Re: UFS filesystem features

[Claus Assmann <dragonfly-users@xxxxxxxxx>]

On Sat, Sep 03, 2005, Matthew Dillon wrote:

>     There are two things I want for UFS:  (1) Nearly instant reboots
>     (without having to depend on softupdates), and (2) an ability to grow
>     or shrink the filesystem.  Both are quite achievable goals.

What about the logging feature from Sun? Their FS became very fast
in SunOS 5.10 (maybe also 5.9).

mount_ufs(1M):
If logging is specified, then logging is enabled for the duration
of the mounted file system. Logging is the process of storing
transactions (changes that make up a complete UFS operation) in a
log before the transactions are applied to the file system. Once a
transaction is stored, the transaction can be applied to the file
system later. This prevents file systems from becoming inconsistent,
therefore eliminating the need to run fsck. And, because fsck can
be bypassed, logging reduces the time required to reboot a system
if it crashes, or after an unclean halt.


My tests showed pretty impressive performance results (the tested
application is an MTA, i.e., lots of write(2) and fsync(2)).