[Lustre-discuss] how to add force_over_8tb to MDS

Theodore Omtzigt theo at stillwater-sc.com
Thu Jul 14 11:10:13 PDT 2011


    The reason I had to do it on the OST's is because when issuing the 
mkfs.lustre command to build the OST it would error out with the message 
that I should use the force_over_8tb mount option. I was not able to 
create an OST on that device without the force_over_8tb option.

Your insights on the writeconf are excellent: good to know that 
writeconf is solid. Thank you.


On 7/14/2011 1:29 PM, Michael Barnes wrote:
> On Jul 14, 2011, at 1:15 PM, Theodore Omtzigt wrote:
>> Two part question:
>> 1- do I need to set that parameter on the MGS/MDS server as well
> No, they are different filesystems.  You shouldn't need to do this on the OSTs either.  You must be using an older lustre release.
>> 2- if yes, how do I properly add this parameter on this running Lustre
>> file system (100TB on 9 storage servers)
> covered
>> I can't resolve the ambiguity in the documentation as I can't find a
>> good explanation of the configuration log mechanism that is being
>> referenced in the man pages. The fact that the doc for --writeconf
>> states "This is very dangerous", I am hesitant to pull the trigger as
>> there is 60TB of data on this file system that I rather not lose.
> I've had no issues with writeconf.  Its nice because it shows you the old and new parameters.  Make sure that the changes that you made were the what you want, and that the old parameters that you want to keep are still in tact.  I don't remember the exact circumstances, but I've found settings were lost when doing a writeconf, and I had to explictly put these settings in tunefs.lustre command to preserve them.
> -mb
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