LLSOM_SYNC(8)

NAME
llsom_sync - Utility to sync file LSOM xattr.

SYNOPSIS
llsom_sync {--mdt|-m} =MDT {--user|-u} =USER_ID [--daemonize|-d] [--verbose|-v] [--interval|-i] [--min-age|-a] [--max-cache|-c] [--sync|-s] LUSTRE_MOUNT_POINT

DESCRIPTION
llsom_sync is designed to sync file LSOM xattr in the Lustre Filesystem by using Lustre MDT changelogs. A changelog user must be registered (see lctl (8) changelog_register) before using this tool.

OPTIONS

-m, --mdt=MDT
    The metadata device which need to be synced the LSOM xattr of files. A changelog user must be registered for this device.

-u, --user=USER_ID
    The changelog user id for the above MDT device. See lctl(8) changelog_register.

--daemonize
    Daemonize the program. In daemon mode, the utility will scan, process the changelog records and sync the LSOM xattr for files periodically.

--verbose
    Produce a verbose output.

--interval
    The time interval to scan the Lustre changelog and process the log record in daemon mode.

--min-age
    The time that llsom_sync tool will not try to sync the SOM data for any files closed less than this many seconds old. The default min-age value is 600s (10 minutes).

--max-cache
    The total memory used for the FID cache which can be with a suffix [KkGgMm]. The default max-cache value is 256MB. For the parameter value < 100, it is taken as the percentage of total memory size used for the FID cache instead of the cache size.

--sync
    Sync file data to make the dirty data out of cache to ensure the blocks count is correct when update the file LSOM xattr. This option could hurt server performance significantly if thousands of fsync requests are sent.

EXAMPLES
Register a changelog consumer for MDT lustre-MDT0000:
        # cl_user=$(ssh root@mds01 lctl --device lustre-MDT0000 changelog_register -n)
        # echo $cl_user
        cl1

After perform some file operations on the Lustre Filesystem with mount point '/mnt/lustre' and the filesystem undergoes some changes, sync file LSOM xattr:
        # llsom_sync --mdt=lustre-MDT0000 --user=$cl_user --verbose /mnt/lustre

To deregister the changelog user (e.g. after this example, or if SOM updates are no longer needed):
        # ssh root@mds01 lctl --device lustre-MDT0000 changelog_deregister $cl_user

AVAILABILITY
The llsom_sync command is part of the lustre(7) filesystem package since release 2.12.0

SEE ALSO
lustre(7), lctl(8)