[lustre-discuss] ldiskfs / mdt size limits

[Artem Blagodarenko]

Hello Thomas,

I wanted to let you know that the maximum size of the LDISKFS backend is continuously being increased.
The 16 TB limit was set a long time ago, and the current limit for LDISKFS partition size is now 1024TB.
However, for development or non-production purposes, there is an option called "force_over_512tb" that allows us to ignore this limitation.

Please note that there is still a limit of 4G inodes per partition, but Lustre FS can scale by using more targets for data and metadata.

Best regards,
Artem Blagodarenko

From: lustre-discuss <lustre-discuss-bounces at lists.lustre.org> on behalf of Thomas Roth via lustre-discuss <lustre-discuss at lists.lustre.org>
Date: Friday, 2 February 2024 at 13:35
To: lustre-discuss at lists.lustre.org <lustre-discuss at lists.lustre.org>
Subject: [lustre-discuss] ldiskfs / mdt size limits
Hi all,

  confused  about size limits:

I distinctly remember trying to format a ~19 TB disk / LV for use as an MDT, with ldiskfs, and failing to do so: the max size for the underlying ext4 is 16 TB.
Knew that, had ignoed that, but not a problem back then - just adapted the logical volume's size.

Now I have a 24T disk, and neither mkfs.lustre nor Lustre itself have show any issues with it.
'df -h' does show the 24T, 'df -ih' shows the expected 4G of inodes.
I suppose this MDS has a lot of space for directories and stuff, or for DOM.
But why does it work in the first place? ldiskfs extends beyond all limits these days?

Regards,
Thomas

--
--------------------------------------------------------------------
Thomas Roth
Department: Informationstechnologie
Location: SB3 2.291


GSI Helmholtzzentrum für Schwerionenforschung GmbH
Planckstraße 1, 64291 Darmstadt, Germany, www.gsi.de

Commercial Register / Handelsregister: Amtsgericht Darmstadt, HRB 1528
Managing Directors / Geschäftsführung:
Professor Dr. Paolo Giubellino, Jörg Blaurock
Chairman of the Supervisory Board / Vorsitzender des GSI-Aufsichtsrats:
Ministerialdirigent Dr. Volkmar Dietz

_______________________________________________
lustre-discuss mailing list
lustre-discuss at lists.lustre.org
http://lists.lustre.org/listinfo.cgi/lustre-discuss-lustre.org
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.lustre.org/pipermail/lustre-discuss-lustre.org/attachments/20240202/f2049e8e/attachment.htm>