[LU-11473] Add ‘lfs getsom’ to the lfs man page

• Type: Improvement
• Resolution: Fixed
• Priority: Minor
• Fix Version/s: Lustre 2.12.0
• Affects Version/s: Lustre 2.12.0
• Labels: LSOM
• Assignee: James Nunez (Inactive)
• Reporter: James Nunez (Inactive)

Description

The Lazy Size on MDT feature added the flag “getsom” to lfs that will collect lazy stat information for a file. The lfs man page needs to be updated to include this flag.

Here’s what I can gather from the LSOM test plan about ‘lfs getsom’:

The lfs getsom command lists file attributes that are stored on the MDS. lfs getsom is called with the full path and file name for a file on the Lustre file system. If no flags are used, then all file attributes stored on the MDS will be shown.

Usage: lfs getsom [-s] [-b] [-f] <path>

Flags for lfs getsom are:

Flag Description
-s Only show the size value of the SOM data for a given file. This is an optional flag.
-b Only show the blocks value of the SOM data for a given file. This is an optional flag.
-f Only show the flag value of the SOM data for a given file. This is an optional flag.
Valid flags are:
SOM_FL_UNKNOWN = 0x0000 - Unknown or no SoM data, must get size from OSTs.

SOM_FL_STRICT = 0x0001 - Known strictly correct, FLR or DoM file (SoM guaranteed).

SOM_FL_STALE = 0x0002 - Known stale - was right at some point in the past, but it is known (or likely) to be incorrect now (e.g. opened for write).

SOM_FL_LAZY = 0x0004 - Approximate, may never have been strictly correct, need to sync SOM data to achieve eventual consistency.

Issue Links

• is related to: LU-9538 Size on MDT with guarantee of eventual consistency

Comments

[Peter Jones]

Landed for 2.12

[Gerrit Updater]

Oleg Drokin ([e-mail]) merged in patch https://review.whamcloud.com/33290/
Subject: LU-11473 doc: add lfs-getsom man page
Project: fs/lustre-release
Branch: master
Current Patch Set:
Commit: 697e8fe6f325089fe2c69c56cc49bbdadd3a2c3d

[Andreas Dilger]

To be honest, I don't really think of "lfs getsom" as a user interface that most tools will use, but more for testing and debugging.

I'd really prefer that we integrate the use of the som xattr directly into tools like lfs find and via statx() so that a broad range of users can benefit.

[Gerrit Updater]

James Nunez ([e-mail]) uploaded a new patch: https://review.whamcloud.com/33290
Subject: LU-11473 doc: add lfs-getsom man page
Project: fs/lustre-release
Branch: master
Current Patch Set: 1
Commit: 97505a60766534b87d700df9179ad0e5318d95be