On Sat, Jul 12, 2008 at 08:44:48PM +1000, Neil Brown wrote: > On Saturday July 12, keld@xxxxxxxx wrote: > > I took the information here and made something for the wiki. > > Comments welcome. /keld > > Thanks for doing that. I'm not motivated to work on the wiki myself, > but I'm more than happy for anyone to take any secrets I divulge in > emails and publish them there. > > > > > = recovery and resync = > > > > The following is a recollection of what Neil Brown and others have > > written > > on the linux-raid mailing list. > > > > "resync" and "recovery" are handled very differently in raid10. > > "check" and "repair" are special cases of "resync". > > > > == recovery == > > > > The purpose of the recovery process is to fill a new disk with the > > relevant > > information from a running array. > > > > The assumption is that all data do the new disk needs to be written. > > > > "recovery" walks addresses from the start to the end of the component > > drives. > ... > > > > == resync == > ... > > > > "resync" walks the addresses from the start to end of the array. > > It's probably worth noting that this difference between recovery and > resync in specific to raid10. > > recovery always follows the address space of component drives. > > resync: > on raid10, follows the address space of the array > on raid4/5/6, follows the address space of component drives. > on raid1, the two address spaces are the same. > > Another way to say it is that raid10-resync follows the address space > of the array, everything else follows the component drives. OK, I added that info: For raid10 "resync" walks the addresses from the start to end of the array. (For all other raid types "resync" follows the component drives). I also added that for recovery, it is assumed that the running drives are in sync. Is that true? I wrote it as: The assumption is that all data on the new disk needs to be written, and that the other data on the running array is correct. I also wrote this to indicate the difference between a component drive walk, and a full array walk: "recovery" walks addresses from the start to the end of the component drives. Thus only data for the specific component drive is adressed. -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
