On Friday June 21, jeffm@boxybutgood.com wrote: > > I'm looking at the kernel/user interface md_u.h and trying to figure out > how to start a linear raid, not persistant, no superblock, from my little > test program. You might find reading Build.c from http://www.cse.unsw.edu.au/~neilb/source/mdadm/mdadm-1.0.0.tgz helpful. > > My current plan of attack is to do 3 steps... > > #1. do ioctl SET_ARRAY_INFO. Which fields of mdu_array_info_t should I > fill out before passing it into ioctl? Any that make sense. level, size=0, nr_disk==raid_disks md_minor not_persistent, state=0 active_disks=working_disks=raid_disks spare_disks=failed_disks=0. chunk_size > > #2. Add disks with ADD_NEW_DISK... one mdu_disk_info_t per disk for > nr_disks (or raid_disks??) in mdu_array_info_t. Yes > > #3. RUN_ARRAY or START_ARRAY ioctl. I can't figure out which to use. It > seems that RUN_ARRAY requires a mdu_param_t arg. RUN_ARRAY. Parameter is ignored. > > Are personality and 'level' the same thing? Is "linear" mode represented > as 1? linear == -1. Different personalities impliment different levels. personality raid5 implements levels 4 and 5. > > So many variables here... I want to give this a shot, but I also don't > want to trash my system doing something stupid! You learn by making mistakes... live a little!!! > > One more question... I seem to remember that you can only have something > like 12 or 27 devices per set a while back. Does this limitation still > stand for non-superblock linear raids? If so, will I be able to > effectively use more devices by creating multiple raids of 12 devices, and > then making a raid of the raids? 27 on recent kernels. Limit still applies with non-superblock. You could do a raid of 27 arrays each with 27 devices if you like. NeilBrown > > Thanks for your help! > -Jeff > > - > To unsubscribe from this list: send the line "unsubscribe linux-raid" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
