On Sun, Sep 19, 2021 at 04:39:01AM -0600, Andreas Dilger wrote:
> What I don't understand here is why not just use a network
> filesystem that is explicitly designed for this task (eg. NFS or
> Ganesha on to of ext4)?
nbdkit-ext2-filter is very niche, but it's quite different from
anything NFS can do. For example:
$ nbdkit --filter=ext2 --filter=xz \
curl http://oirase.annexia.org/tmp/disk.img.xz \
ext2file=/disk/fedora-33.img
$ nbdinfo nbd://localhost
protocol: newstyle-fixed without TLS
export="":
export-size: 6442450944
content: DOS/MBR boot sector
uri: nbd://localhost:10809/
contexts:
base:allocation
is_rotational: false
is_read_only: true
can_cache: true
can_df: true
can_fast_zero: false
can_flush: true
can_fua: false
can_multi_conn: false
can_trim: false
can_zero: false
$ guestfish --ro --format=raw -a nbd://localhost -i
[...]
Operating system: Fedora 33 (Thirty Three)
/dev/sda3 mounted on /
/dev/sda2 mounted on /boot
What we're doing here is exporting a compressed ext4 image over HTTP
and then accessing a VM image inside it.
(This is a contrived example but it's similar to something called the
Containerized Data Importer in Kubernetes.)
Rich.
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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