On Mon, 2007-10-29 at 22:26 +0100, Simon Lundell wrote: > > > On 10/25/07, Dave Kleikamp <[EMAIL PROTECTED]> wrote: > On Thu, 2007-10-25 at 11:18 +0200, Simon Lundell wrote: > > > > > > On 10/23/07, Steve Costaras <[EMAIL PROTECTED]> wrote: > > Yes, I use the filefrag tool from Theodor > Tso' (ext2/3) which > > works on pretty much any filesystem under linux. > That defrag > > tool you mentioned would work as well (it's just > copying > > files) I don't like how it doesn't check for file > integrity > > though. > > > > Here's a fast one I through together ages ago which > works to > > some extent (no pun intended. ;) ) I never got it > to take a > > command-line argument as to which directory / mount > point to > > start on (it just runs from the current directory on > down). > > But that's easy to change (must have been > interrupted). > > Anyway do with it what you will. :) > > > > > > What is the the best way to write a file with respect to > > fragmentation? I guess that its best that the filesystem > knows the > > final size in advance, so that it can allocate it in as few > extents as > > possilbe. > > When doing a large write, jfs SHOULD at the very least > allocate a > contiguous extent large enough for the data being > written. Currently it > does not. It allocates on page at a time. So on a fragmented > file > system, the file can be quite fragmented. I have plans to > improve this, > but I haven't gotten to it yet. > > I've been experimenting with a general defragmenter like the script > posted in this thread. The basic algorithm is to rewrite the file, and > hope that the copy is less fragmented than the original. What is the > best way of copying/rewriting a file with regards to fragmentation? > Will cp do the trick or should one use something else?
Actually, I believe if you open a file with O_DIRECT, and write in large chunks, jfs will allocate blocks in groups larger than the page size, so you should get better results. I'm talking off the top of my head and haven't verified it, but it is probably worth a try. Shaggy -- David Kleikamp IBM Linux Technology Center ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ _______________________________________________ Jfs-discussion mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/jfs-discussion
