[Openstack] Essex: LXC volume attachment does not work?

David Kang dkang at isi.edu
Tue Jun 5 22:38:11 UTC 2012


 Hello,

 We are using Essex version.
We are testing volume attachment to an LXC instance.
>From the code, the volume is mounted by the host machine to the file system of the LXC instance.

# nova/virt/disk/api.py
utils.execute('mount', '-o', 'bind', src, target,
                run_as_root=True)

>From the host machine, it is visible.
But, inside of the LXC instance, it is not visible.
Does this method work?

 Before Essex, we used "lxc-attach" command to run "mknod" command inside of the LXC instance
instead of "mount" it by the host outside of the LXC instance.
It did work.

 Here are the content of the dev directory shown inside of the LXC instance, and at the host side.
Both are different. And dynamic changes done by the host outside of the LXC instance is not shown inside of the LXC instance.
Is our LXC configuration or our LXC image is wrong?

1. Inside the LXC instance 
$ ls /dev
console  full  null  nvidia0  nvidia1  nvidia2  nvidia3  nvidiactl  ptmx  pts  random  tty  tty1  urandom  zero

2. At the host
$ ls /usr/local/nova/instances/instance-0000004f/rootfs/dev/
block            crash  full       kmsg   loop5    mapper  nbd13  nbd7                oldmem  ram11  ram5    rtc   sg2  shm       tty0   tty16  tty23  tty30  tty38  tty45  tty52  tty6   ttyS0    usbmon3  vcs2   vcsa3        zero
bsg              disk   fuse       kvm    loop6    mcelog  nbd14  nbd8                port    ram12  ram6    rtc0  sg3  snapshot  tty1   tty17  tty24  tty31  tty39  tty46  tty53  tty60  ttyS1    usbmon4  vcs3   vcsa4
bus              dm-0   fw0        log    loop7    mem     nbd15  nbd9                ppp     ram13  ram7    sda   sg4  snd       tty10  tty18  tty25  tty32  tty4   tty47  tty54  tty61  ttyS2    usbmon5  vcs4   vcsa5
char             dm-1   hidraw0    loop0  lp0      nbd0    nbd2   net                 ptmx    ram14  ram8    sda1  sg5  stderr    tty11  tty19  tty26  tty33  tty40  tty48  tty55  tty62  ttyS3    usbmon6  vcs5   vcsa6
console          dm-2   hidraw1    loop1  lp1      nbd1    nbd3   network_latency     pts     ram15  ram9    sdb   sg6  stdin     tty12  tty2   tty27  tty34  tty41  tty49  tty56  tty63  urandom  usbmon7  vcs6   vdc
core             fb     hugepages  loop2  lp2      nbd10   nbd4   network_throughput  ram0    ram2   random  sdb1  sg7  stdout    tty13  tty20  tty28  tty35  tty42  tty5   tty57  tty7   usbmon0  usbmon8  vcsa   vga_arbiter
cpu              fb0    hvc0       loop3  lp3      nbd11   nbd5   null                ram1    ram3   raw     sg0   sg8  systty    tty14  tty21  tty29  tty36  tty43  tty50  tty58  tty8   usbmon1  vcs      vcsa1  vhost-net
cpu_dma_latency  fd     input      loop4  MAKEDEV  nbd12   nbd6   nvram               ram10   ram4   root    sg1   sg9  tty       tty15  tty22  tty3   tty37  tty44  tty51  tty59  tty9   usbmon2  vcs1     vcsa2  VolGroup

 Thanks,
 David

----------------------
Dr. Dong-In "David" Kang
Computer Scientist
USC/ISI




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