On Wed, 2007-01-31 at 15:30 -0500, Jason Fisher wrote: > $ > dd if=/dev/zero of=test bs=1024k count=1000 > 1048576000 bytes (1.0 GB) copied, 168.072 s, 6.2 MB/s > > I've tested all variations between 1024 - 1024k with 1-4GB of > data--doesn't really matter--it's like hitting a wall.
My bad. Only O_DIRECT writes allocate in bigger chunks. Normal writes are still allocated a page at a time. This is something I want to address when I get the time. > You may be right on the 4095 blocksize. I checked my history and it > was a bs=10k, count=1 that resulted in 2-3 extents being used every > 10th write. But that still means 10% of the time, this jfs couldn't > find three contiguous blocks on a drive with 800GB+ available. So it's not that jfs couldn't find 3 contiguous blocks, but that it really doesn't look for them. It's allocating one block at a time, and will grow into contiguous space if it can. > The > main use was for MythTV, but I did back up a few other systems on to > it (without tarring first) at one point. If I created 300,000 smaller > files and let Myth fill the drive a few times over, I suppose I could > see how this may snowball. > > I do agree that a defrag tool designed for jfs would probably solve > this. Either way, your work on jfs is appreciated and it served me > well for some time. I'll be keeping an eye on the project in > anticipation of a proper defrag tool. I can't promise anything soon. My main focus at work is in other areas now, and my free time has been away from the computer lately. Unless someone else is willing to devote some time to this, it may be a while. > Thanks again, > Jason Fisher Thanks for your patience, Shaggy -- 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
