>>> On Wed, 29 Aug 2007 14:39:31 -0400, "Justin Bronder"
>>> <[EMAIL PROTECTED]> said:
[ ... using 'nointegrity' to disable journaling ... ]
jsbronder> a.) Mount the filesystem with nointegrity and leave
jsbronder> it like that. If the file has been opened, written
jsbronder> to, and closed, do we stand to lose anything should a
jsbronder> power loss happen later?
I have seen the reply by DavidK, and let me add that this
question is a bit fuzzy as for example in "lose anything".
Perhaps this question is based on the illusion that JFS journals
data as well as metadata, because even with 'integrity' if there
is some interruption before all data has been written to platter,
bad news, and 'close' means fairly little.
My understanding is that all that 'nointegrity' does is skip the
journaling for metadata, and even with 'integrity' metadata is not
written synchronously to the journal.
Also, caching and journaling, of data or metadata, are relevant
not just if "power loss" happens but also in case of kernel crash,
hardware failure etc.
Perhaps it would be helpful to look at
* 'man 2 fsync', 'man 2 fdatasync';
* 'man 2 open' and 'O_SYNC', 'O_DSYNC' and 'O_RSYNC';
* 'man 8 mount' and the 'sync' or 'dirsync' options;
* 'man 8 mount' and the 'commit' option for 'ext3';
* 'dirty_expire_centisecs' and 'dirty_writeback_centisecs'
in '/proc/sys/vm' ('Documentation/filesystems/proc.txt'
is where they are explained in the kernel source tree).
Also note that there are several threads over the decades in
'comp.arch' and 'comp.arch.storage' discussing disk and fsys
caching and journaling semantics, and things are subtle...
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