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[email protected] krw@att.bizzzzzzzzzzzz is offline
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Default What is journaling, if anything???

On Sun, 12 Jun 2011 00:31:07 -0400, mm wrote:

On 12 Jun 2011 01:49:00 GMT, Dbdblocker wrote:

On Sat, 11 Jun 2011 21:06:20 -0400, mm wrote:

I posted to an English ng, but their answer was writing in a journal.
Now I think I'm thinking about some machining process, journaling???
Related to bearings???

What am I thinking of?


It is what a journaling file system does before it commits data to the
hard drive.


That might be what I've been thinking about. What DOES a journaling
file system do before it commits data to the hard drive?


A journaling file system makes a "journal" of the changes to the file, makes a
copy of the file, then performs the changes. A bit is then set to indicate
the new file is now the real file and erases the "journal" and the old file.
The advantage is that "bit" change is atomic (either it happens or it doesn't
- can't be in between). That atomic write, if successful, completes the
update. If power is lost or the system crashes, you still have the old file,
uncorrupted, *and* the journal so the operation can be retried later.

Wasn't it also a way to make a channel in wood or metal?


Maybe.

Ed, I keep thinking of my records ground to dust. Rather than a better
journal, I'll try to find a better accountant.