[Lustre-discuss] recover OST data just using ./ROOT/ and ea.bak?

Aaron Knister aaron.knister at gmail.com
Mon Sep 28 18:58:08 PDT 2009


Doh! Sorry to hear about your dead mdt. I'm no expert but something  
along the lines of the following may work-

1. mke2fs -j -J size=400 -I {inode_size} -i 4096 {new mdt dev}

where {inode_size} is at least 512 and possibly larger if the default  
stripe count is > 10 (inode_size = power_of_2_>=_than(384 +  
stripe_count * 24))

	tune2fs -O dir_index {new mdt dev}

2. Mount the new mdt as ldiskfs (mount -o ldiskfs) at say /mnt/mdt

3. Restore ROOT and your eas.  (unmount the mdt)

4. Run tunefs.lustre --fsname={fsname} --mdt --mgs --writeconf {new  
mdt dev } on the new mdt

5. Shutdown all your osts

6. Run tunefs.lustre --writeconf on your osts

7. Pray to the lustre gods for mercy

8. Mount your mdt as lustre (mount -o lustre)

9. Re-mount your osts and hope for the best

Hopefully one of the lustre experts on this list will comment on the  
above with a "yep that'll work" or "you gotta be crazy to do that"

-Aaron

On Sep 28, 2009, at 1:32 PM, Matt Franks wrote:

>
>
> Ok, here's a good one...
>
> I have a lustre set up with version 1.8. Its has a combo mdt/mgs on  
> one machine and three OSSs with a couple of OSTs on each.
>
> The array that the mdt/mgs was on died and decided to stay dead,  
> taking its data with it. But, I thought, no problem I have my file  
> level backup that I did a couple of days ago. But owing to a typo in  
> the script I ran, I only got the tar and getfattr of the ROOT  
> directory, rather than the whole volume.
>
> My question to the lustre public is.. is it possible to recover the  
> data on the OSTs using this? If so, can anyone lend any pointers?  
> (If, in theory its not possible, I'll stop banging my head against  
> the wall and move on)
>
> Any advice appreciated!
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> Lustre-discuss at lists.lustre.org
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