On Wed, Oct 27, 2004 at 11:14:05AM -0400, Judd Tracy wrote: > I have a system that I am testing out lvm on to get a feeling about > stability and performance. Stability right now seems good, but I am a > little worried about the performance currently I am writing out a large > file ~1TB using dd if=/dev/zero of=test bs=1M and am noticing the load > seams extreamly high "5.21, 5.26, 5.17". Most of the work is being done > in dd but I also notice that kswapd0 is also working fairly heavily. Is > this to be expected with LVM or do i have things setup wrong. Write > performance seems to be around 100MB/s on an XFS filesystem. This may be a result of how load average is calculated. What is the CPU usage when doing these (see top)? On a machine with a large number of processes accessing the disk, it is quite easy for a single, I/O intensive application (such as your dd) to drive the load up. The load average is telling you that you have 5 processes blocked waiting for I/O. Without the dd, the time taken to service each is reduced, and the average number blocked at any given time is therefore lower. On our combined shell/web/email server, an I/O intensive process will result in a load of well over 10, yet responsiveness of the system is not actually that bad, and cpu usage remains low. Paul _______________________________________________ linux-lvm mailing list linux-lvm@redhat.com https://www.redhat.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
