vchanger/ReleaseNotes

 Release Notes for vchanger 1.0.3                  2020-05-07

 Release 1.0.3
 
 This is mostly a bug fix release, correcting the number of slots
 reported by SIZE/LIST commands, a compilation error on FreeBSD,
 and failure of the launch scripts invoked by udev on some platforms.
 
 The locking mechanism to allow multiple instances and automatically
 issuing 'update slots' and other commands to bconsole has been
 redesigned to use POSIX semaphores.
 
 Bugs Fixed:
     17 SIZE/​LIST commands return wrong number of slots
     18 Compilation fails on FreeBSD 13 (head)
 
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 Release 1.0.2
 
 This is a bug fix release, fixing three issues found in version 1.0.1
 and improving volume label formatting for CREATEVOLS command and logging
 of udev/UUID mountpoint discovery.

 Bugs Fixed:

     13  LOAD command allows loading slot into multiple drives
     14  Hang when bconsole called to update slots
     15  Race condition in bconsole call may hang vchanger

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 Release 1.0.1
 
 This is a bug fix release, fixing four issues found in version 1.0.0.
 Additionally, the Windows installer was fixed to correctly install on
 64-bit Windows and create Start Menu items.

 Bugs Fixed:

      9  Vchanger may hang when issuing commands to Bacula
     10  uuidlookup.c compilation failure on FreeBSD 9.3
     11  Missing libwinpthread-1.dll error in Windows version
     12  Mounted magazines specified by UUID not always detected

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 Release 1.0.0

 This is a major release adding several features and a change in the  
 structure of magazines and the way volume files are "loaded" into  
 virtual drives. These changes allow for an unlimited and variable 
 number  of volume files on each magazine, and allow adding and deleting  
 volumes to/from magazines, as well as moving volume files from one  
 magazine to another. Virtual drives are now symlinks dynamically 
 created  by the LOAD command. An unlimited number of virtual drives per 
 autochanger  is supported without requiring a vchanger configuration 
 change. The  number of virtual drives used is determined solely by the 
 Device resources  defined in bacula-sd.conf.
 
 Also, vchanger will now automatically issue 'update slots' and
 'label barcodes' commands to Bacula via bconsole when it detects a
 change in the availability of any of its defined magazines or when
 volume files are created with the CREATEVOLS command. Together with
 an automounting mechanism, this makes the attachment and detachment
 of removable drives a plug-n-play operation.
 
 To aid in using removable drives on systems having udev, vchanger now
 includes a udev rules generator and helper scripts to enable the
 automatic mounting of magazine filesystems triggered by udev hotplug
 events. The advantage to using this automounting method, as opposed to
 autofs or window manager automounters using dbus, etc., is that these
 scripts will invoke vchanger with a new REFRESH command that will issue
 an 'update slots' command via bconsole whenever removable drives
 are attached or detached.
 
 Change Summary:
 
 The concept of a 'magazine' has changed. A magazine remains a 
 directory,   usually the mountpoint of a filesystem, however no metadata 
 files are  now  stored on the magazines and volume files are not renamed 
 when loading  and  unloading virtual drives. There is now no requirement 
 that all  magazines  have the same number of volumes, and volume files 
 may have any  filename.  New volume files can be created on a magazine 
 at any time. A  new extended  interface command, CREATEVOLS, has been 
 implemented for this  purpose. A  magazine is now simply a filesystem 
 (or directory) containing  some  variable number of volume files. Any 
 directory containing volume  files  can be used as a magazine in 
 vchanger, including for example  volumes  created using Bacula's 
 built-in disk storage handling. Volume files may  be deleted from 
 magazines or moved between magazines. The only caveat is  that the 
 volume's Media Type must match that of the autochanger's  Storage 
 resource.

 Virtual drives are now simply a symlink in the autochanger's work 
 directory. The  drive number is the name of the symlink. For example,
 if the autochanger's  work directory is /var/spool/vchanger/changer1,
 then virtual drive 0 is a  symlink at the path 
 /var/spool/vchanger/changer1/0. The symlink's path is  then specified as 
 the Archive Device in the Device resource defined in  bacula-sd.conf for 
 the autochanger's drive 0. Vchanger implements the LOAD  command by 
 creating this symlink pointing at the volume file mapped to the  slot 
 requested to be loaded. A subsequent UNLOAD command deletes the  
 symlink. In previous versions, a LOAD created a symlink pointing to the  
 mountpoint of the magazine and then renamed the volume file on the  
 magazine to 'drive0', 'drive1', etc. This was because the original 
 design  criteria, (dating to before the release of Bacula 2.0.0), 
 required that vchanger run on Windows Server 2003, which did not have 
 the capability of file-level symlinks. However, file-level symlinks is 
 a much more robust method, handling any "out of space" conditions in a 
 clean, expected way. For that reason, use of vchanger on versions of 
 Windows without file-level symlinks is no longer supported.
 
 An autochanger's magazines are assigned in its vchanger configuration
 file. An unlimited number of magazines is supported and the storage space used
 by an autochanger can be scaled at any time by simply adding additional
 magazines and creating volume files on them. Expansion of the storage
 space does not require any change to Bacula's configuration. Any
 combination of one or more of the assigned magazines can be attached
 (mounted) at any time. 
 
 When a magazine is attached or detached there is of course a change in
 which volumes are available for reading and writing. Bacula must be
 instructed to update its database to reflect the change. This is
 analogous to swapping tapes in a tape autochanger library. Bacula has a
 bconsole command used for this purpose, the 'update slots' command. In
 general, one would insert or remove tapes and then issue an 'update slots'
 command in bconsole to inform Bacula of the change. With vchanger,
 attaching or detaching a magazine also requires that the 'update slots'
 command be issued, however vchanger now detects changes to the currently
 available volume files and automatically issues the 'update slots'
 command when needed. This allows swapping magazines to be a true
 plug-n-play operation.
 
