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:
-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.