[ ... ] >> 255 data disks is the theoretical limit for GF(2⁸). But it >> is a theoretical limit of the algorithms - I don't know >> whether Linux md raid actually supports that many disks. I >> certainly doubt if it is useful. > The reason to use many disks is in case of geo-redundant RAID, > for example with iscsi. In this situation you want to have a > lot of redundance, in parities, not mirror. is that something that makes sense? If one has the extreme requirements implied by that why not use self repairing coding similarly to Parchive style storage formats, for example Typhoon or the Azure filesystem or others inspired by Parchive. Out of interest I just did a small web search and it turned up a recent survey/lecture by Frédérique Oggier on the maths of these coding systems: http://phdopen.mimuw.edu.pl/lato12/LectPoland.pdf http://sands.sce.ntu.edu.sg/CodingForNetworkedStorage/ -- 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
