Re: kern/53616: dom0 crashes when dumping domU images with vnd+fss

[Frédéric Fauberteau <triaxx%NetBSD.org@localhost>]

Le 2018-09-19 07:59, Manuel Bouyer a écrit :
> I don't think that will help. The problem is the fs is modified by the 
> VM
> while dom0 has it mounted.

At the best of my understanding, xen uses vnd to mount image files:
# vndconfig -l
vnd0: /srv/xen (/dev/mapper/vg0-lvxen) inode 3
vnd1: /srv/xen (/dev/mapper/vg0-lvxen) inode 4
vnd2: /srv/xen (/dev/mapper/vg0-lvxen) inode 5
vnd3: /srv/xen (/dev/mapper/vg0-lvxen) inode 5

I have launched my backup process. vnd3 is the image file manually 
attached. But vnd{0,1,2} seem to have been mounted by xen (if I 
understand correctly). The filesystem of my third VM is mounted twice by 
dom0.
Do you think a could make a fss snapshtop over vnd2 (third VM image) 
without manually attach it to vnd3 ?

> The closest way to mimic what you could do with lvm would be to 
> snapshot
> the filesystem containing the disk images, and mount the snapshot to 
> backup
> them.

Here, I could make a snapshot of /dev/mapper/vg0-lvxen. Thanks for the 
idea!

Do you think I have a chance to identify from where the problem exactly 
comes? Or it will be better to close this PR due to misuse of dom0?