 The scripts directory in the vchanger source tree contains a script to
 generate the udev rules needed to automatically mount the magazines
 filesystems defined in the vchanger configuration file. These rules will
 cause udev to launch scripts, also included in the scripts directory, to
 handle a "hot add" event by mounting the magazine filesystem and invoking
 vchanger with the REFRESH command to issue an 'update slots' command to
 Bacula. Likewise, a "hot delete" event will launch a script to unmount
 the filesystem and again invoke vchanger with the REFRESH command.
 
 If vchanger is compiled on a system supporting udev, then libudev will be  
 used to determine the device node of magazine partitions specified by  
 UUID. If compiled on a system without udev, the older method of using 
 libblkid and  libuuid will be used if available. For Windows builds, 
 win32 API functions are used to map filesystem UUID to device node. If
 the getmntent() function is not available on the target system for
 determining a filesystem's mountpoint, then vchanger will use the
 getfsstat() function, allowing magazines to be specified by UUID on many
 BSD and OSX systems. A build for a minimal system having neither libudev
 nor libblkid will succeed, however specifying magazines by UUID will not
 function and result in an error, meaning that such minimal systems must
 only specify magazines by directory path. These changes should alleviate
 many of the problems people have had in the past building vchanger for
 non-Linux systems. 
 
 Bugs Fixed:
      5  Compile errors on Debian or Ubuntu
      6  Broken libblkid returns wrong device for UUID
      7  Limitation on number of virtual drives
      8  Compile errors under Solaris 10

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 Release 0.8.6

 When using the automount_dir directive, opendir() is now used rather 
 than  stat(), to trigger automounts. For some combinations of Linux 
 kernel and older  versions of autofs, stat() is not sufficient to 
 trigger an automount.

 Extensive logging was added to this version, along with a new 
 configuration  directive to set the logging level. This should greatly 
 help problem diagnosis.

 State information for the magazine bays is now kept in the work 
 directory  along with virtual drive state. In a multi-magazine changer, 
 when a magazine  was unloaded from a bay, magazines in higher numbered 
 bays were being shifted  down to appear loaded into a different bay 
 than they were before the magazine  was unloaded. With this version, 
 magazines will remain loaded in the same bay  until they are unloaded.

 Bugs Fixed:

 ==================================================================


 Release 0.8.5

 Minor bug fix release. Fixes link errors for older versions of 
 e2fsprogs on some  distros (bug 4). Also applies the "safe strncat" 
 patch to prevent a buffer  overrun present in strncat in some standard 
 C libraries.
 
 Bugs Fixed:
      4  Compile errors related to e2fsprogs libraries

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 Release 0.8.4

 This release is a bug fix release. All users of version 0.8.3 should 
 upgrade to  0.8.4 to prevent a bug causing Bacula to mark volumes in 
 error.

 Change Summary:
 The slot number passed in parameter 3 is now ignored for the LOADED 
 command. This should fix a bug causing Bacula to mark a volume 
 loaded into a drive in error when a job starts after the magazine 
 has been removed. 

 Bugs Fixed:
      3  LOADED command fails when param 3 (slot) is zero
      2  Compile fail on FreeBSD 7.2

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 Release 0.8.3

 This release adds the ability to specify magazine partitions by UUID,
 making it much easier to use multiple simultaneous magazines.
 
 Change Summary:

 Specifying magazine partitions by UUID is a paradigm shift in the way 
 magazines may be assigned to a particular autochanger. Previously, 
 magazines were assigned to an autochanger by giving the magazine a 
 filesystem label matching the autochanger's name. Standard udev 
 rules on many distributions create a device symlink in 
 /dev/disk/by-label that allow easily configuring autofs to mount the   
 magazine at a known mountpoint. This works well for a single magazine 
 autochanger, but for a multi-magazine autochanger special udev rules 
 are needed to create unique device symlinks when all of the 
 magazines have the same filesystem label. Since the standard udev 
 rules on most systems create device symlinks by filesystem UUID 
 under /dev/disk/by-uuid, assigning magazines to an autochanger by UUID 
 makes it much easier to configure automounting that will work for an 
 autochanger with any number of simultaneously mounted magazines.
  
 Note that magazines may still be specified as a directory path, so the 
 previous methods still work, however it is recommended to assign 
 magazines by UUID if possible.
 
 As an aid to working with multi-magazine autochangers, a new extended 
 API command, LISTMAGS, was added to list the magazines currently 
 "inserted" into each of the autochanger's magazine bays. Like the 
 INITMAG command, it is an extension to the Bacula Autochanger API and so 
 is never invoked by Bacula.

 Bugs Fixed:
      1  Unable to detect when drives inserted using the vchanger
      2  Compile fail on FreeBSD 7.2

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 Release 0.8.2
 
 This release fixes some documentation errors. No changes were
 made to the vchanger source.
 
 Change Summary:
 2009-04-14
  - Fixed ambiguities in the Howto kindly pointed out by Sean Brannon.
 2009-01-27
  - Added command line flags to set uid and gid when run as root
  - Force LOADED command to return zero when no slot is loaded
  - Changed 99-by-label-fix.rules to work with centos5/el5
  - Added stateN files to track the loaded state of each virtual
    drive when last invoked
  - Removed debug line inadvertently left in by_label_fix.sh
 
 2008-10-03
 - This initial release has been running on a test server with
   Bacula 2.4.2 on Linux for over a week, so is considered beta.
 
 Bugs Fixed:
 
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