Re: Xen DomU zvol disk sizes

[Sebastian <sebastian%xenoserver.net@localhost>]

Am 2025-12-18 19:39, schrieb Sebastian:

> If I now create a zvol with 10G size and start a NetBSD 10.1 (PV mode) 
> the zvol appears in the DomU, but the disk size inside the DomU is only 
> 25% (2^2??). I tried with different zvol blockvolsizes but without any 
> effect.

There is the configuration I tried:

Create a new zvol:

    zfs create -p -V 16G zredpool/test
    newfs -O2 /dev/zvol/rdsk/zredpool/test

zfs list:

    NAME                    USED  AVAIL  REFER  MOUNTPOINT
    zredpool/test          16.5G   322G  3.24M  -


The Xen DomU disk spec looks like this:

    disk = [
            'format=raw, vdev=xvda, 
target=/zredpool/xenstore/test/root.img',
            'vdev=xvdb, target=/dev/zvol/dsk/zredpool/test'
    ]

But in my DomU guest I get

    [   1.9800368] xbd0 at xenbus0 id 51712: Xen Virtual Block Device 
Interface
    [   1.9903955] xbd1 at xenbus0 id 51728: Xen Virtual Block Device 
Interface
    [   1.9903955] xbd0: 10240 MB, 512 bytes/sect x 20971520 sectors
    [   1.9903955] xbd0: backend features 0x1<CACHE-FLUSH>
    [   1.9903955] unknown type vkbd at xenbus0 id 0 not configured
    [   1.9903955] unknown type vfb at xenbus0 id 0 not configured
    [   1.9903955] xbd1: 2048 MB, 512 bytes/sect x 4194304 sectors
    [   1.9903955] xbd1: backend features 0x1<CACHE-FLUSH>

When I try to mount the pre-formatted xbd1 it fails because of incorrect 
super block size. I also see the same "wrong" disk size in linux DomUs.

Best regards,
Sebastian