Peter Farrow <peter at farrows.org> wrote: > [root@ ~]# hdparm -t /dev/hdb > /dev/hdb: > Timing buffered disk reads: 62 MB in 3.07 seconds = > 20.17 MB/sec > [root@ ~]# hdparm -t /dev/hda > /dev/hda: > Timing buffered disk reads: 62 MB in 3.02 seconds = > 20.51 MB/sec Ouch! They are on the same channel! Furthermore, you're only getting the cache speed. Try "-Tt" instead. And try running those 2 commands simultaneously! You're going to see more than a 50% drop (more like an 80%!). > UDMA modes: udma0 udma1 *udma2 udma3 udma4 udma5 > UDMA modes: udma0 udma1 *udma2 udma3 udma4 udma5 Ultra DMA mode 2 (33MHz) is a good sign. > I'm running software RAID and they are both on one IDE > controller, but this is because the installer detects > the drive geometry differently for each if they are on > separate controller, If it's Award BIOS, then set the geometry to "LBA" in the BIOS. Furthermore, _regardless_ of what the BIOS says, once you partition with LBA, if you move it to another controller, the partition table will _still_ be LBA when Linux loads the partitions. > which would be the best option, but as I am doing mirroring I > want the geometry the same. The geometry is _already_ the same once the partition table has been created. Linux _ignores_ the BIOS' geometry if it was partitioned differently. > Furthermore no amount of changing in the BIOS affects the > detected geometry by Anaconda. I've seen this quite a lot on > Compaqs. Oh, a Compaq. Yeah, broken BIOS. But _regardless_, you've already got the correct geometry. You can now move channels, Linux will read the partition table and use its geometry -- not what the BIOS says. ATA DMA was _never_ designed for master/slave, that's an old EIDE PIO configuration. Drives only allow it to be compatible, but it's not recommended at all. -- Bryan J. Smith | Sent from Yahoo Mail mailto:b.j.smith at ieee.org | (please excuse any http://thebs413.blogspot.com/ | missing headers)