> But having a WWN generator in the kernel, although not terribly > difficult to write, makes it possible to create an inconsistent > storage domain. It is that possibility which troubles me, > due to the intention of SAS WWNs. But one should make sure that you *do* create a consistent storage domain. If you can seed the system with a couple dozen free WWNs for use when/if needed, why not? People are content to believe that UUID generation is sufficiently unique, and for the bit space it occupies that's probably a reasonable clain. But you can't jam that into the smaller bit space WWNs. For smaller bit spaces like 64 bit WWNs, you cannot, as you correctly point out, generate reliably unique numbers all by youself. The closest you could probably come is using a type 5 WWN with a known single OUI and then use "seconds since January 1 2007" as a serial number in the 36 bit VID space that gives you about 8 years before it wraps- the likely collision rate here would be pretty low. A much better choice is to get real stamped serial number WWNs. I also hold with some of the other folks on this discussion that some of this is policy that the admin should be allowed to choose. After they've segmented the company's main fabric by choosing unwisely and forgetting to practice safe zoning we'll choose to buy them a drink or two. - To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
