On Fri, May 06, 2011 at 10:22:33AM +0100, Jonathan Tripathy wrote: > > On 06/05/2011 10:03, Keld Jørn Simonsen wrote: > >On Fri, May 06, 2011 at 01:31:59PM +0600, Roman Mamedov wrote: > > > >>On Fri, 6 May 2011 09:17:52 +0200 > >>Keld Jørn Simonsen<keld@xxxxxxxxxx> wrote: > >> > >> > >>>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. > >>> > >>RAID1 is RAID1, RAID10 is RAID10. > >>RAID1 on 4 drives is very different from RAID10 on 4 drives. > >>Don't add confusion by trying to rename RAID10 to RAID1. > >> > >How are they different? > >Say what is the difference between a Linux MD RAID1 with 4 disks, and > >the default Linux MD RAID10 with 4 disks? (in the near layout)? > > > > > RAID1 is traditionally a mirror only setup (ok, some RAID > implementations may do some load-balancing of some sort). So a RAID1 > with 4 disks is one data set copied onto 4 disks. Bandwidth is roughly > the same as a single disk (ignoring any load balancing). > RAID10 is mirror and stripe. A RAID10 with 4 disks is similar to a 2 > disk RAID0 (double bandwidth with data split in half across both disks), > but with each disk having a mirror (which brings the total up to 4 drives). > > Additionally, a RAID1 disk (at least using MD) can be accessed just like > a normal disk (good for recovery etc.) however a single disk out of a > RAID10 array is next to useless. I think you are demonstrating some of my points about general knowledge quite nicely. Don't worry, you are not alone. 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
