Recommendations for newfs parameters for UFS2 ?

2004-01-27 Thread Heinrich Rebehn
Hi list,

Are there any recommendations for the blocksize, bytes/i-node, and
cylinders/group parameters when newfs'ing an UFS2 filesystem?
I am afraid of ending up with a fs with Gigs of space and no inodes 
left, or a fs that is heavily fragmented and slow.

Which params should i use for a
- 10G
- 100G
- 500G
filesystem?

I read man(7) tuning but would like to hear about some real experiences.

Thanks very much for your help!

Heinrich
--
Heinrich Rebehn

University of Bremen
Physics / Electrical and Electronics Engineering
- Department of Telecommunications -
Phone : +49/421/218-4664
Fax   :-3341
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Re: Recommendations for newfs parameters for UFS2 ?

2004-01-27 Thread Matthew Seaman
On Tue, Jan 27, 2004 at 02:09:29PM +0100, Heinrich Rebehn wrote:
 Hi list,
 
 Are there any recommendations for the blocksize, bytes/i-node, and
 cylinders/group parameters when newfs'ing an UFS2 filesystem?
 
 I am afraid of ending up with a fs with Gigs of space and no inodes 
 left, or a fs that is heavily fragmented and slow.
 
 Which params should i use for a
 - 10G
 - 100G
 - 500G
 
 filesystem?
 
 I read man(7) tuning but would like to hear about some real experiences.

The parameters given to newfs(8) don't depend on the size of the
filesystem, so much as the size of the files you intend to store
within it, and the sort of directory structure you want to use
(ie. how many files per directory) Many of the tunables in newfs(8) to
do with the details of disk geometry don't make sense with modern
drives and should be ignored.

You should try running 'newfs -N' with various values for the '-g'
average file size and '-h' average numbers of files per directory
parameters to see what sort of numbers it spits out.  You don't have
to be too accurate with those file size and files per directory
estimates -- order of magnitude is generally good enough.  Unless
you're going to be storing exceptionally large files (say, typical
size 20Mb) or you want to have directories with 5,000 or more files in
them, then just using the newfs(8) default values will work very well.

One thing you can do for any file system over about 256Mb is drop the
free space reserve ('-m' option in newfs(8), or it can be modified in
an existing filesystem using tunefs(8)).  1% is more than adequate if
you're creating a multi-gigabyte filesystem.

Cheers,

Matthew

-- 
Dr Matthew J Seaman MA, D.Phil.   26 The Paddocks
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PGP: http://www.infracaninophile.co.uk/pgpkey Marlow
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