ll_decode_linkea(8)

NAME

ll_decode_linkea - display parent FIDs and name of a Lustre file

SYNOPSIS

DESCRIPTION

ll_decode_linkea decodes and prints the Lustre parent FIDs and name of a Lustre file, which are stored in the "trusted.link" attribute on MDT. This is accessible to ll_decode_linkea not only through Lustre client, but also when the MDT filesystem is mounted locally as type ldiskfs for maintenance.

The "trusted.link" extended attribute is saved when file/directory is created, and modified when renaming or hard link happens.

The parent FID is useful in case of MDT corruption. The fsck of ldiskfs can recover most of the ldiskfs hierarchy, but it might leave some files or directories under lost+found. The parent FIDs can be used to determine the right Lustre paths to move them to.

EXAMPLES

root@mdt1# cd /mnt/mdt/lost+found
root@mdt1# ll_decode_linkea #123451 #123452
#123451: count 2


    0: [0x200034021:0x2:0x0], name "file1"


    1: [0x200034021:0x1:0x0], name "file1_link"
#123452: count 1


    0: [0x200000007:0x1:0x0], name "file2"

This shows that there are 2 files in lost+found. ll_decode_linkea prints all of the parent FIDs of these files. file1 has two hard links, that is why it has two parent directories. lfs fid2path could be used to extract the paths of the parents.

Since "trusted.link" xattr is accessible on Lustre client too, ll_decode_linkea could also be used on Lustre client.

AVAILABILITY

ll_decode_linkea is part of the lustre(7) filesystem package since release 2.9.0

SEE ALSO

lfs(1), lustre(7)