[Lustre-discuss] [wc-discuss] joining two differents mgs in one

[Andreas Dilger]

On 2012-06-29, at 1:13 PM, Tim Carlson wrote:
> This isn't really what he wants to do is it? I think he wants to what
> what is more or less impossible and that is take four distinct file
> systems and magically merge the meta data into a cohesive single
> MGS/MDS while retaining all the data.

No, I think Nathan had it right.  At least the question that was asked
was about merging the MGS (configuration management server), not the MDS
(the metadata server).

Note that it isn't strictly necessary to have a single MGS per site, and
some systems (e.g. LLNL) run a separate MGS for each filesystem, if there
are separate MDS servers for each.  In the below question, it appears that
there will be a single MDS node serving multiple MDTs (which is fine), but
this DOES require a single MGS for that node.

It makes the most sense to copy all of the MGS configs onto a separate
"MGT" filesystem, since a shared MGS on one of the MDT filesystems will
make starting/stopping individual filesystems quite difficult.  The MGS
could then run on the backup MDS node, since it is getting added recovery
functionality in 2.2 that makes it desirable to keep on a separate node
from the MDS.

> Like I currently have /a and /b  that use  MGS1 and /c and /d that use
> MGS2. How can I combine MGS1 and MGS2 into MGS3 and retain the data of
> /a /b /c /d?
> 
> Tim
> 
> On Fri, Jun 29, 2012 at 10:28 AM, Nathan Rutman
> <nathan_rutman at xyratex.com> wrote:
>> Two ways I can think of:
>> 1. mount the MGS disks as ldiskfs and copy the config files from the old MGS to the new, and point all the servers to use the new MGS ipaddr with tunefs
>> 2. writeconf all the servers, setting mgsnode as the new one.  This will regenerate all the config files on the new MGS.
>> 
>> On Jun 28, 2012, at 9:12 PM, Philippe Weill wrote:
>> 
>>> Hello
>>> 
>>> for moment and for historic reason we have four lustre filesystem on two different mgs-mds
>>> each mgs-mds having two filesystems ( 1.8.7wc1 )
>>> 
>>> we want to change our mgs-mds infrastructure ( new hardware )
>>> and keeping only one mgs and mds server for all the filesystem
>>> 
>>> I know how to move mdt on new hardware and changing IP
>>> but how can we join the two distinct mgs device in one
>>> 
>>> Thanks in advance
>>> --
>>> Weill Philippe -  Administrateur Systeme et Reseaux
>>> CNRS/UPMC/IPSL   LATMOS (UMR 8190)
>>> 
>> 


Cheers, Andreas
--
Andreas Dilger                       Whamcloud, Inc.
Principal Lustre Engineer            http://www.whamcloud.com/