Re: Patches for journalling support

[Michael Lorenz <macallan%netbsd.org@localhost>]

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Hello,

On Mar 2, 2008, at 07:05, Simon Burge wrote:

> Currently WAPBL uses space after the filesystem (but before the
> partition's end) for its journal.  The suggested method is to use:
>
>         newfs -s -64m <other options> /dev/<foo>
>
> to leave 64MB of space for the journal.  Obviously this will destroy
> any existing data in the filesystem on /dev/<foo> and you should, of
> course, back up any data on this filesystem first.  The journal size
> itself is still the subject of some research.  Solaris uses "10% of
> filesystem size to a maximum of 64MB", and at Wasabi we've always used
> a 64MB journal on larger filesystems.

Hmm, I remember AIX using a 16MB partition for journalling data from  
a whole volume group - several filesystems spread out on several  
disks, in my case about 80GB total. And it was a 16MB partition  
because that's the smallest unit the volume manager could assign to a  
logical volume. So, is the 64MB figure based on experience, design or  
just a random number that happens to work well?

have fun
Michael

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