From: Stuart D Gathman <stuart@gathman.org>
To: LVM general discussion and development <linux-lvm@redhat.com>
Cc: Zhiyong Ye <yezhiyong@bytedance.com>, damon.devops@gmail.com
Subject: Re: [linux-lvm] How to implement live migration of VMs in thinlv after using lvmlockd
Date: Tue, 1 Nov 2022 14:08:21 -0400 (EDT) [thread overview]
Message-ID: <f7403695-5d43-cfea-31b9-70a58b93a0c0@gathman.org> (raw)
In-Reply-To: <20221101144230.GA11193@redhat.com>
Z> On Tue, Nov 01, 2022 at 01:36:17PM +0800, Zhiyong Ye wrote:
>> I want to implement live migration of VMs in the lvm + lvmlockd + sanlock
>> environment. There are multiple hosts in the cluster using the same iscsi
>> connection, and the VMs are running on this environment using thinlv
>> volumes. But if want to live migrate the vm, it will be difficult since
>> thinlv which from the same thin pool can only be exclusive active on one
>> host.
I just expose the LV (thin or not - I prefer not) as an iSCSI target
that the VM boots from. There is only one host that manages a thin pool,
and that is a single point of failure, but no locking issues. You
issue the LVM commands on the iSCSI server (which I guess they call NAS
these days).
If you need a way for a VM to request enlarging an LV it accesses, or
similar interaction, I would make a simple API where each VM gets a
token that determines what LVs it has access to and how much total
storage it can consume. Maybe someone has already done that.
I just issue the commands on the LVM/NAS/iSCSI host.
I haven't done this, but there can be more than one thin pool, each on
it's own NAS/iSCSI server. So if one storage server crashes, then
only the VMs attached to it crash. You can only (simply) migrate a VM
to another VM host on the same storage server.
BUT, you can migrate a VM to another host less instantly using DRBD
or other remote mirroring driver. I have done this. You get the
remote LV mirror mostly synced, suspend the VM (to a file if you need
to rsync that to the remote), finish the sync of the LV(s), resume the
VM on the new server - in another city. Handy when you have a few hours
notice of a natural disaster (hurricane/flood).
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next prev parent reply other threads:[~2022-11-01 18:37 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-01 5:36 [linux-lvm] How to implement live migration of VMs in thinlv after using lvmlockd Zhiyong Ye
2022-11-01 14:42 ` David Teigland
2022-11-01 17:02 ` Zhiyong Ye
2022-11-01 17:57 ` David Teigland
2022-11-01 18:15 ` Demi Marie Obenour
2022-11-02 9:18 ` Zhiyong Ye
2022-11-02 9:01 ` Zhiyong Ye
2022-11-01 18:08 ` Stuart D Gathman [this message]
2022-11-02 9:31 ` Zhiyong Ye
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