Please be patient with my ignorance if what I am asking is meaningless in any way. I am not too technically knowledgeable about filesystem internals but I am willing to learn. (I thought of posting to linux-ext4 but did not want to intrude within the technical threads with my layman thread.) From Wikipedia > ReiserFS article > Design section: [quote]ext2 and other Berkeley FFS-like filesystems simply use a fixed formula for computing inode locations, hence limiting the number of files they may contain. Most such filesystems also store directories as simple lists of entries, which makes directory lookups and updates linear time operations and degrades performance on very large directories. The single B+ tree design in ReiserFS avoids both of these problems due to better scalability properties.[/quote] So will ext4 avoid both of these problems just like ReiserFS? Does it use a B+ tree? Or this "dancing B* tree" that Reiser4 is supposed to have? Also: I found that a newly created ext3 partition uses 128 MB whereas a new reiser3 partition uses only 32 MB. I assume that the 128 MB is the space taken for the pre-allocated inodes or such. And I now come to know that others have this problem much more serious on bigger filesystems - [see comment 2 at http://linux.wordpress.com/2006/09/27/suse-102-ditching-reiserfs-as-it-default-fs/]. If ext4 uses a B+ (or B*?) tree like ReiserFS then this space can be reduced, right? Thanks. Shriramana Sharma. P.S: Are there any recommended tutorials for learning filesystem basics? P.P.S: I just put this post here because I want to convert from reiserfs of uncertain future to ext4.
On Sun, 31 Dec 2006, Shriramana Sharma wrote:> So will ext4 avoid both of these problems just like ReiserFS? Does it > use a B+ tree? Or this "dancing B* tree" that Reiser4 is supposed to have?I cannot comment on stability/performance of ext4, but here are the specs: http://www.bullopensource.org/ext4/> Also: I found that a newly created ext3 partition uses 128 MB whereas a > new reiser3 partition uses only 32 MB.are you talking about ext3 or ext4? I haven't tested ext4 yet but for ext3 it looks like this: $ df -h /mnt/test0 /mnt/test1 Filesystem Size Used Avail Use% Mounted on /tmp/reiser3.img 33M 33M 944K 98% /mnt/test0 /tmp/ext3.img 15M 1.6M 13M 11% /mnt/test1 (reiser3 needs at least a 32MB image file/device)> P.S: Are there any recommended tutorials for learning filesystem basics?Hm, I'm no filesystem guru but I suggest reading the specs and the source should help a lot... my 2 cents, Christian. -- BOFH excuse #127: Sticky bits on disk.