[lxc-users] Its possible to add a xen virtual device to an lxc container?

[Márcio Castro]

Hi Fajar,

Thank you very much for your response, and sorry - I think i know very
little about the linux operating system, and I never added a disk in an
environment with Linux Container.

I made several attempts, including a partition of one of my disks, but I
did not succeed.

So I decided to simplify my problem, trying this time with a virtual disk.

A - Quick guess, /dev/xvda did not exist before you ran dd?
No.

B - Do you know the difference between a file and block device? If my guess
is correct, you have just created a regular file /dev/xvda. That is not a
xen virtual device.
No, I do not know exactly the difference.

Can you help me with a litle explanation or direct me to some website with
more information about it?


What i do:

https://www.oreilly.com/library/view/linux-device-drivers/0596000081/ch01s03.html

"Like char devices, block devices are accessed by filesystem nodes in the
/dev directory. A block device is something that can host a filesystem,
such as a disk."

I understand that what aI need is a block device. I want to create a
virtual disk in the host, and in the container, i need to see this as a
disk. I need to format the virtual disk in the container. And to implement
RAC, i need a shared virtual disk, because this will me acessed by n
containers.


mmoura at mmoura-W350STQ-W370ST:~/DiscosVirtuais$ pwd
/home/mmoura/DiscosVirtuais

dd if=/dev/zero of=1GB_HDD.img bs=1M count=1024
fdisk 1GB_HDD.img
mkfs.ext4 1GB_HDD.img
sudo losetup -Pf --show 1GB_HDD.img

mmoura at mmoura-W350STQ-W370ST:~/DiscosVirtuais$ lsblk
NAME   MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
loop24   7:24   0     1G  0 loop

sudo mount -t ext4 /dev/loop24 /mnt

mmoura at mmoura-W350STQ-W370ST:~/DiscosVirtuais$ df -h
Sist. Arq.      Tam. Usado Disp. Uso% Montado em
/dev/loop24     976M  2,6M  907M   1% /mnt

lxc start ol7testedisc

mmoura at mmoura-W350STQ-W370ST:~/DiscosVirtuais$ lxc config device add
ol7testedisc loop24 unix-block path=/dev/loop24
Dispositivo loop24 adicionado a ol7testedisc


-- In the container:

[root at ol7testedisc ~]#lsblk
NAME   MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
sdb      8:16   0 698.7G  0 disk
`-sdb1   8:17   0 698.7G  0 part /dev/loop24
loop24   7:24   0     1G  0 loop

[root at ol7testedisc ~]# df -h
Filesystem      Size  Used Avail Use% Mounted on
/dev/sdb1       687G  109G  544G  17% /
none            492K     0  492K   0% /dev
udev            7.8G     0  7.8G   0% /dev/tty
tmpfs           100K     0  100K   0% /dev/lxd
tmpfs           100K     0  100K   0% /dev/.lxd-mounts
tmpfs           7.8G     0  7.8G   0% /dev/shm
tmpfs           7.8G  8.1M  7.8G   1% /run
tmpfs           7.8G     0  7.8G   0% /sys/fs/cgroup
tmpfs           1.6G     0  1.6G   0% /run/user/54321

[root at ol7testedisc ~]# mount -t ext4 /dev/loop24 /mnt
mount: /dev/loop24 is already mounted or /mnt busy


And im loss...






-- 
Atenciosamente,

Márcio de Figueiredo Moura e Castro


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