On Samstag 02 Mai 2009, Anthony Metcalf wrote: > Jim Cunning wrote: > > On Saturday 02 May 2009 13:43:27 Volker Armin Hemmann wrote: > >> how do you do 10 with only two disks? You need four! > >> the kernel is able to autoassemble - so you don't need an initrd - me I > >> hate initrds. > > > > RAID10 = RAID1+0. It works fine with 2 disks. I was able to create it > > first with one drive missing and then add the second, which sync'ed > > without problems. > > Theoretically, for RAID 10, you need 4 disks, two raid 1's then used to > make a RAID 0 (or the other way round, I forget....) > > BUT, mdadm will use partitions instead of disks.....So you can make a > RAID 10 where each stripe takes up half the disk, and the stripes are > mirrored on each disk....Or each disk is mirrored on itself, and the two > disks stripped....Or something.... > > Won't give you the performance advantages of RAID 10 though, but will > still waste half your space.....
even worse - performance will be even more reduced because the harddisk not only have to write the own stripe but the mirrored one too. Results in more seeking. Seeking = bad. Simple Raid1 would be a lot better. And since Raid1 is 'striping' the read accesses two you have a nice little improvement there.
