[SunHELP] UFS logging worth it?
sunhelp at sunhelp.org
Tue Nov 21 07:30:19 CST 2000
On Tue, Nov 21, 2000 at 02:21:59PM +0100, Magnus Abrante wrote:
> Let me correct my previous message, if you dont have the logging
> turned on in the /etc/vfstab, the file system wont know that it is
> a logging filesystem upon reboot, thus it wont be using the logs
> for the fcsk. So if you just did a remount and turned on the logging
> feature without adding it to /etc/vfstab i dont think it will work.
Yep, I've got all my ufs filesystems with "logging" under options in
>From the mount_ufs manual page:
logging | nologging
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 sys-
tem later. This prevents file systems from
becoming inconsistent, therefore eliminat-
ing 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. The
default behavior is nologging.
The log is allocated from free blocks on
the file system, and is sized approximately
1 Mbyte per 1 Gbyte of file system, up to a
maximum of 64 Mbytes. Logging can be
enabled on any UFS, including root (/).
The log created by UFS logging is continu-
ally flushed as it fills up. The log is
totally flushed when the file system is
unmounted or as a result of the lockfs -f
so far, I see no evidence of the "This prevents file systems from
becoming inconsistent, therefore eliminating the need to run fsck."
I see slight differences in some things, like "rm -rf" of a large
source tree returns a prompt instantly, but other than that, I see
no advantages to using UFS logging, as it appears to not function
as per the manual page says it should...
If only VxFS (Veritas Filesystem) was cheaper... 8-(
mrbill at mrbill.net
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