On Thu, February 12, 2009 8:46 pm, Keld Jørn Simonsen wrote: > On Thu, Feb 12, 2009 at 09:13:17AM +0000, Steve Fairbairn wrote: >> Keld Jørn Simonsen wrote: >> > >> >I would rather have functionality to convert raid10 to raid5. >> >raid1 should be depreciated, as raid10,n2 for all purposes is the same >> >but better implementation and performance, and raid10,f2 and raid10,o2 >> >are even better. Nobody should use raid1 anymore. >> > >> Complete ignorance of raid10 here, but is raid10,<anything> bootable, >> like raid1 is? I use raid1 on my root and boot partitions. > > AFAIK, raid10,n2 in default mode (superblock etc) is bootable, as it > looks like two copies of a normal FS. I think this was even reported > on this list at some time. > > You are not the only one that does not know much about raid10. I think > most Linux administrators don't. And other system adminstrators most > likely don't either. > > Maybe we should rename raid10 to raid1? > > Raid10 should just be an enhanced raid1. And I understand from Neil that > raid10,o2 is mostly done because it is a standard raid1 layout. So it is > strange that it is not available with raid1 in Linux. And I also think > that the raid10,f2 layout is available from some HW raid controllers, as > their implementation of raid1. So all what is in raid10 is other places > considered raid1 stuff. > The 'offset' layout came about to be able to support a DDF format which is called: 4.2.18 Integrated Offset Stripe Mirroring (PRL=11, RLQ=01) (4.2.18 is the section of the document PRL is Primary Raid Level RLQ is Rail Level Qualifier ) There is also 4.2.17 Integrated Adjacent Stripe Mirroring (PRL= 11, RLQ=00) which is essentially the same as our n2 layout. You should see their 4.3.4 Spanned Secondary RAID Level (SRL=03) Though. That would be really .. interesting to implement. You can down load the ddf spec at http://www.snia.org/tech_activities/standards/curr_standards/ddf/ NeilBrown -- 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
