LL_DECODE_LINKEA(8)

✨ LL_DECODE_LINKEA ✨

okay bestie, gather round, because ll_decode_linkea is a lil utility from the Lustre Configuration Utilities crew and it is lowkey iconic 💅

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🌸 NAME 🌸

ll_decode_linkea — show the parent FIDs and the name of a Lustre file 🫶

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🎀 SYNOPSIS 🎀

ll_decode_linkea FILE [FILE...]

like, you give it a file, or a whole stack of files, she does not care, she's ready ✨

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🦋 DESCRIPTION 🦋

so ll_decode_linkea decodes and prints the Lustre parent FIDs and name of a Lustre file, and those lil guys are living inside the trusted.link attribute on the MDT. and the way you can get to them is not just through a Lustre client — nope — you can also reach them when the MDT filesystem is mounted locally as type ldiskfs for maintenance. two lanes, one slay 💅

that trusted.link extended attribute gets saved the moment the file or directory is created, and then it gets modified when a rename or a hard link happens. so yeah, she keeps receipts 👑

and why do we care about the parent FID?? because MDT corruption is real and it is NOT cute 😭. fsck of ldiskfs can recover most of the ldiskfs hierarchy, but sometimes it just leaves files or directories chillin' in lost+found with no explanation. and that's where the parent FIDs come in — you use them to determine the right Lustre paths to move those poor lil guys back to 🥺

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🌈 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"

so what is this telling us?? it's saying there are 2 files in lost+found. ll_decode_linkea prints out all of the parent FIDs of these files, every single one, no gatekeeping. and file1 has two hard links, which is literally why it has two parent directories — main character behavior honestly. and if you wanna go extract the actual paths of those parents, lfs fid2path is the one you call 💖

and also!! since the trusted.link xattr is accessible on a Lustre client too, ll_decode_linkea could also be used right there on the Lustre client. convenient much?? ✨

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👑 AVAILABILITY 👑

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

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💜 SEE ALSO 💜

• lfs(1)
• lustre(7)

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and that's the whole vibe, bestie 🦋 this page is from the Lustre manual set, dated 2024-08-28, and we are obsessed 💖 periodt ✨