[X4U] Journal or not

[David Ledger]

>From: Kevin Willis <res19rmg at verizon.net>
>
>Can some one give me a lay-mans description of a Journaling as it
>pertains to Mac disk formats?  Should it be used with a scratch disk
>that is used for video projects?
>
>Thanks,
>
>Kevin

When the system needs to make a change to the data on the disc that 
would make the structure invalid if it failed part way through, it 
records what it wants to do first into the journal, does it, and then 
flags the journal entry as done. The events that it journals are 
those sorts of things that, if half done, have to be fixed by Disk 
Utility. This means that after a crash the system can check the 
journal for half completed tasks and either complete them of roll the 
done part back so that the filesystem is again consistent. It doesn't 
need to search for problems except in rare circumstances. Journaling 
has no drawbacks except for a few extra disc writes. Data writes 
don't get journaled. Any significant changes to the containing 
directory will be.

David


-- 
David Ledger - Freelance Unix Sysadmin in the UK.
Chair of HPUX SysAdmin SIG of hpUG technical user group (www.hpug.org.uk)
david.ledger at ivdcs.co.uk
www.ivdcs.co.uk