There is an interesting analysis of filesystem pathname distributions available in a master's thesis at: http://www.pdl.cmu.edu/PDL-FTP/HECStorage/Yifan_Final.pdf This shows (at least for the filesystems analyzed) that median directory sizes continue to be quite small. Looking at figure 10, 60-90% of all directories have 8 or fewer entries in them, and in many cases 50% of directories have only 1 or 2 entries. It would be useful for you to run the fsstats tool (available from http://www.pdsi-scidac.org/fsstats/) against some filesystems that you have access to (e.g. typical distro desktop and home directory, file servers, etc) and compute what fraction of the files and directories could be stored inside the inode. Similarly, and perhaps more importantly, for any filesystems you have using the bigalloc feature, compare the actual size of files and directories (only the filename + 10 bytes) to see how many you could fit into an inode of a given size. A default 256-byte inode has about 100 bytes of space, a 512-byte inode has about 350 bytes of space, etc). It would be useful to see if there is a clear win for having larger inodes to hold small files/directories in bigalloc filesystems, or whether this would waste more space in total than is wasted by allocating a full bigalloc block for each inode. Cheers, Andreas -- Andreas Dilger Whamcloud, Inc. Principal Lustre Engineer http://www.whamcloud.com/ -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
