Il 24-04-2019 00:13 Gionatan Danti ha scritto:
Hi all,
experimenting with vol-create-as, I think it should autodetect some
data - filesize and backing file format, specifically. However, the
current implementation require us to specify both filesize and backing
file format.
Considering that qemu-img already autodetects these data, there are
any reason for the lack of autodetect by libvirt? Should I open a
bugzilla issue?
Below you can find a practical example of what I mean. System is
CentOS Linux release 7.6.1810 (Core) with
libvirt-4.5.0-10.el7_6.4.x86_64
Please let me know if I am missing something.
Thanks.
# create base file
[root@singularity images]# qemu-img create base.qcow2 8G -f qcow2
Formatting 'base.qcow2', fmt=qcow2 size=8589934592 cluster_size=65536
lazy_refcounts=off refcount_bits=16
[root@singularity images]# qemu-img info base.qcow2
image: base.qcow2
file format: qcow2
virtual size: 8.0G (8589934592 bytes)
disk size: 17K
cluster_size: 65536
Format specific information:
compat: 1.1
lazy refcounts: false
refcount bits: 16
corrupt: false
# create overlay1.qcow2 via qemu-img; note how backing file format is
autodetected ("-f qcow2" regards the overlay file itself)
[root@singularity images]# qemu-img create -b
/var/lib/libvirt/images/base.qcow2 overlay1.qcow2 -f qcow2
Formatting 'overlay1.qcow2', fmt=qcow2 size=8589934592
backing_file=/var/lib/libvirt/images/base.qcow2 cluster_size=65536
lazy_refcounts=off refcount_bits=16
[root@singularity images]# qemu-img info overlay1.qcow2
image: overlay1.qcow2
file format: qcow2
virtual size: 8.0G (8589934592 bytes)
disk size: 17K
cluster_size: 65536
backing file: /var/lib/libvirt/images/base.qcow2
Format specific information:
compat: 1.1
lazy refcounts: false
refcount bits: 16
corrupt: false
# try the same with virsh vol-create-as; note how you must specify
filesize and the backing file format is *wrong* (leading to an
unusable overlay disk)
[root@singularity images]# virsh vol-create-as default overlay2.qcow2
8G --format qcow2 --backing-vol /var/lib/libvirt/images/base.qcow2
Vol overlay2.qcow2 created
[root@singularity images]# qemu-img info overlay2.qcow2
image: overlay2.qcow2
file format: qcow2
virtual size: 8.0G (8589934592 bytes)
disk size: 17K
cluster_size: 65536
backing file: /var/lib/libvirt/images/base.qcow2
backing file format: raw
Format specific information:
compat: 0.10
refcount bits: 16
Dear all,
any thoughts on the matter?
Thanks.
--
Danti Gionatan
Supporto Tecnico
Assyoma S.r.l. - www.assyoma.it
email: g.danti@xxxxxxxxxx - info@xxxxxxxxxx
GPG public key ID: FF5F32A8
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