[Lustre-discuss] lustre and software RAID

Andreas Dilger adilger at whamcloud.com
Fri Jan 21 12:59:43 PST 2011

On 2011-01-21, at 13:36, Samuel Aparicio wrote:
> trying to create an ext4 lustre filesystem attached to an OSS.
> the disks being used are exported from an external disk enclosure.
> i create a raid10 set with mdadm from 16 2Tb disks, this part seems fine.
> I am able to format such an array with normal ext4, mount a filesytem etc.
> however when i try the same thing, trying to format for a lustre filesystem I am unable to mount the filesystem and lustre does not seem to detect it.
> the lustre format completes normally, without errors.

You are probably formatting the filesystem with an ext4 feature that is not in the ldiskfs module you are using.

> lustre version 1.8.4
> kernel 2.6.18-194.3.1.el5_lustre.1.8.4
> disk array is a coraid SATA/AOE device which has worked fine in every other context

Do you have the ext4-based ldiskfs RPM installed?  It is a separate download on the download page.  You can check whether the ldiskfs module installed was based on ext3 or ext4 with the "modinfo" command:

[root]# modinfo ldiskfs
filename:    /lib/modules/
license:     GPL
description: Fourth Extended Filesystem

author:      Remy Card, Stephen Tweedie, Andrew Morton, Andreas Dilger, Theodore Ts'o and others
srcversion:  D5D8992C8B3E6FCA6ED4FF2
vermagic: SMP mod_unload modversions 

Cheers, Andreas
Andreas Dilger 
Principal Engineer
Whamcloud, Inc.

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