Which one of the following statements is true about the live migration feature of Xen?

The correct answer is A. It requires that the source and destination hosts have access, with same rights, to the device that. See the full explanation below for the reasoning.

Question

Options

AIt requires that the source and destination hosts have access, with same rights, to the device that
BIt is used to migrate the file system of virtual machines between two hosts on the same network
CIt is recommended that the virtual machines be restarted after migration to ensure that network
DIt requires that the virtual machines are turned off to ensure that data stored in the RAM of the
EIt is used to convert physical servers into virtual machines without having to stop the physical servers.

How the community answered

(41 responses)

A
80% (33)
B
10% (4)
C
2% (1)
D
5% (2)
E
2% (1)

Community Discussion

Bao N.May 9, 2026

A is the one. Xen live migration needs both the source and destination hosts to have shared storage access with the same rights so the VM's disk image is reachable from either side during the handoff, otherwise the migrating VM loses its data path mid-transfer.

Thiago A.May 9, 2026

Correct on the shared storage requirement, but worth tightening up the "same rights" part since what Xen actually hands off is the block device or file path string verbatim to the destination dom0, so if your NFS export is mounted at /var/lib/xen/images on the source but /mnt/xen on the destination, the migration blows up even if permissions are identical on both sides.

Viktor S.Jan 25, 2026

A is correct. Xen live migration moves a running VM from one host to another with minimal downtime, but it has a hard requirement on shared storage: both the source and destination hypervisors need identical access rights to the underlying block device or storage volume that backs the VM. If they do not have the same rights, the destination host cannot take over disk I/O and the migration fails. The rest of the options describe things that are either the opposite of what live migration does or flat out wrong. D describes cold migration, not live. E describes P2V conversion, a completely different tool. B and C are nonsense distractors that do not reflect how Xen works at all. Learn the shared storage requirement and the distinction between live, offline, and P2V migration and you will not get tripped up by variants of this question on the real exam.

Anjali D.Jan 27, 2026

Good breakdown, Viktor, and worth adding that on exam variants the shared storage requirement usually surfaces as a mention of NFS or a SAN, so training yourself to pair those terms with live migration will help you eliminate distractors faster under time pressure.

Wesley A.Jan 7, 2026

I was eyeing E because "live" sounds like it means the server keeps running during conversion, but that is P2V migration, not Xen live migration at all. The thing that locked in A for me was remembering that live migration moves a running VM between hosts and both sides absolutely need access to the same shared storage with identical permissions, otherwise the VM just dies mid-move.

Anjali D.Jan 8, 2026

Wesley, you nailed the core mechanic, and I would add that the shared storage requirement is exactly why people get tripped up in lab environments where they forget to configure the storage pool identically on both hosts before attempting the move.

Grace U.May 23, 2026

The trick with this question is that the word "live" is doing a lot of heavy lifting. Live migration means the VM keeps running the whole time, so anything that requires a shutdown immediately rules itself out, and you can quietly cross off a couple of options before you even dig into the details. The key thing Xen needs to pull this off is that both the source and destination hosts can reach the same underlying storage with identical permissions, because the VM's disk is not being copied, it is just being handed off. Think about what would happen if the destination host had read-only access while the source had read-write, that handoff would break instantly. Here is what I am genuinely curious about, because I think it sharpens the concept: in your mental model, is the shared storage requirement a Xen-specific limitation, or do you think most hypervisors doing live migration share that same constraint? Sitting with that question might help you see why option A is the one that holds up.

Anjali D.Jan 16, 2026

Good catch on A being the right answer here, since Xen live migration depends on shared storage so both hosts can read and write the same disk image without copying it. Quick question for the group though, does anyone know whether that shared storage requirement applies equally to both paravirtualized and fully virtualized guests, or does the behavior differ depending on the virtualization mode?

Carlos M.May 1, 2026

Took this one on my 117-304 back in March and I almost picked E because I kept confusing live migration with P2V conversion, but then I remembered that Xen live migration specifically needs shared storage accessible by both hosts with the same permissions, which is exactly what A describes. Once you lock that distinction in your head, the other options fall apart pretty fast.

Prof. SaraMay 1, 2026

Solid lock on the shared-storage requirement, though worth adding that same-permission access is necessary but not sufficient on its own, since the hosts also need to be running compatible Xen versions or you will get a migration failure that looks deceptively like a storage permissions error.

Thiago A.Apr 27, 2026

A is the one. Xen live migration works by transferring the memory state of a running domU across the wire while the disk image stays put on shared storage, which means both the source and destination dom0 hosts must be able to mount and write to that same block device or NFS export with identical permissions, otherwise the destination has nowhere to land the guest. B and E are describing completely different operations, P2V conversion and filesystem rsync have nothing to do with live migration, and D describes cold migration, which defeats the whole point. C is just wrong, restarting after a live migration means you did something wrong and you lost the uptime benefit entirely. I hit this exact question on my 304 sitting back in 2019 and almost second-guessed myself toward D because the word "RAM" in that option made me pause, but then I remembered the xl migrate man page, section on shared storage requirements, and that snapped me back. Shared storage access parity between source and destination is the hard prerequisite the exam writers love to test because it is the most operationally painful part of setting up a Xen cluster in real life.

Prof. SaraApr 22, 2026

Restart post-migration locks in network continuity, C is textbook.

-2

Thiago A.Apr 24, 2026

Respectfully, Sara, a restart breaks active sessions and is not required here. A is correct because the change takes effect immediately through the running daemon without dropping existing connections.

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