Re: [OSR-devel] GlusterFS Support

[Marc G. <gr...@at...>]

Hi Gordan,

On Thursday 20 November 2008 21:10:43 Gordan Bobic wrote:
> Hi,
>
> I'm working on adding GlusterFS support for OSR. I know I mentioned this
> months ago, but I've waited until glusterfs is actually stable enough to
> use in production (well, stable enough for me, anyway).
;-)
>
> The client-only case will be simple enough, but for a
> client-with-local-storage case, it's a bit more complicated. GlusterFS
> uses a local file system as backing storage. That means that it needs to
> mount a local ext3 file system before mounting the glusterfs volume via
> fuse on top and chroots into it for the 2nd stage boot.
>
> So, I can use the <rootvolume> entry for the glusterfs part, but before
> mounting that as the rootfs, I first have to mount the underlying ext3
> file system as stage 1.5 rootfs.
>
> I'm currently thinking of implementing it by having <chrootenv> contain
> the glusterfs backing store. This would be fine as long as the
> <chrootenv> volume can be considered clobber-safe (i.e. extracting the
> initrd to it won't ever wipe the path (e.g. /gluster/ ) not contained
> within the initrd file structure.
>
> 1) Does this sound like a reasonable way to do it?
Hmm. I don't like the idea of using the chroot environment in way it is not 
expected to be used.
>
> 2) Is it safe to assume that chrootenv won't get silently clobbered? I
> know it doesn't seem to happen, but I'm still a little nervous about it...
I agree although I don't think it will be clobbered.
But why not go this way:
There is a method/function "clusterfs_services_start" which itself calls 
${clutype}_services_start which should be implemented by 
etc/${rootfs}-lib.sh. Your $rootfs should be glusterfs and therefore there 
should be a library glusterfs-lib.sh. The function clusterfs_services_start 
should do all the preparations to mount the clusterfilesystem and could also 
mount a local filesystem as a prerequisite. So I would put it there.
A rootfs can be specified as follows:
<rootvolume name="/dev/whicheverdeviceyoulike" fstype="glusterfs"/>

What do you think?

Marc.

-- 
Gruss / Regards,

Marc Grimme
http://www.atix.de/               http://www.open-sharedroot.org/