[Lxc-users] usb devices

[Nirmal Guhan]

On Mon, Aug 2, 2010 at 6:07 PM, Toby Corkindale
<toby.corkindale at strategicdata.com.au> wrote:
> On 03/08/10 09:04, Nirmal Guhan wrote:
>> Hi,
>>
>> Am running fedora 12 with 2.6.32.10-90.fc12.i686 kernel. Currently I
>> use bind mount to access usb disks. For instance :
>>
>> /media /lxc/f12/usbdisk none bind 0 0
>>
>> udev mounts usb devices on /media. There are some issues with this approach :
>>
>> 1) Since this is hard coded config, it has to be updated everytime the
>> mount point (/media in this case) changes.
>> 2) If I unmount /media from the host, the container can still access
>> the disk from /usbdisk i.e ls /usbdisk and other operations work
>> within container but not /media from the host. How is this possible ?
>> 3)  By #2, I assume there is some sort of usb pass-through within
>> container? Is this true ?
>
> No, it's not true. There is no special USB pass-thru to the container.
>
> By making a bind-mount, you are replicating part of the filesystem so
> that it is inside the bit of the filesystem that LXC is using.
> This is done at the filesystem level - not at the USB level.
>
> This explains why you can still access it after unmounting at the host
> level. You have effectively mounted it twice, so it needs to be
> unmounted from both locations too.

Ah! yes. Good catch.

>
>> 4) Hot swap does not work within the container. After usb device is
>> reinserted, container cannot recognize it but host can.
>> 5) "mount" within the container  always displays just one single line
>> while I have few more in fstab including the above /media stuff.
>>       none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw)
>
> Again, that's because of the way LXC works with the filesystem.
>
> Perhaps you could just bind-mount the whole /media directory into the
> guest containers, to their /media directory? That might work better for
> you, although still not quite what you want.

Thanks Toby. I doubt if this will address #1 and #4 above. Basically,
how to make hot swap work? Or what are the workaround to get
notifications if I have to manually mount/umount.

>
>
> -Toby
>
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