[Date Prev][Date Next] [Thread Prev][Thread Next] [Date Index] [Thread Index]

Re: mke2fs & capacity (where did it go!?)



On Mon, 15 Dec 1997, matthew tebbens wrote:

> On Mon, 15 Dec 1997, David Wright wrote:
> 
> > On Sun, 14 Dec 1997, matthew tebbens wrote:
> > 
> > > (victor)[root:~#] mke2fs -c -v /dev/sda1
> > > mke2fs 1.10, 24-Apr-97 for EXT2 FS 0.5b, 95/08/09
> > > Linux ext2 filesystem format
> > > Filesystem label=
> > > 1101824 inodes, 4401778 blocks
> > > 220088 blocks (5.00%) reserved for the super user
> > > First data block=1
> > > Block size=1024 (log=0)
> > > Fragment size=1024 (log=0)
> > > 538 block groups
> > > 8192 blocks per group, 8192 fragments per group
> > > 2048 inodes per group
> > > Superblock backups stored on blocks:
[...]
> > > What am I missing here ??
> > 
> > 4,033,188 + 220,088 + 13 = 4,253,289 so that's all right then.
> > But that's not what's at issue.
> > What's relevant is the 4,401,778 blocks which becomes 4,507,420,672 bytes.
> > That looks better. But even that is only looking at the first partition
> > (sda1, sdb1 etc.)
> 
> But I don't have 4,401,778 blocks, I only have a total of 4,253,289 blocks
> which becomes aprox 4,355,367,000 bytes.
> 
> How does it get from 4,401,778 blocks to 4,253,289 blocks ?
> Somewhere along the line I lost about 250,000 blocks... ??

The partition has 4,401,778 blocks in total. There are 4,253,289 blocks 
available for your data. Somewhere, the filesystem has to describe where 
all that data is.

Your filesystem has 1,101,824 inodes and, taking a quick look at 
/usr/src/linux/include/linux/ext2_fs_i.h which describes inodes in 
memory, there seem to be about 112 bytes in an inode. That adds up to 
about half your "missing" space. But there's more to describing the 
filesystem than just the inodes, and ext2 is optimised for performance, 
which must mean using more space for chains of descriptors etc.. Perhaps you 
should read a book on linux internals to find out what you're missing. 
(Sorry for the pun.)

--
David Wright, Open University, Earth Science Department, Milton Keynes MK7 6AA
U.K.  email: d.wright@open.ac.uk  tel: +44 1908 653 739  fax: +44 1908 655 151


--
TO UNSUBSCRIBE FROM THIS MAILING LIST: e-mail the word "unsubscribe" to
debian-user-request@lists.debian.org . 
Trouble?  e-mail to templin@bucknell.edu .


Reply to: