[HPDD-discuss] lfs migrate

Hiya, has anyone used 'lfs migrate [--block]' to live migrate lots of data? it worked ok? any hints for best usage? (how many migrates running per OST etc.) the context is that we've doubled our number of OSTs and now need to rebalance our ~1 PB of data by moving roughly 1/2 of it onto the new empty OSTs. I have yet to chat to anyone who's used 'lfs migrate' (either directly or via lfs_migrate) in production, so I'm being paranoid and looking for comforting war stories where it's been used to shift around a lot of data without problems... documentation is a bit scarce. maybe just https://jira.hpdd.intel.com/browse/LU-2445 and 'lfs help migrate'. but with --block it sounds pretty amazing. it should be able to do the rebalance live and without a downtime (with some delays to file access). we're using the latest(?) Intel Enterprise Lustre version 2.0.1.1 (which appears to be 2.5.2 based). we've heard via Intel support that 'lfs migrate' runs a verify pass, which sounds nice. cheers, robin -- Dr Robin Humble