[Lustre-devel] Moving ldiskfs external to the Lustre tree

Andreas Dilger adilger at whamcloud.com
Thu Oct 13 20:09:59 PDT 2011

On 2011-10-13, at 9:41 AM, Prakash Surya <surya1 at llnl.gov> wrote:
> On Wed, Oct 12, 2011 at 07:05:51PM -0700, Andreas Dilger wrote:
>> I'm not against this in principle, but I think it may be more difficult to actually implement before the OSD changes from Orion are landed to master.  In the past we also thought about making ldiskfs as a separate package, before ext4 started in the kernel. 
>> I've seen Prakash working on those patches but will not have time to look at them until at least next week. 
>> Are those patches against the master branch or against Orion?  Also, what kernels are supported?
> The patches for Lustre are against master. I believe our plan is to
> have the patches landed and working on master, before we officially
> integrate them into Orion.
> As far as supported kernels, I've tried to keep that consistent with
> what is already supported; although I admit most testing so far has
> been done on RHEL.
> What kernels are officially supported by Whamcloud? What kernels does it
> need to support?

So far we only support servers with RHEL-like kernels, but I've also seen patches for SLES kernels submitted, so I don't want to rule those out.

Like I previously wrote, I'm not against the patches in principle, but I haven't had a chance to look at the changes themselves yet since I'm on vacation and not supposed to be working...

Have you had the ldiskfs module externally working for a while?  How much effort is it to coordinate changes in ldiskfs (exports, API changes, etc) with Lustre?

Cheers, Andreas
>> On 2011-10-12, at 3:44 PM, "Christopher J. Morrone" <morrone2 at llnl.gov> wrote:
>>> We would like to see the ldiskfs tree removed from the lustre tree and 
>>> made an independent package.  I have been floating this idea 
>>> unofficially for a while, but I would like to now officially propose 
>>> this for Lustre 2.2.
>>> With the OBD changes that are taking place on the Orion branch, we want 
>>> to make lustre be able to use any of a number of backend filesystems. 
>>> The current tree and configure tools make it very hard to build without 
>>> ldiskfs (instead using zfs, btrfs, or something we haven't thought of 
>>> yet).  As part of cleaning that up, moving ldiskfs external to lustre 
>>> will help ensure that we don't have unnecessary dependencies crop up in 
>>> the future.
>>> We have created an external package of the ldiskfs tree and put it up on 
>>> github:
>>> https://github.com/chaos/ldiskfs
>>> To use the new external ldiskfs package with lustre, you will also need 
>>> a few patches to lustre itself.  There are links to the patches in this 
>>> jira ticket:
>>> http://jira.whamcloud.com/browse/LU-723
>>> On a RHEL system, ldiskfs has a build dependency on the kernel-debuginfo 
>>> packages by default.  That is where we find the ext4 source code.
>>> Building should be fairly straight forward.  Build and install ldiskfs 
>>> (in particular the lustre-ldiskfs-devel package), and then build lustre. 
>>> The main new change to lustre is the addition of the configure option 
>>> "--with-ldiskfs-devel".  On a RHEL system if you have the 
>>> lustre-ldiskfs-devel package installed, you won't need to give a path.
>>> Note that we have not yet removed the in-tree ldiskfs.  Our first step 
>>> was to get this working.  Once this is accepted, we will be happy to 
>>> submit the patches to remove lustre's copy of ldiskfs and generally 
>>> clean up lustre's autoconf checks involving ldiskfs.
>>> We attempted to keep the changes minimal, so we didn't change the name 
>>> of the ldiskfs rpm packages.  But we think is would be nice to change 
>>> the name from "lustre-ldiskfs" to simply "ldiskfs".  If we want to make 
>>> that change, now is the time to do it.
>>> Chris
>>> _______________________________________________
>>> Lustre-devel mailing list
>>> Lustre-devel at lists.lustre.org
>>> http://lists.lustre.org/mailman/listinfo/lustre-devel
>> _______________________________________________
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> -- 
> Cheers,
> Prakash
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