[LU-7607] Preserve inode number after MDT migration

• Type: Improvement
• Resolution: Unresolved
• Priority: Minor
• Affects Version/s: Lustre 2.8.0
• Labels: dne3
• Epic Link: MDT rebalance v3
• Assignee: Lai Siyao
• Reporter: Andreas Dilger

Description

During migration, the MDT FID of the migrated file is changed to reflect the new MDT the inode is stored on. However, it would be possible to keep the user-visible inode constant after migration by storing the original FID into the LMA as a new field. If present, this saved FID could be used to generate the inode number for userspace instead of the current FID so that it doesn't affect user tools such as backups.

Issue Links

• is related to: LU-17818 LMR: Lustre Metadata Redundancy
• is related to: LU-7749 DNE3: migrated orphan survive till next reboot
• is related to: LU-14465 unlink fails when if the metadata migration is running behind
• is related to: LU-11753 MDS BUG on lfs migrate [osd_it_ea_rec]
• is related to: LU-11306 Moving files from one MDT to another does not free inodes on source MDT
• is related to: LU-11025 DNE3: directory restripe
• is related to: LU-17820 LMR1b: Replicate ROOT/ and Top-level Directories
• is related to: LU-6866 MDT file migration is incompatible with HSM
• is related to: LU-2430 Migration tool for DNE
• is related to: LU-13426 "lfs migrate" on DoM component clobbers LOV EA FID
• is related to: LU-14975 DNE3: directory migration in non-recursive mode