------------- / --------------------------

\ | /

\ --------------------------------------- /

\ | OS Updates Disk 2(RO) | /

\ ---------------------------------------- /

\ | OS Updates Disk 1 (RO) | /

\ ----------------------------------------- /

\ | Base VM Image (RO) |/

---------------------------

To User1:- To User2:- To User3:-

Hostname: - VM1 Hostname:-VM2 Hostname:-VM3

Software Installed: - Software1+Software2 Software Installed: - Software2+Software3 Software Installed:- Software3

Writable Disk:- User1 Disk Writable Disk:- User2 Disk Writable Disk:- User3 Disk

Please let me know if the above scenario is possible utilizing QEMU.

From:	kausik pal
Subject:	[Qemu-devel] QEMU detachable overlays and Union Mounts
Date:	Wed, 8 Jan 2014 11:26:28 +0530