6.x loosing record of free space after filesystem fills?

[Jeremy Chadwick]

On Tue, Jan 09, 2007 at 06:37:16PM +0100, Oliver Fromme wrote:
> Guy Helmer wrote:
>  > I think we've finally found the cause of the problem - it wasn't just 
>  > occurring after heavy use, but was visible right after filesystem 
>  > creation!  We regularly built new filesystems with "newfs -U -O 1 -b 
>  > 65536 -f 8192"
> 
> Why are you using those blocksize and fragsize settings?
> (If you store large files, then you should at least also
> decrease the inode density, using the -i option.)

Hmm... that begs the question: how do newfs -i and tunefs -f
associate with one another?

> Some time ago, Joe Greco wrote:
>  > > the one unusual thing about the configuration is that the filesystem
>  > > we are attempting to build on is a 136GB ccd across 4 scsi disks with
>  > > the fsize=8192 and the bsize=65536 (it is mainly to be used for large
>  > > data log files):
>  > 
>  > FreeBSD doesn't support fsize/bsize so large.  There are ongoing issues
>  > within the filesystem code and VM code that will cause such filesystems
>  > to break under heavy load.  Matt Dillon also talked about this being less-
>  > than-optimal for the VM system from some technical points of view.
> 
> It has been a while, and I'm not sure if there are still
> problems with those non-standard fsize/bsize settings, but
> I would definitely try to avoid them for production use.
> 
> Best regards
>    Oliver

Shouldn't we document this somewhere?  Some places I can think
of, off the top of my head:

  * newfs(8) manpage
  * http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/configtuning-disk.html
  * http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/install-steps.html
    (this is debatable)

If we need PRs + patches for this, I'll be more than happy to
submit them.

-- 
| Jeremy Chadwick                                 jdc at parodius.com |
| Parodius Networking                        http://www.parodius.com/ |
| UNIX Systems Administrator                   Mountain View, CA, USA |
| Making life hard for others since 1977.               PGP: 4BD6C0CB |