ZFS Clone Manager

Tool to add version control and historic data of a directory with ZFS. The functionality is similar to Solaris beadm but generalized for any ZFS filesystem, not just ROOT and VAR.

The suggested workflow is:

1. Initialize a manager (zcm init)
2. Make changes in active clone
3. Create new clone (zcm clone)
4. Make changes in new clone
5. Activate new clone (zcm activate)
6. [Remove older clones (zcm rm)]
7. Go to step 2

Usage

• Initialize a ZCM manager

  $ zcm init rpool/directory /directory
  ZCM initialized ZFS rpool/directory at path /directory

  "rpool/directory" -> root of the ZFS for clones and snapshots. "/directory" -> path of the filesystem (mountpoint of the active clone).

• Show ZCM information

  $ zcm info /directory
  Path: /directory
  Root ZFS: rpool/directory
  Root ZFS size: 63.00 KB
  Total clone count: 1
  Older clone count: 0
  Newer clone count: 0
  Oldest clone ID: 00000000
  Active clone ID: 00000000
  Newest clone ID: 00000000
  Next clone ID: 00000001
  
  $ zcm ls /directory
  MANAGER          A  ID        CLONE                     MOUNTPOINT  ORIGIN    DATE                 SIZE    
  rpool/directory     00000001  rpool/directory/00000000  /directory            2021-02-16 10:46:59  32.00 KB

• Create new clones (derived from active)

  $ zcm clone /directory
  Created clone 00000001 at path /directory/.clones/00000001
  $ zcm clone /directory
  Created clone 00000002 at path /directory/.clones/00000002
  $ zcm ls /directory
  MANAGER          A  ID        CLONE                     MOUNTPOINT                   ORIGIN    DATE                 SIZE    
  rpool/directory  *  00000000  rpool/directory/00000000  /directory                             2021-02-20 06:51:14  32.00 KB
  rpool/directory     00000001  rpool/directory/00000001  /directory/.clones/00000001  00000000  2021-02-20 06:57:01  18.00 KB
  rpool/directory     00000002  rpool/directory/00000002  /directory/.clones/00000002  00000000  2021-02-20 06:57:02  18.00 KB

• Activate the previously created clone, mounting it at ZCM path

  $ zcm activate /directory 00000002
  Activated clone 00000002

  The activate command can not be executed from inside the path, therefore the parameter -p is mandatory.

• All the clones are visible at /.clones

  $ ls /directory/.clones
  0000000 00000001 00000002

• Show differences of a clone from it's origin

  $ mkdir /directory/tmp
  $ mkfile 10m /directory/tmp/file
  $ zcm diff /directory
  MOUNTPOINT  DATE                        CHANGE    FILE      FILE_TYPE
  /directory  2021-02-22 06:19:34.094470  Modified  .         directory
  /directory  2021-02-22 06:21:07.236145  Added     tmp       directory
  /directory  2021-02-22 06:21:07.309059  Added     tmp/file  file     

• Remove clones

  $ zcm rm /directory 00000001
  WARNING!!!!!!!!
  All the filesystems, snapshots and directories associated with clone 00000001 will be permanently deleted.
  This operation is not reversible.
  Do you want to proceed? (yes/NO) yes
  Removed clone 00000001

• Destroy ZCM related data

  This is dangerous, you should backup data first.

  $ zcm destroy /directory
  WARNING!!!!!!!!
  All the filesystems, clones, snapshots and directories associated with rpool/directory will be permanently deleted.
  This operation is not reversible.
  Do you want to proceed? (yes/NO) yes
  Destroyed ZCM rpool/directory

• Initialize a ZCM manager based on an existing directory:

  $ zcm ls /directory
  There is no ZCM manager at /directory
  $ mkdir -p /directory/tmp
  $ mkfile 10m /directory/tmp/file
  $ zcm init -M rpool/directory /directory
  ZCM initialized ZFS rpool/directory at path /directory
  $ zcm ls rpool/directory
  MANAGER          A  ID        CLONE                     MOUNTPOINT  ORIGIN  DATE                 SIZE    
  rpool/directory  *  00000000  rpool/directory/00000000  /directory          2021-02-22 13:37:28  10.04 MB
  $ ls /directory
  .clones/ tmp/     
  $ ls /directory/tmp
  file

• Initialize a ZCM manager based on an existing ZFS:

  $ zfs create -o mountpoint=/directory rpool/directory
  $ mkdir /directory/tmp
  $ mkfile 10m /directory/tmp/file
  $ zcm init -m rpool/directory /directory
  ZCM initialized ZFS rpool/directory at path /directory
  $ zcm ls rpool/directory
  MANAGER          A  ID        CLONE                     MOUNTPOINT  ORIGIN  DATE                 SIZE    
  rpool/directory  *  00000000  rpool/directory/00000000  /directory          2021-02-22 13:39:43  10.04 MB
  $ ls /directory 
  tmp
  $ ls /directory/tmp
  file