[lxc-users] Can we run a container from ramfs?

[Cal Leeming [Simplicity Media Ltd]]

Seems there's a few discussions about ramfs and pivot [1], and apparently
it's unsupported [2].

As a workaround you could try to place overlayfs on top of your ramfs [3],
you'd then place both your lower and upper dir on ramfs - YMMV.

Others may chime in with a different workaround, as I'm not sure if this
would be the best way.

Hope this helps

Cal

[1] https://www.google.co.uk/search?q=pivot_root+tmpfs
[2] http://www.slax.org/blog/18438-initramfs-pivot-root-solution.html
[3] http://askubuntu.com/questions/109413/how-do-i-use-overlayfs





On Sat, Dec 14, 2013 at 7:18 AM, Qiang Huang <h.huangqiang at huawei.com>wrote:

> Hi guys,
>
> I was trying to run a container from ramfs, to root filesystem is
> rootfs(ramfs), the template is put onto a mounted disk whose fs is
> ext3, and I got this error(I'll skip my config and version and os
> and so on, I think they are not keys):
> ...
> lxc-start 1386999058.944 DEBUG    lxc_conf - mountpoint for old rootfs is
> '/usr/local/lib/lxc/rootfs/lxc_putold'
> lxc-start 1386999058.944 ERROR    lxc_conf - Invalid argument - pivot_root
> syscall failed
> lxc-start 1386999058.944 ERROR    lxc_conf - failed to setup pivot root
> lxc-start 1386999058.944 ERROR    lxc_conf - failed to set rootfs for
> 'hq91'
> lxc-start 1386999058.944 ERROR    lxc_start - failed to setup the container
> lxc-start 1386999058.944 ERROR    lxc_sync - invalid sequence number 1.
> expected 2
> lxc-start 1386999058.952 ERROR    lxc_start - failed to spawn 'hq91'
>
> I dug and figured out that pivot_root has some limitations with ramfs,
> So is it possible to run a container from ramfs? And how can we do that?
>
> Any comments are appreciated.
>
>
>
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