[Lustre-discuss] iSCSI Integration Solutions

[Andreas Dilger]

On Sep 29, 2009  10:24 -0400, Pete Eby wrote:
> ... I want to re-export the file system from luster to other clients
> via iSCSI  - and I can't quite seem to grasp how this can be done.
> 
> > I'm starting to feel like you want lustre to be an iscsi "service".
> > That's not possible.  Lustre presents a filesystem, not storage devices.
> 
> Yea, I don't expect Luster itself to present iSCSI, but rather how take
> advantage of an presented luster FS and re-export as iSCSI.

I expect that the Linux kernel already has some sort of iSCSI target
support.  It may be possible to use this to export files from Lustre,
though the iSCSI target may depend on access to a Linux block device,
which isn't really supported by Lustre (since there are not necessarily
even disks on the Lustre clients).

You might be able to use a loop device to create a block device from
a Lustre file, and then re-export that via iSCSI.

There is also UNSUPPORTED work that was done to add a block device
interface to a Lustre file.  I don't think it works very well at the
moment, but if you have programming skills and time for testing and
development I could probably help you with debugging this code.

> It seems like this is possible, but I am missing how to bridge between
> say a Luster client, connecting to an exported Luster FS and re-offering
>  that file systems through iSCSI.

This is something that probably already exists in the Linux kernel.

Cheers, Andreas
--
Andreas Dilger
Sr. Staff Engineer, Lustre Group
Sun Microsystems of Canada, Inc.