:
:In message <[EMAIL PROTECTED]>,
:Charles Randall writes:
:>The qmail FAQ specifically recommends against soft updates for the mail
:>queue.
:>
:>http://cr.yp.to/qmail/faq/reliability.html#filesystems
:>
:>Is this incorrect?
:>
:
:It seems to indicate that qmail doesn't use fsync(2) as much as it should
:do. If that is true, then yes, softupdates would mean that a lot of things
:which qmail (mistakenly) think has been written are in fact not on the
:disk.
:
:--
:Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
:[EMAIL PROTECTED] | TCP/IP since RFC 956
:FreeBSD committer | BSD since 4.3-tahoe
:Never attribute to malice what can adequately be explained by incompetence.
QMail's FAQ is totally incorrect. No major filesystem -- be it
FFS, EX2FS, Reiser, FFS+Softupdates, guarentees that when you
write() and close() a file that the file will then survive a disk
crash. All these filesystems guarentee is that if a crash occurs,
when the system reboots the filesystems will be recovered into a
consistent state. Softupdates is considerably better at guarenteeing
this consistency (as is something like Reiser), but if you crash a
softupdates disk may wind up unwinding 'more' of the last few moments
worth of operations then a normal filesystem would. And, I might add,
Reiser is the same way.
The only way to guarentee that file data is written to disk, with any
filesystem no matter how it is mounted (even sync mounted filesystems),
is by calling fsync().
So I would stick with softupdates.
-Matt
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