mkfs oddity

[D. Hugh Redelmeier]

I've got a really big disk for MythTV (1.5T!).  Two, actually.  Mind
you, the reports of problems with these Seagate drives make me regret
buying them.  But that's not why I'm writing.

I'm creating a really big partition and I decided that since Myth
files are really big, the file system needn't have a lot of inodes.

As you can see, I asked for 100000 inodes (probably 40 times more than
I need, but a lot fewer than the default of almost 90 million).

So why did it choose to give me 174864 inodes?

(Ubuntu 8.10 + MythUbuntu packages + updates)

    $ sudo mkfs.ext3 -N 100000 /dev/sdf6
    mke2fs 1.41.3 (12-Oct-2008)
    Filesystem label=
    OS type: Linux
    Block size=4096 (log=2)
    Fragment size=4096 (log=2)
    174864 inodes, 358090850 blocks
    17904542 blocks (5.00%) reserved for the super user
    First data block=0
    Maximum filesystem blocks=4294967296
    10929 block groups
    32768 blocks per group, 32768 fragments per group
    16 inodes per group
    Superblock backups stored on blocks: 
	    32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208, 
	    4096000, 7962624, 11239424, 20480000, 23887872, 71663616, 78675968, 
	    102400000, 214990848

    Writing inode tables: done                            
    Creating journal (32768 blocks): done
    Writing superblocks and filesystem accounting information: done

    This filesystem will be automatically checked every 33 mounts or
    180 days, whichever comes first.  Use tune2fs -c or -i to override.
    $
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