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Navaneeth Sen
Asked: 2010-11-26 00:26:32 +0800 CST

Where is the journal stored?

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I was reading trough the link on journaling-filesystems and i would like to know where exactly is the journal stored in my Harddisk.

Some pointers on this image shown below
alt text

Thanks,
Sen

filesystem

2 Answers

  1. There is no fixed place for the journal, each filesystem stores it in a different place.

    If you are expecting it to be a regular file, then your are mistaken, it's more like a part of the filesystem structure like the inode table. The funny point is that ext3/4 treats it exactly like a regular file. It is usually found in the inode number 8, but this is a kernel parameter that can be changed at compile time.

    If you want to get technical, this article by Carlo Wood, written in March 2008, is a great read about the ext3 structure.

    If you don't mind put journal in a place with words like partition table, inode or block and don't worry about it:

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  2. Best Answer

    The journal is stored in a separate space of the partition, you cannot access it directly. You can use sudo debugfs /dev/sda# where the # symbol is the number of your partition, and then using logdump in debugfs to print it out. The output is confusing though.

    Generally, as a regular user, you don't need to know about the journal. Using ext3/4 will be sufficient to prevent data loss (in most cases).

    This link might help: http://www.linuxforums.org/forum/red-hat-fedora-linux/121074-ext3-journal.html

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