durability

What survives a crash or power loss during a copy or a move.

Copy

A copy does not call fsync, like cp: the kernel writes the data back in its own time. A copy only reads its sources, so a crash during a copy never touches them. Copy still never shows a partial file under its real name while it runs; see file operations.

Move

A move keeps every file in at least one complete, committed place at every moment. That also holds after a crash or power loss, on filesystems that honour syncfs: btrfs, ext4 and xfs.

A cross-filesystem move works in batches of 256 files or 256 MiB. After each batch, manycommander flushes the destination filesystem with syncfs and only then deletes that batch's sources. After a crash, the last unflushed batch can be in both places, never in neither. Run F6 again to merge the rest.

Leftovers

After a crash, .mc-partial-* files can remain in a destination directory. They are incomplete copies. manycommander never deletes them automatically; remove them by hand once you have checked the source.