How to free up space after using snapshots?

[ma3252788]

Required information

• Distribution:Ubuntu
• Distribution version: ubuntu 16.04
• The output of "lxc info" or if that fails:

  config:
  core.https_address: '[::]:8443'
  core.trust_password: true
  api_extensions:
  - storage_zfs_remove_snapshots
  - container_host_shutdown_timeout
  - container_stop_priority
  - container_syscall_filtering
  - auth_pki
  - container_last_used_at
  - etag
  - patch
  - usb_devices
  - https_allowed_credentials
  - image_compression_algorithm
  - directory_manipulation
  - container_cpu_time
  - storage_zfs_use_refquota
  - storage_lvm_mount_options
  - network
  - profile_usedby
  - container_push
  - container_exec_recording
  - certificate_update
  - container_exec_signal_handling
  - gpu_devices
  - container_image_properties
  - migration_progress
  - id_map
  - network_firewall_filtering
  - network_routes
  - storage
  - file_delete
  - file_append
  - network_dhcp_expiry
  - storage_lvm_vg_rename
  - storage_lvm_thinpool_rename
  - network_vlan
  - image_create_aliases
  - container_stateless_copy
  - container_only_migration
  - storage_zfs_clone_copy
  - unix_device_rename
  - storage_lvm_use_thinpool
  - storage_rsync_bwlimit
  - network_vxlan_interface
  - storage_btrfs_mount_options
  - entity_description
  - image_force_refresh
  - storage_lvm_lv_resizing
  - id_map_base
  - file_symlinks
  - container_push_target
  - network_vlan_physical
  - storage_images_delete
  - container_edit_metadata
  - container_snapshot_stateful_migration
  - storage_driver_ceph
  - storage_ceph_user_name
  - resource_limits
  - storage_volatile_initial_source
  - storage_ceph_force_osd_reuse
  - storage_block_filesystem_btrfs
  - resources
  - kernel_limits
  - storage_api_volume_rename
  - macaroon_authentication
  - network_sriov
  - console
  - restrict_devlxd
  - migration_pre_copy
  - infiniband
  - maas_network
  - devlxd_events
  - proxy
  - network_dhcp_gateway
  - file_get_symlink
  - network_leases
  - unix_device_hotplug
  - storage_api_local_volume_handling
  - operation_description
  - clustering
  - event_lifecycle
  - storage_api_remote_volume_handling
  - nvidia_runtime
  - candid_authentication
  - candid_config
  - candid_config_key
  - usb_optional_vendorid
  api_status: stable
  api_version: "1.0"
  auth: trusted
  public: false
  auth_methods:
  - tls
  environment:
  addresses:
  - 172.25.17.68:8443
  - '[2001:da8:216:2511:60f9:2f94:f4de:83e8]:8443'
  - '[2001:da8:216:2511:d5ee:2398:915a:f862]:8443'
  - '[2001:da8:216:2511:69cd:139b:4cae:35c0]:8443'
  - '[2001:da8:216:2511:ae1f:6bff:fe7c:6fa3]:8443'
  - 10.124.46.1:8443
  - '[fd42:3aa8:1d6f:a4f8::1]:8443'
  architectures:
  - x86_64
  - i686
  certificate: |
  -----BEGIN CERTIFICATE-----
  MIIFaDCCA1CgAwIBAgIRALhuzLf2LlB5pAmUXXPMBWMwDQYJKoZIhvcNAQELBQAw
  NTEcMBoGA1UEChMTbGludXhjb250YWluZXJzLm9yZzEVMBMGA1UEAwwMcm9vdEBt
  Y2oyMDgwMB4XDTE5MDUzMDA2MTYyOFoXDTI5MDUyNzA2MTYyOFowNTEcMBoGA1UE
  ChMTbGludXhjb250YWluZXJzLm9yZzEVMBMGA1UEAwwMcm9vdEBtY2oyMDgwMIIC
  IjANBgkqhkiG9w0BAQEFAAOCAg8AMIICCgKCAgEAs6EgWqBughFTEND90eubPOqW
  e5A7pL0gWPKQxepyWk5NdNLbefkeIrqXwgxlUvp8glFoRb2qzyReESij14zC0y/g
  CdMGid35yYd6HfsW0YwoMLlKGMvWybn6Ic6eFi6ypPWnBdNUueyhVqozNf5Lt3+Y
  npTIIG5mZ7Iv5FeT+75k/AtDzKIXYgdE4YVpJqppR47ZnfTMbSrJCUQOnxzf1PFI
  mj+T9XPYx+v2Jl/bWE7iiNU82FFKcvAP40CK6udS6kQV8IZb0CecRa9kA8OK1yQ5
  NbpNwsvb4OxXMUkOGU5fL4ZAmQ8mH2n7Tbnk677jbDAjg5xt+O5vaPXMuS5M/pVk
  WeGzJPE2qSysDVdZhvGBwEvLnUjnKFYPmX2a/DRFyQjEtkuhifyKju18IQDYzwan
  CrAPdTKz79RYnH9XpF1uXiJQzcj/aZX+mEeHU38pplFcXKarH9RU/q17K4jwvqtJ
  1bM4LuOTaqLEhqziaNi/3ZuPAjAbT8/emq2gjCyFHBGA8M+/sWvYpAKzJRN7TzfE
  42VmRByhtNEkzdUgF28ZMmSYI5rje+Lbr5tNNOh8srwk5+rTCxdyIiDqrlJbHyw3
  6kIRmy3faEi0Flme5nYwzWQiN0LrcM8WbsUJQ42NUGgnU57zzNvx34NGBmDuthZV
  AXOMiBgHpzaxnJSDd1cCAwEAAaNzMHEwDgYDVR0PAQH/BAQDAgWgMBMGA1UdJQQM
  MAoGCCsGAQUFBwMBMAwGA1UdEwEB/wQCMAAwPAYDVR0RBDUwM4IHbWNqMjA4MIcE
  rBkRJ4cQIAENqAIWJRE8hATl22ORvIcQIAENqAIWJRFknTw0SMPwAzANBgkqhkiG
  9w0BAQsFAAOCAgEAQm1uEHHQfsTlJ4qKw3cbdSRzdXydWUTKODwqLa8jwO0ZAeMN
  Iloqt+Vl3EA/rcYL82RzHb9GjsZES2FQaFwRHqqya+Dc1l6j4FWmprnIXj2K4XFF
  5MK3uzwAXDMrMwtnzyBOByA0EP8wcmhjD/gch8LQ75dXWzjZDTACLRboCEaFQO4A
  M0hgqg12yIK9YOtdbgaSFlDrQW0caxUh4LqqDuquMnCtHkrPvskmTw5VkKCVntMV
  KsxzvmvCB30+JAiborXTLukcQ5Tp+lku/CxKkU7XncPwTvblWk8SGuzBcBlqQgla
  TIPj3VwYQs0/bbKCMC6voo8Qb4i2/L5ieq3PwpxV8bIlc/O8EED+IYkfVtLTnGBN
  D7hbS+gZqomS7GOxwPpygKaFS/9yA9hsPS8mOIeJqXO3Wh2hfZzHF7mSx58FFGAp
  Uegx6B40Poz41JRWoQDIBst6f/3FgbCrRS3o7fq4toJPvBkiMyvce437KMKa8+uB
  CXeE5El16Bz5q1UFcVb5LbsvKhbb7cry8VdIR5BYviQPjFrQEqRPkkR51jYjjWpc
  qy48u+R11i0Ih59rwjQITrjdERPiFyjyDIZPYRbvsoMHFKmcSpeHhLXe36eoj4YY
  wcbbSu2JxScA8/5sXiv4v+aq8KyhdZOrkw08Y8KFfjPrObtEowT1TMUZxAY=
  -----END CERTIFICATE-----
  certificate_fingerprint: df9859335b5fca7e6702d5fed601ea614ebf1aab84d2e16f4bb4d34503a262f2
  driver: lxc
  driver_version: 3.0.3
  kernel: Linux
  kernel_architecture: x86_64
  kernel_version: 4.15.0-142-generic
  server: lxd
  server_pid: 3158
  server_version: 3.0.3
  storage: zfs
  storage_version: 0.7.5-1ubuntu16.11
  server_clustered: false
  server_name: mcj2080
  project: ""

Issue description

At some point in the past, I took a snapshot of a container, and recently when I was organizing the container, I noticed that the space inside the container was not freed up after the files were deleted, and I think this is because I took a snapshot before. How do I properly free up my hard drive space? Just delete all the previous snapshots?

Steps to reproduce

1. lxc snapshot part1 snapname
2. lxc exec part1 bash
3. delele some files, however, the free space does not decrease after running the df -h command

Information to attach

• [ ] Container log (lxc info NAME --show-log)

  
  Name: part1
  Remote: unix://
  Architecture: x86_64
  Created: 2019/11/10 12:13 UTC
  Status: Running
  Type: persistent
  Profiles: default
  Pid: 15563
  Ips:
  docker0:      inet    172.17.0.1
  eth0: inet    172.25.17.208   vethRV0SKY
  eth0: inet6   2001:da8:216:2511:216:3eff:fe3a:f98     vethRV0SKY
  eth0: inet6   fe80::216:3eff:fe3a:f98 vethRV0SKY
  lo:   inet    127.0.0.1
  lo:   inet6   ::1
  Resources:
  Processes: 874
  Disk usage:
  root: 772.07GB
  CPU usage:
  CPU usage (in seconds): 158479
  Memory usage:
  Memory (current): 15.00GB
  Memory (peak): 29.37GB
  Network usage:
  lo:
    Bytes received: 67.47kB
    Bytes sent: 67.47kB
    Packets received: 804
    Packets sent: 804
  docker0:
    Bytes received: 0B
    Bytes sent: 0B
    Packets received: 0
    Packets sent: 0
  eth0:
    Bytes received: 7.31GB
    Bytes sent: 360.02GB
    Packets received: 52014289
    Packets sent: 25544147
  Snapshots:
  bak1 (taken at 2019/11/10 12:13 UTC) (stateless)
  mcj20190902 (taken at 2019/11/10 12:13 UTC) (stateless)
  20191213 (taken at 2019/12/13 03:48 UTC) (stateless)
  20191220 (taken at 2019/12/20 03:57 UTC) (stateless)
  20191220v2 (taken at 2019/12/20 09:42 UTC) (stateless)
  20191224 (taken at 2019/12/24 08:53 UTC) (stateless)
  20200426 (taken at 2020/04/26 14:38 UTC) (stateless)
  20200728ECANET (taken at 2020/07/28 12:02 UTC) (stateless)
  20200802 (taken at 2020/08/02 14:04 UTC) (stateless)
  20200807 (taken at 2020/08/06 16:04 UTC) (stateless)
  20200821 (taken at 2020/08/21 08:22 UTC) (stateless)
  todln (taken at 2020/09/05 13:29 UTC) (stateless)
  20200911 (taken at 2020/09/11 04:05 UTC) (stateless)
  k1 (taken at 2020/09/12 14:24 UTC) (stateless)
  bak (taken at 2020/09/16 14:58 UTC) (stateless)
  20200918 (taken at 2020/09/18 01:56 UTC) (stateless)
  20200918-1 (taken at 2020/09/18 02:04 UTC) (stateless)
  before_orn (taken at 2020/09/23 09:12 UTC) (stateless)
  20201111 (taken at 2020/11/11 08:55 UTC) (stateless)
  20201208 (taken at 2020/12/08 09:15 UTC) (stateless)

Log:

lxc part1 20210817010616.705 WARN conf - conf.c:lxc_setup_devpts:1616 - Invalid argument - Failed to unmount old devpts instance

 - [ ] Container configuration (`lxc config show NAME --expanded`)

architecture: x86_64 config: image.architecture: x86_64 image.description: Ubuntu 16.04 LTS server (20181207) image.os: ubuntu image.release: xenial security.privileged: "true" volatile.base_image: ed24e99183897c62fad305b6f2257c33c1cb457f6d59a970b421046e8f94481f volatile.eth1.hwaddr: 00:16:3e:3a:0f:98 volatile.eth1.name: eth0 volatile.idmap.base: "0" volatile.idmap.next: '[]' volatile.last_state.idmap: '[]' volatile.last_state.power: RUNNING devices: eth1: nictype: bridged parent: br1 type: nic gpu: type: gpu nvidia-uvm: path: /dev/nvidia-uvm type: unix-char root: path: / pool: lxd-zfs type: disk share: path: /home/ubuntu/bigdisk source: /home/mcj/bigdisk type: disk ephemeral: false profiles:

• default stateful: false description: ""

[stgraber]

Closing as this is a support question and not really an issue (nothing actionable for us). In general those are better handled at https://discuss.linuxcontainers.org

But yes, you're correct, a snapshot is always free at the time it's taken but becomes costly overtime as the state diverges. If you create an instance with 2GB of data, you make a snapshot and then proceed to delete that 2GB of data. The size will still be 2GB as the snapshot is preventing it from getting actually released.