UFS2 snapshots on large filesystems

[Oliver Fromme]

Oliver Fromme <olli at lurza.secnetix.de> wrote:
 > user <user at dhp.com> wrote:
 > > On Sun, 6 Nov 2005, Eric Anderson wrote:
 > > > [fsck on large file systems taking a long time]
 > > 
 > > Can you elaborate ?  Namely, how long on the 2GB filesystems ?
 > 
 > It depends very much on the file system parameters.  In
 > particular, it's well worth to lower the inode density
 > (i.e. increase the -i number argument to newfs) if you
 > can afford it, i.e. if you expect to have fewer large
 > files on the file system (such as multimedia files).

I just accidentally pulled the wrong power cord ...
So now I can give you first-hand numbers.  :-}

This is a 250 Gbyte data disk that has been newfs'ed
with -i 65536, so I get about 4 million inodes:

      Filesystem     iused      ifree  %iused
      /dev/ad0s1f  179,049  3,576,789     5%

So I still have 95% of free inodes, even though the
filesystem is fairly good filled:

      Filesystem     1K-blocks         Used       Avail  Capacity
      /dev/ad0s1f  237,652,238  188,173,074  30,466,986     86%

fsck(8) took about 2 minutes, which is acceptable, I
think.  Note that I always disable background fsck
(for me personally, it has more disadvantages than
advantages).

This is what fsck(8) reported when the machin came
back up:

      /dev/ad0s1f: 179049 files, 94086537 used, 24739582 free
      (26782 frags, 3089100 blocks, 0.0% fragmentation)

Best regards
   Oliver

-- 
Oliver Fromme,  secnetix GmbH & Co. KG, Marktplatz 29, 85567 Grafing
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"Python tricks" is a tough one, cuz the language is so clean. E.g.,
C makes an art of confusing pointers with arrays and strings, which
leads to lotsa neat pointer tricks; APL mistakes everything for an
array, leading to neat one-liners; and Perl confuses everything
period, making each line a joyous adventure <wink>.
        -- Tim Peters