In computer file systems, soft updates is an approach to maintaining disk integrity after a crash or power outage. They are an alternative to journaling file system.
Instead of duplicating metadata writes in a journal, soft updates work by tracking and enforcing metadata update dependencies. Like journaling, soft updates do not guarantee that no data will be lost, but they do make sure the filesystem is consistent.
An advantage of a file system with soft updates is that it can be mounted immediately after a crash since there is no log replay.
Soft updates were first introduced to FreeBSD by Marshall Kirk McKusick and are now available across the BSDs. Recent versions of soft updates include a journaling mechanism which eliminates the need for a background fsck after a crash.
Read more about Soft Updates: Operation
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