Subject: Re: tuning TB RAID-backed filestore to reduce inode/superblock overhead
To: George Michaelson <>
From: Luke Mewburn <>
List: current-users
Date: 09/07/2004 12:06:32
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On Tue, Sep 07, 2004 at 11:36:38AM +1000, George Michaelson wrote:
  | Is there a HOWTO for BSD which explains what is 'reasonable'
  | overhead to work towards in constructing a 1.5Tb filestore on RAID?
  | A co-worker just complained the consumed space for 1.5tb looked to
  | be 100Gb and that seems a very high overhead. -no tunefs, no newfs
  | options, no RAID tuning. Out of the box.

That sounds rather high.

  | Any simple guidance would be appreciated.

It depends on how many files (inodes) that you expect to store on=20
the volume.

You can gain more space back by increasing:
	-b	block size
	-f	frag size
	-i	bytes per inode
and by decreasing the
	-m	free space %

You can also get an idea of the metadata overhead of the cylinder
groups and inodes by newfs'ing a file (newfs -F -s somesize ...)
and du-ing the result.  Don't forget to rm the test file between
runs.  (Just don't use -Z to pre-zero all blocks during testing :)


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