I had similar problems with a MSI P45 board (ICH10) and mdadm raid6 rebuild speed bios default settings : 1 MB/s enabling IDE busmaster: 22 MB/s switching from IDE to AHCI: 33 Mb/s Roelof Ken Teh wrote: > I solved the problem and thought I'd pass it along. The BIOS also has > a SATA AHCI setting which was disabled. After I enabled it, the disks > are now recognized as /dev/sd? and I'm getting more reasonable disk > speeds. I also do not get the ata_piix message about "no available > legacy ports". > > Ken > > Ken Teh wrote: >> I just installed SL5.3 on a Supermicro PDSBE motherboard and its disk >> i/o is painfully slow; about 3MB/s. The system has SATA drives but >> the kernel sees them as /dev/hdx devices. There is also a ata_piix >> message at the beginning of bootup that says "no available legacy >> port". I'm guessing the failure to recognize the SATA drives as >> /dev/sdx and the slow disk i/o are related to this cryptic message. >> >> I ran a Fedora 11 live CD on the system and it can do disk i/o easily >> 20-30 times faster which is closer to what I expect. 100MB/s or >> more. I'm pretty sure the problem is kernel related. >> >> I tried switching the SATA mode in the BIOS to compability instead of >> enhanced. It didn't make any difference. I wasn't expecting any. >> The compatibility vs native stuff, I thought, was something that was >> done when SATA support for spotty. The SATA controller is an Intel >> ICH8 which I figure should be well supported. >> >> I also looked at the dumps of hdparm both under SL53 and Fedora 11. >> The features enabled are the same for both. There are additional >> features listed under Fedora 11, all SCT (SMART Command Transport) >> related. There is also a whole bunch of dma modes displayed in both >> hdparm -t dumps. On SL53 there is a * next to udma5 while it's next >> to udma6 under Fedora. I'm not sure what this means. >> >> Any ideas on how to proceed? Build a custom kernel? Which I am >> reluctant to do since I rely on SL for updates. >> >> Ken