At Thu, 19 Aug 2010 09:54:32 -0500 CentOS mailing list centos@centos.org wrote:
With the default settings in my Supermicro motherboard CentOS calls my SATA drive /dev/hda. If in bios setup I change 'Native Mode Operation' from auto to 'Serial ATA' it boots up calling the drive /dev/sda. I keep thinking its likely better under /dev/sda not? Any problem switching it to that after install?
So I guess another question here. Is it better to my SATA interface in Serial ATA mode or AUTO in BIOS? The motherboard calls it sda when in serial ata mode but hda when in auto mode. Will there be a performance difference?
Yes. SATA is going to be faster. Note: your 'motherboard' is not calling it sda or hda. What your motherboard is doing is either *native* Serial ATA mode or *emulated* Parallel ATA (aka IDE) mode (also known as 'legacy' mode). The linux *kernel* then either sees IDE disk(s) (*emulated* Parallel ATA mode) or native Serial ATA disks, and loads a Serial ATA driver, which uses the SCSI disk abstraction layer (sd). The *native* Serial ATA mode is faster and more feature-rich, such as including things like hot-swapping, should you install a SATA hot-swap bay. This is not possible with IDE disks and the IDE disk driver does not really support it. Also, motherboards with more than 4 SATA ports will only make 4 available when in 'IDE' mode. If there are more than 4 SATA ports on your motherboard, you need to be in native SATA mode to use all of them. This includes any E-SATA ports as well.
The only problems with switching after install is:
1) you need to be sure the initrd has the (proper) SATA kernel module(s) in it. If necessary, you'll have to use mkinitrd to re-create the initrd file to include the proper driver modules.
2) /etc/fstab needs to be fixed, either to use LABEL= (rather than /dev/hdaN) and your file systems (including swap) need to have file sytem labels. (LVM volumes won't be a problem.)
Matt _______________________________________________ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos