Devices should only show up as
/dev/hd* when your kernel is using the ancient IDE subsystem instead of the modern
libata interface to talk with your hard disk controller. With
libata, even old IDE devices should show up as
/dev/sd* because libata exposes all devices through the SCSI subsystem.
I'm having problems related to high iowait. Does this have something related?
When you're using the IDE subsystem, you're probably forcing your SATA controller into IDE emulation which could have a negative impact on the performance, yes.
On motherboard setup the SATA mode are Enhanced.
Hmm... does your BIOS have an AHCI option? Enabling AHCI would be the best option because AHCI is the most modern and the fastest interface, but the mainboard seems to be rather old... it is possible that it doesn't support AHCI. Upgrading to a newer mainboard could solve your issues.
Please provice the output of the following commands, so we can figure out why your server is using the ancient IDE subsystem: