>> > The machine is a dual P90 (running SMP) - I get the problems even with a >> > single CPU kernel... It's running Neptune chipset (quite old) - and only >> > has 1 IDE channel. >> >> I would say that this has something to do with the DMA support, but since >> Neptune's IDE controller isn't DMA capable and PCI, that doesn't follow. >> Chances are that there's a not-quite-bad spot on your drive -- does it >> always seem to happen in the same place on the disk? > >Nope, it's more 'load' oriented than 'spot' oriented (i.e. the harder you push >them - the more of the above you get)... Both drives are brand new out the box >(for what it's worth), so I doub't they're 'bad'... DMA is disabled in the >kernel config as well, and the dmesg shows no hints of either multi-block or >DMA transfers...
New models of IBM IDE drives are fast enough to consume a significant fraction (perhaps > 100%) of PIO mode 4 bandwidth (16.6 MB/s). Don't use them without DMA. Don't use them without UltraDMA (33.3 MB/s) if you want full performance. Bruce To Unsubscribe: send mail to majord...@freebsd.org with "unsubscribe freebsd-current" in the body of the message
