+++ This bug was introduced by the fix for Bug #1533161 +++ Description of problem: Free_disk_gb becomes negative when over-commit is enabled and available disk space is consumed by launching multiple VMs Version-Release number of selected component (if applicable): python-nova-16.0.2-8.el7ost.noarch How reproducible: Always Steps to Reproduce: 1. Launch VMs to consume available disk space and exceed it (overcloud) [stack@undercloud-0 ~]$ openstack server list +--------------------------------------+-----------+--------+-----------------+--------+-----------+ | ID | Name | Status | Networks | Image | Flavor | +--------------------------------------+-----------+--------+-----------------+--------+-----------+ | 3f4a0d5f-4485-445a-a437-4f7ee7cf96d4 | test_vm_4 | ACTIVE | nova=10.0.0.212 | CirrOS | m1.custom | | 7964db7d-c587-4a94-9645-f54bd995c242 | test_vm_3 | ACTIVE | nova=10.0.0.213 | CirrOS | m1.custom | | 9f8b15aa-a761-4f68-908a-bfa89806a949 | test_vm_2 | ACTIVE | nova=10.0.0.214 | CirrOS | m1.custom | | 78ff31c3-433a-4e50-bac6-6c4bf86e7aca | test_vm | ACTIVE | nova=10.0.0.219 | CirrOS | m1.custom | +--------------------------------------+-----------+--------+-----------------+--------+-----------+ 2. free_disk_gb becomes negative: (overcloud) [stack@undercloud-0 ~]$ nova hypervisor-show 7c7afcb3-a7fe-4ff1-8f86-e1f0875392da +---------------------------+------------------------------------------+ | Property | Value | +---------------------------+------------------------------------------+ | cpu_info_arch | x86_64 | | cpu_info_features | ["pge", "avx", "xsaveopt", "clflush", | | | "sep", "syscall", "tsc-deadline", | | | "invpcid", "tsc", "fsgsbase", "xsave", | | | "vmx", "erms", "cmov", "smep", "fpu", | | | "pat", "lm", "msr", "nx", "fxsr", | | | "sse4.1", "pae", "sse4.2", "pclmuldq", | | | "pcid", "fma", "vme", "mmx", "osxsave", | | | "cx8", "mce", "de", "aes", "mca", "pse", | | | "lahf_lm", "abm", "popcnt", "pdpe1gb", | | | "apic", "sse", "f16c", "pni", "rdtscp", | | | "avx2", "sse2", "ss", "hypervisor", | | | "bmi1", "bmi2", "ssse3", "cx16", | | | "pse36", "mtrr", "movbe", "rdrand", | | | "x2apic"] | | cpu_info_model | Haswell-noTSX | | cpu_info_topology_cells | 1 | | cpu_info_topology_cores | 1 | | cpu_info_topology_sockets | 2 | | cpu_info_topology_threads | 1 | | cpu_info_vendor | Intel | | current_workload | 0 | | disk_available_least | -9 | | free_disk_gb | -3 | | free_ram_mb | 1023 | | host_ip | 172.17.1.18 | | hypervisor_hostname | compute-1.localdomain | | hypervisor_type | QEMU | | hypervisor_version | 2009000 | | id | 7c7afcb3-a7fe-4ff1-8f86-e1f0875392da | | local_gb | 19 | | local_gb_used | 22 | | memory_mb | 6143 | | memory_mb_used | 5120 | | running_vms | 2 | | service_disabled_reason | None | | service_host | compute-1.localdomain | | service_id | 4f27375f-1b51-49be-81c8-bbeeca36dedc | | state | up | | status | enabled | | vcpus | 2 | | vcpus_used | 2 | +---------------------------+------------------------------------------+ Actual results: free_disk_gb is negative Expected results: free_disk_gb should be positive Additional info:
This looks weird, but it's actually accurate. It's reporting the amount of free disk space available to an unprivileged user (e.g. the Nova user), which on this system is -3GB, because we've used all unreserved space and 3GB of reserved space. See 'tune2fs -m' for details. Incidentally, although I'm closing this bug I've created bug 1536375 to track the incorrect disk space check during live migration.
I might suggest that if the intent is to show space available to the unpriviledged users, you might clamp the value at 0 to avoid confusion with the negative numbers.