On Wed, 2007-01-31 at 12:28 -0500, Jason Fisher wrote: > It's hard to say. Basically, I manually recopied files with over > 10,000 extents until I got one with 100-200 extents, and then deleted > the originals. Rinse-repeat over most of the drive. Files with tens > of thousands of extents that I didn't really need, I simply deleted. > Oddly, I had a few directories scattered about with good write speeds, > up to a certain point (i.e., 4-10gb) -- but I could never get the root > of the filesystem above 6 MB/sec or so. > > After getting the drive down to 40% usage, write speed was still just > as slow.. and this is where my problem with jfs lies. That 60% space > available should allow for contiguous space large enough that a small > (1-4MB) file should take very few extents in any case. i.e., jfs > should be smart enough to place a file where it fits well.
How are you writing the files? A large write size should help. When writing a file a bit at a time, jfs doesn't know how large the file is going to grow, so it's only going to find space to satisfy the size of the write. > In my > experience on this particular filesystem, using dd to write a single > 4095 byte file would take *three* extents every 10th write. That can't be right. An extent can't be smaller than 4096 bytes. > This is > on a filesystem with 4096 byte blocks (correct me if I'm wrong), mind > you. Something very drastic would have surely had to occur to get jfs > to respond this way. > > A new development is that it looks like this situation wasn't limited > to my 1.7tb partition. It's also affecting my /usr and /home > partitions. This means that I could probably come up with a partition > image (dd) that is of reasonable size to compress and transfer > (~1-2GB) if someone would like me to save a copy for inspection. I'm convinced that a defrag tool would be a big help. Unfortunately, I don't have the spare time to work on it now. > The jfsCommit process seems to be the doing the blocking. > > Jason -- David Kleikamp IBM Linux Technology Center ------------------------------------------------------------------------- Using Tomcat but need to do more? Need to support web services, security? Get stuff done quickly with pre-integrated technology to make your job easier. Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 _______________________________________________ Jfs-discussion mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/jfs-discussion
