no matter what raid1 or raid10 system we use raid1 is mirror! let´s think that raid0 = more than one disk (not a single disk)... if a hard disk inside a mirror (raid1) fail (it can be a raid0 or a single disk) the mirror is failed for example: there´s no 25% survival for 2 mirrors with 4 disks! probability, here, is mirror based, not disk based! it´s not a question about linux implementation is a question for generic raid1 (mirror) system (1 failed 2 mirrors = 1 mirror failed but 1 mirror working) you only can have 25% 'survival' if you can use 4 disks, or multiples of 4, for raid1 if your raid0 is broken you don´t have a raid0! you have a broken raid = broken mirror (for raid1)! should i write it again? for raid10 (raid1+0) with 4 disks you can only lost 1 disk! 1 disk lost = 1 raid0 lost = 1 mirror lost! should i write it again? 2011/1/31 Keld Jørn Simonsen <keld@xxxxxxxxxx>: > On Mon, Jan 31, 2011 at 02:17:37PM -0600, Stan Hoeppner wrote: >> Keld Jørn Simonsen put forth on 1/31/2011 1:28 PM: >> > Top-posting... >> > >> > How is the raid0+1 problem of only 33 % survival for 2 disk with RAID10? >> > >> > I know for RAID10,F2 the implementation in Linux MD is bad. >> > It is only 33 % survival, while it with a probably minor fix could be 66%. >> > >> > But how with RAID10,n2 and RAID10,o2? >> >> I don't care what Neil or anyone says, these "layouts" are _NOT_ RAID 10. If >> you want to discuss RAID 10, please leave these non-standard Frankenstein >> "layouts" out of the discussion. Including them only muddies things unnecessarily. > > Please keep terminology clean, and non-ambigeous. > Please refer to the old term RAID10 as RAID1+0, which is also the > original and more precise term for that concept of multilevel RAID. > > RAID10 on this list refers to the RAID10 modules of the Linux kernel. > > I can concurr that this may be a somewhat misleading term, as it is > easily confused with the popular understanding of RAID10, meaning > RAID1+0. And I see Linux RAID10 as a family of RAID1 layouts. > Indeed RAID10,n2 is almost the same as normal RAID1, and RAID10,o2 > is an implementation of a specific layout of the RAID1 standard. > RAID10,f2 could easily also be seen as a specific RAID1 layout. > > But that is the naming of terms that we have to deal with on this Linux > kernel list for the RAID modules. > > 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
