Greetings to One and All! I am looking at the lfs_migrate command to move files among OST's in a file system. In "Lustre Software Release 2.x Operations Manual" Section 33.2.2 Description of lfs_migrate it indicates that "Because lfs_migrate is not closely integrated with the MDS, it cannot determine whether a file is currently open and/or in-use by other applications or nodes. This makes it UNSAFE (capitalized in Manual) for use on files that might be modified by other applications, since the migrated file is only a copy of the current file. This results in the old file becoming an open-unlinked file and any modifications to that file are lost."
All of the lfs_migrate examples show the command being run on an active/mounted Lustre file system. Is there any way in which one knows whether a rebalanced/migrated file was in-use at the time of migration (or that it was not in-use at the time of migration)? On a mounted Lustre FS, is it necessary to make the file system or directories therein read-only for the migration activity? Would this trait of lfs_migrate being unable to determine whether the file scheduled to be migrated is or is not in-use pose an issue if new OST's are added to the file system and lfs_migrate command is issued (rather than wait for Lustre to re-balance the load over new OSTs by attrition, as it were)? TIA for the clarifications. Still learning.... megan
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