On Thursday 22 April 2010 08:02:08 Phill Coxon wrote: > Hi, > > I'm currently running KUbuntu 8.04.4. > > I'll be upgrading to KUbuntu 10.04 LTS in a few days so it's possible > that the upgrade will fix this problem but I'll ask anyway. > > I've been having this ongoing problem with certain tasks doing massive > disk I/O that results in the desktop becoming completely unresponsive. > > Guilty tasks include updatedb, Amarok rebuilding it's collection data > and VMWare starting up or shutting down - basically any task that is > doing a very large amount of reading from the main drive. > > When this is happening my desktop can become unusable for 30-90 seconds. > Opening a new shell can take 30-45 seconds to appear, applications will > pretty much freeze until the disk calms down. > > Is there any way to place limits so that a particular task can't hog all > of the disk I/O at the expense of everything else? > > The drive is a Western Digital 320Gb 16Mb SATA II, ext3 file system. > > Thanks!
My two cents: I was building a new system for home out of a few bits I had lying around. For this system I purchased a Western Digital SATA hard drive, WDC WD8088AADS. I installed $DISTRO, and I experienced the same problem you are describing. I noticed when running "top" that the "%wa" figure would go sky-high when the system was bound up. Googling "top %wa" led me to a definition for "wa" which was "waiting for I/O" Further searching indicated that this problem can occur when using usb flash drives, and that a handling is having a better scheduler in the kernel, or using the latest kernel, 2.6.33, which has a better scheduler. So I compiled three kernels with different scheduler settings, and tried these. This didn't make any difference. Then I upgraded to 2.6.33, and this didn't make any difference. Further experimenting with the system showed that the same O/S, running from an IDE drive, did not have this problem. So I thought perhaps the problem could be with the SATA chipset on the motherboard. I purchased a SATA to PATA bridge, and plugged the SATA drive into an IDE port. I got the same problem. The SATA to PATA bridge is entirely hardware, and the O/S thinks it is talking to a PATA drive. Summary: The Western Digital drive, plugged into a SATA port, has I/O problems. A PATA drive plugged into a PATA port, does not have I/O problems. The Western Digital drive, plugged into a PATA port through a bridge which the O/S can't see and thus uses PATA drivers for, has I/O problems. Conclusion: I think the problem is with the hard drive. Unfortunately I don't have another SATA drive I can use to confirm that a different drive by a different manufacturer, may work ok on the SATA bus. Cheers, Wayne
