hum, if you check docs, source, and test, you will check that md raid can have >=2 mirrors without problems, you can have 3 disks and 3 mirrors, you can have 3 disks and 2 mirrors, you can have 1 disk with 10 partitions, and each partition be a mirror of each other, the point here is, md software isn´t a hardware raid, it´s very near but have more features, i don´t know if we should change md to allow it be compatible with a 'industrial standard' since we have more feature than standard, you must check what you want and use it maybe some article at wiki, standard X, layout Y, level W = md raid level A layout B devices C mirrors D spares E ..... i think this is welcome to linux wiki page 2011/5/9 Keld Jørn Simonsen <keld@xxxxxxxxxx>: > On Mon, May 09, 2011 at 01:22:42PM +0800, Emmanuel Noobadmin wrote: >> On 5/6/11, Keld Jørn Simonsen <keld@xxxxxxxxxx> wrote: >> > Hi List >> > >> > based on the recent discussion, that showed lacking knowledge >> > on Linux MD RAID10 features, I have some thoughts: >> > >> > It is really hard to disseminate information on "new" features >> > in MD RAID. RAID10 has been in the kernel since 2.6.9 - from 2004. >> > I have tried to give info on RAID10 at a number of web pages, >> > and still many people, even on our linux-raid list are not aware >> > of it. >> > >> > Also many people are confused about Linux MD raid10 and RAID1+0. >> > >> > So I think we shopuld rather name things in another way. >> > >> > I would like linux MD raid10 functionality to be part of the Linux MD >> > RAID1 module, and be called raid1. This is in accordance with the >> > use of the RAID1 term as standadized by SNIA. In fact the RAID10-offset >> > layout is an implementation of a SNIA RAID specification. The RAID10-near >> > layout is an implementation of a simple RAID layout. And the RAID10-far >> > layout is just another layout far a mirrored RAID. So all these types >> > could just be defined as different RAID1 layouts. >> >> Giving my noob's 2 cents worth although I haven't followed the >> original discussion. As a noob, I think doing this will just confuse >> us more. >> >> There are plenty of existing materials around for those of us who try >> to figure things out by googling. As it is, our (or maybe just me) >> understanding is Linux RAID 1 is just like every other raid 1: simple >> and straightforward, 2 drives mirroring each other. >> >> This is is also usually the level that most of us start with. If the >> instructions are short, easy to understand and simple to implement, we >> usually gain confidence in using it and exploring mdraid further. >> >> Most of us noobs are also aware that RAID 10 is more complicated and >> there are two versions, i.e. 1+0 and 0+1. So psychologically, I had no >> problems accepting that once I looked into it, there were much more >> complex stuff and all these possible layouts: mdraid is cool! >> >> Now, if RAID 10 was renamed to RAID 1, with the corresponding change >> in documentation, what's going to happen for us noobs is this: "Omg, >> why are there so many different versions and options just for raid 1?" >> and importantly "Why is this manual/wiki different from the tons of >> other pages about using mdraid 1?" For some, this would mean mdraid is >> too difficult even for raid 1, mdraid is not cool! :) >> >> So newbies will get more confused/frustrated as a result. >> >> Personally, I had to spend some time figuring out (I'm noob and I'm >> not very smart) the different layouts from the examples on wiki. This >> is because there wasn't enough examples, at least to me, to clearly >> show what's the difference if more/less disks were used. So for me, >> and other noobs, it would probably help if the wiki had more examples >> of each layout, maybe graphics to show the difference since it's >> probably easier to see things if they were colour coded blocks rather >> than stuff like A1 a1 A2 a2. >> >> This and perhaps more elaboration on the difference between mdraid 10 >> and normal raid 10 would probably be better to clear up confusion >> than renaming something we might have some familiarity with, into >> something we also already have familiarity, resulting in something >> that contradicts existing familiarity. > > I see your point. Given Neil's input I think we should rateher call it > raid1e. > > Best regards > keld > -- > 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 > -- Roberto Spadim Spadim Technology / SPAEmpresarial -- 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
