[Lustre-discuss] lustre and software RAID

Andreas Dilger adilger at whamcloud.com
Fri Jan 21 14:00:00 PST 2011

On 2011-01-21, at 14:50, Samuel Aparicio wrote:
> modinfo reports as follows. seems like the ext4 modules.
> the odd thing is that the format works when the disk array is already presented as a raid set, rather than making the raidset with mdadm on the OSS
> --------
> filename:       /lib/modules/2.6.18-194.3.1.el5_lustre.1.8.4/updates/kernel/fs/lustre-ldiskfs/ldiskfs.ko
> description:    Fourth Extended Filesystem
> ---------

After the filesystem is formatted with mkfs.lustre, you should be able to mount it directly with "mount -t ext4 /dev/md??? /mnt" and see a few files in it.

If that doesn't work then the format failed for some reason.  Providing the output of "mkfs.lustre -v {options}" would help diagnose it.

> On Jan 21, 2011, at 12:59 PM, Andreas Dilger wrote:
>> 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
>> depends:     
>> vermagic: SMP mod_unload modversions 
>> Cheers, Andreas
>> --
>> Andreas Dilger 
>> Principal Engineer
>> Whamcloud, Inc.

Cheers, Andreas
Andreas Dilger 
Principal Engineer
Whamcloud, Inc.

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