Historically it was sd[a-z][a-z][0-14] The number of devices is determined by (number of major numbers) x (number of minor numbers) รท (number of partitions). I think there's 12 bits for major number and 20 bits for minor numbers, and a max of 15 partitions. Newer kernels added a means to do dynamic device number allocation, so i don't know what the actual limits are.
I don't know what the kernel built-in default naming scheme for the higher drive numbers is currently. Nowadays that's often left up to udev rules--some distros override the kernel defaults to provide a persistent naming convention. As for mdadm, that depends on the superblock format chosen. v 0.90 limits it to 28 components. Version 1.0 supports at least 384, to a theoretical max of 64k component devices. Also, the superblock version determines limits on both maximum component size and total volume size of the combined array. /* PLUG: http://plug.org, #utah on irc.freenode.net Unsubscribe: http://plug.org/mailman/options/plug Don't fear the penguin. */
