[lxc-users] loading a file system

[Fajar A. Nugraha]

Containers can see any host mount point if specifically bind-mounted
to the container, e.g. via lxc.mount.entry. I haven't seen a way to
add new mount points to the container after it's started though.

-- 
Fajar

On Wed, Jan 14, 2015 at 3:21 PM, Mohan G <mohan_gg at yahoo.com> wrote:
> Also, i am hoping that all host mount point can be seen by containers. Is
> this assumption correct.
>
>
> On Wednesday, January 14, 2015 1:47 PM, Mohan G <mohan_gg at yahoo.com> wrote:
>
>
> Thanks for the replies. My conclusions from the replies are that i am better
> of controlling the consumers of my FS via cgroups. If i decide to run my
> apps on containers, then i need to mount my FS on the host and create
> containers with limits of CPU and memory and use my FS via this container.
> Both these approaches seem fine and helps.
>
>
>
>
>
> On Wednesday, January 14, 2015 12:28 PM, Fajar A. Nugraha <list at fajar.net>
> wrote:
>
>
> As Serge said, some limits needs to be enforced by your filesystem.
> Like tmpfs case for example, the size limit are set during mount,
> which should be done by the host (e.g. as an option on lxc.mount.entry
> in container config file).
>
> cgroup limits is AFAIK only apply to userland, and does not apply to
> memory used by kernel modules.
>
> What is your fs like? Most fs that I know of (e.g. btrfs, ext4) does
> not need particular amount of memory/cpu resource. In this case the
> only cpu/memory limit you need to worry about are userland (handled by
> cgroups).
>
> This is different from zfs, which requires huge amount of memory. But
> even in this case the resource used are global, and can't be separated
> per pool/dataset/mountpoint, so you won't be able to limit it per
> container.
>
> fuse, on the otherhand, will use some cpu/memory resource per mounts
> on its userland part. In this case, you can limit its cpu/memory usage
> the same way you limit other userland processes, using cgroups.
>
> --
> Fajar
>
>
> On Wed, Jan 14, 2015 at 12:25 PM, Mohan G <mohan_gg at yahoo.com> wrote:
>> Thanks. When i say my own file system, yes my own kernel file system
>> written
>> for linux. A small yet working FS.
>> I want to load this FS and want applications to use them, but not consume
>> entire cpu and memory. If i can bring up KVM then i can set cpu and memory
>> for this KVM and load and mount my FS in this KVM and KVM's resource
>> limits
>> will directly control the FS consumption etc.
>>
>> How i can achieve the same thing without using KVM. When i mean template,
>> i
>> mean the linux image used as a separate container. ( i assume i can build
>> a
>> new linux distro with my FS as default) and boot it up.
>> I am aware that containers are user level and share the same kernel. Thank
>> for the patience
>>
>>
>>
>> On Wednesday, January 14, 2015 10:37 AM, Fajar A. Nugraha <list at fajar.net>
>> wrote:
>>
>>
>> You need to be more clear. More response inline
>>
>> On Wed, Jan 14, 2015 at 11:26 AM, Mohan G <mohan_gg at yahoo.com> wrote:
>>>
>>> Thanks for the reply, now i guess my specific question is.
>>> 1) I have my own file system which i can load to the kernel. But i want
>>> to
>>> restrict the file systems usage as a whole.
>>
>> Do you mean your own file system module? e.g. something like fuse?
>> What do you mean by "restrict the file systems usage"? Only some
>> container can use that type of fs? Restrict its size?
>>
>> Short version is you should set all mounts in the host (including
>> loading the fs module, if it's a new one), and the container can then
>> simply use it. Also, do NOT allow containers to mount their own
>> filesystem (this is already the default setting when you use ubuntu
>> container on ubuntu host)
>>
>>
>>> 2) which means if i can build a kernel template with my FS on it , then
>>> would i be able to set limits on memory and cpu for the FS.
>>>
>>
>> what "kernel template"? You DO know that containers share the same
>> kernel as the host, right?
>> Also, I see no direct connection between "memory and cpu" and the type
>> of filesystem. Are you perhaps confusing FS, when you mean "container"
>> (i.e. guest)
>>
>>> basically i am looking for ways for FS to use KVM type limit ( in terms
>>> of
>>> cpu and memory) without actually using KVM.
>>
>> If you mean "limit container's cpu and memory use", see earlier
>> response about cgroups. Again, I see no correlation between FS and
>>
>> "cpu and memory".
>>
>>
>> --
>> Fajar
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