ndctl create-namespace doesn't walk through the regions from lowest to highest; in this example it's going 1,3,5,0,2,4,6: $ sudo ndctl create-namespace --verbose ROB: parsing bus id=0 path=ndbus0 ROB: parsing region id=1 path=region1 namespace_create:770: region1: insufficient capacity size: 0 avail: 0 ROB: parsing region id=3 path=region3 namespace_create:770: region3: insufficient capacity size: 0 avail: 0 ROB: parsing region id=5 path=region5 namespace_create:770: region5: insufficient capacity size: 0 avail: 0 ROB: parsing region id=0 path=region0 namespace_create:770: region0: insufficient capacity size: 0 avail: 0 ROB: parsing region id=2 path=region2 That makes the results unpredictable. That's from do_xaction_namespace(): ndctl_bus_foreach(ctx, bus) { printf("ROB: parsing bus id=%d path=%s\n", ndctl_bus_get_id(bus), ndctl_bus_get_devname(bus)); if (!util_bus_filter(bus, param.bus)) continue; ndctl_region_foreach(bus, region) { printf("ROB: parsing region id=%d path=%s\n", ndctl_region_get_id(region), ndctl_region_get_devname(region)); if (!util_region_filter(region, param.region)) The same order is used for other commands like disable-namespace and destroy-namespace. Questions ========= 1. Could the busses and regions (anything accessed with a _foreach() macro) be sorted in ascending order so this and other commands are more predictable? 2. For create-namespace with no region arguments, rather than just creating one random namespace, how about creating namespaces on each available region? 3. The manpage suggests that "-r all" does that, but it seems to just make every region number pass the filter in that foreach loop (i.e., it has no effect for the create-namespace command, which just creates one and quits). --- Robert Elliott, HPE Persistent Memory