On 02/18/2013 11:06 PM, Nico Kadel-Garcia wrote:
IDE drives used to be listed as "/dev/ide0, /dev/ide1, etc." in deterministic fashion, but that got tossed out when they started labeling all drives as /dev/sda to gove access to special SCSI compatible commands.....
Aka 'the libata takeover'. It does make all drives pretty much consistent. There are still a few older controllers that behave better with the old IDE drivers than with libata; old Intel P4 chipsets in particular.
The result is that it's guesswork. This is why our favorite upstream vendor tried for a while to use "LABEL=" settings to identify particular partitions, instead of trying to deduce what would be detected where.
This is partially due in EL6 to the use of dracut and it's new initrd udev-ish system. I have one RHEL 6 box that is hooked to a pretty good-sized array on fibre-channel; it's fully HA, so there are four paths to any given LUN. My boot device, a 3Ware 9500-series SATA RAID card, ends up with a device name for it's first logical disk anywhere between /dev/sda and /dev/sdah; it's been /dev/sdu, /dev/sds, /dev/sdt, /dev/sdz, /dev/sdab, and pretty much everything in between, and it will vary from one boot to the next; it's at /dev/sdad right now. But I have the 3ware card, an on-motherboard U320 SCSI controller, a four-port Silicon Image SATA card, and a dual-port FC card hooked to the SAN.
