[lustre-discuss] OST -> MDT migration and MDT -> OST migration
adilger at whamcloud.com
Thu Apr 15 00:08:35 PDT 2021
On Apr 15, 2021, at 00:52, Åke Sandgren <ake.sandgren at hpc2n.umu.se> wrote:
>> On 4/15/21 5:12 AM, Andreas Dilger via lustre-discuss wrote:
>> On Apr 14, 2021, at 18:42, Bill Anderson via lustre-discuss
>> <lustre-discuss at lists.lustre.org
>> <mailto:lustre-discuss at lists.lustre.org>> wrote:
>>> Hi All,
>>> I'm trying to figure out how to migrate files stored on an OST to
>>> an MDT (that's using DoM) and to migrate files stored on an MDT to an
>>> OST (e.g., if the MDT is getting full). I can see how to migrate
>>> between OSTs, but not between OSTs and MDTs. I'm running Lustre 2.12.3.
>>> Do you happen to know the syntax for migration between OSTs and MDTs?
>>> Thanks for any help!
>> You just use "lfs migrate <file layout> <file>" to migrate from DoM
>> files to OST objects. However, OST-to-DoM migration isn't available
>> until 2.13.
> Couldn't you just use lfs mirror extend with a PFL that points into the
> DoM, and then a resync/split
Yes, and that's what happens in 2.13 when this functionality is
implemented. To migrate from DoM->OST you can just make a copy of
the file and swap layouts. The issue in 2.12 is that you can't write into the
MDT inode to do OST->DoM migration/mirroring.
More information about the lustre-discuss