I should probably clarify my answer. All file systems provide writes by default which are atomic with respect to readers of the file. That's a POSIX requirement. In other words, if you're writing ABC, there's no possibility that a reader might see ABD (if D was previously contained in the file) or just AB.
POSIX doesn't provide any means to change this behaviour, but individual file systems may; I believe direct I/O on UFS might, at least for overwrites, and QFS has a specific mount option (which can also be set on an individual file) to allow concurrent readers & writers. However, when considering atomicity with respect to a system crash, my previous comments stand. (This is the type of atomicity which is important for a database log file, for instance.) This message posted from opensolaris.org _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
