On 08/12/2012 08:16 PM, Kevin Chadwick wrote: > It is faster with softdep and safer without. My mail client has similar > choices in it's options. Which do you think my mail client enables by > default... The safe option of course. So does OpenBSD which isn't like > Linux userspace.
Is 'safer' really the right word here? As I understand it, with or without softdeps, the filesystem on disk will be consistent and recoverable (excepting, of course, that when a disk confirms a write is completed isn't necessarily when the write is completed). The difference is that with softdeps, you don't have the guarantee that metadata writes have been completed (insofar as the kernel can know) when the syscall to change it returns. On the other hand, because predicting the state of your filesytem after a crash is a bit harder with softdep enabled, leaving it turned off by default seems like a sensible choice. The really unsafe, choice, though, is mounting async, which can lead to unrecoverable filesystems in the event of a crash. -- Matthew Weigel hacker unique & idempot . ent
