Re: bin/41439: [dM] undocumented newfs failure

[David Laight <david%l8s.co.uk@localhost>]

The following reply was made to PR bin/41439; it has been noted by GNATS.

From: David Laight <david%l8s.co.uk@localhost>
To: gnats-bugs%NetBSD.org@localhost
Cc: 
Subject: Re: bin/41439: [dM] undocumented newfs failure
Date: Sat, 16 May 2009 13:17:51 +0100

 On Sat, May 16, 2009 at 12:00:08PM +0000, der Mouse wrote:
 > Subject: Re: bin/41439: [dM] undocumented newfs failure
 ...
 >  And, yes, -n works - or, at least, it doesn't fail; it uses only one
 >  block of inodes per cg, but way more cgs than I'd like:
 >  
 >  # newfs -b 65536 -f 8192 -n 15000 /dev/rwd2e
 >  /dev/rwd2e: 476934.8MB (976762544 sectors) block size 65536, fragment size 
 > 8192
 >          using 117 cylinder groups of 4076.38MB, 65222 blks, 512 inodes.
 >  
 >  This means 59904 inodes where I'd rather have more like, well, 15000.
 >  (I really wish newfs hadn't lost -c.)  Annoying but hardly fatal.
 
 The 'problem' (which ffsv2 really ought to have fixed) is that the
 allocation bitmap is constrained to fit in one fs block (64k above).
 With 64k this is 64k*8k*8 or 4G bytes per CG (less a bit for the inode map)
 so your 477G fs needs the 117 cgs.
 
        David
 
 -- 
 David Laight: david%l8s.co.uk@localhost