Dom Mitchell writes:
> A point to note here: the modern BSDs have softupdates technology
> from Kirk McKusick, which is substantially faster at create/delete
> operations. It's almost as quick as an async filesystem.
softupdates _is_ an async filesystem.
Its advantage over the Linux filesystem is that it keeps track of the
order in which to write blocks to disk, so that---just like the original
FFS---it can always put the filesystem into a consistent state after a
crash. ``Consistent'' does not mean ``up to date''!
Today's MTAs require filesystems with synchronous directory operations.
If you run them on a softupdates filesystem or on a Linux filesystem,
and your machine crashes at the wrong moment, you will lose mail.
The good news is that there are synchronous filesystems that support
many more writes per second than FFS. The bad news is that your computer
almost certainly doesn't have the necessary software.
---Dan
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