my IDE channels on ICH5 are obviously not independent. In /proc/ide they are pointing to each other as "mates". How do I make them operate independently?
I have a Asus P4C800-E Deluxe, which has onboard ICH5 (i875 chipset) and an onboard Promise controller. When I was using this combo with SATA drives, everything was fine and all drive independent, RAID-0 performance was about the sum of the drives.
Now I dropped the SATA stuff and got parallel ATA drives (and stuffed in another P-ATA promise PCI controller) and now obviously the ICH5 channels are not independent anymore. The performance in RAID-0 is very clear that any combination of one drive on ICH5 and one drive on the promise is full speed, but two drives on the ICH5 is dog slow.
- drive alone:
4294967296 B 4.0 GB 68.50 s 62698102 B/s 59.79 MB/s
- RAID0 one drive on ICH5 and one on Promise:
8589934592 B 8.0 GB 75.84 s 113269421 B/s 108.02 MB/s
- RAID0 with two drives on ICH5:
8589934592 B 8.0 GB 135.02 s 63620366 B/s 60.67 MB/s
- the drives are on different channels on the ICH5
- in SATA mode everything worked as expected, only P-ATA seems to marry them
I run Fedora Core 2 2.6.8-1.521custom. I didn't change the configuration, it is only marked "custom" because I recompiled and installed it to make software like vmware happy that the source matches the running kernel.
1) I looked at the kernel source for IDE and didn't see anything resembling a knob to turn this on or off. Any ideas?
2) is it possible that one of Fedora's patches caused this? Maybe this is one of the Redhat/Fedora safety belts like not turning on DMA in the past? I diffed the IDE driver to the Linus driver and couldn't spot anything that could have caused this.
Here's dmesg for IDE. The full dmesg is on
EDIT: the forum didn't let me include the dmesg cut'n'paste, complaining about too many images. Yeah, right