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kumarat9pm · #1 (**permalink**) 16th November 2009, 08:42 AM

Hi all,

One of my friend asked me these following questions which i cant not answer any of them.. I think here some people can answer to these

1) when we tune from ext2 to ext3 we see a hidden file .journal but not the partitions we format with. why?
2)I read that when the file system gets mounted journal is mainted in kernel.is that rite?
3)when we do dumpe2fs of any partitions we see journal size = some size in Kilo bytes ,and the journal has a inode number assigned,so now this is file .Where is this file and how the journal size is calculated?

here is one document i refereed but no use for me

http://www.redhat.com/support/wpaper.../ext3/ext3.pdf

Or atleast refer some forums where i can get answers for this.

nixcraft · #2 (**permalink**) 16th November 2009, 11:45 AM

Quote:

1) when we tune from ext2 to ext3 we see a hidden file .journal but not the partitions we format with. why?

If you create the journal on a mounted filesystem you will see a .journal file. If you run tune2fs -j on an unmounted partition an unvisible journal file will be created.

Quote:

2)I read that when the file system gets mounted journal is mainted in kernel.is that rite?

ext3 is part of kernel, so yes Linux kernel manage ext3 via file system driver.

Quote:

3)when we do dumpe2fs of any partitions we see journal size = some size in Kilo bytes ,and the journal has a inode number assigned,so now this is file .Where is this file and how the journal size is calculated?

No inode and journal size not same. They can very. Here is output from my desktop:

Code:

dumpe2fs /dev/sdb2 | grep size

Output:

Code:

dumpe2fs 1.41.9 (22-Aug-2009)
Filesystem features:      has_journal ext_attr resize_inode dir_index filetype needs_recovery sparse_super large_file
Block size:               4096
Fragment size:            4096
Inode size:              256
Required extra isize:     28
Desired extra isize:      28
Journal size:             128M

The journal is stored inside the filesystem (see #1 answer). The size is calculated automatically from the size of the filesystem. However, you can set journal size whiel creating file systems. The size of the journal must be at least 1024 filesystem blocks (4MB if using 4k blocks) and may be no more than 102,400 filesystem blocks. For example, create 512M journal size:

Code:

 mke2fs -J size=512 /dev/sdXY

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Having queries regarding ext2 and ext3

Having queries regarding ext2 and ext3

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