github.com/xhghs/rclone@v1.51.1-0.20200430155106-e186a28cced8/vfs/help.go (about)

     1  package vfs
     2  
     3  // Help contains text describing file and directory caching to add to
     4  // the command help.
     5  var Help = `
     6  ### Directory Cache
     7  
     8  Using the ` + "`--dir-cache-time`" + ` flag, you can set how long a
     9  directory should be considered up to date and not refreshed from the
    10  backend. Changes made locally in the mount may appear immediately or
    11  invalidate the cache. However, changes done on the remote will only
    12  be picked up once the cache expires.
    13  
    14  Alternatively, you can send a ` + "`SIGHUP`" + ` signal to rclone for
    15  it to flush all directory caches, regardless of how old they are.
    16  Assuming only one rclone instance is running, you can reset the cache
    17  like this:
    18  
    19      kill -SIGHUP $(pidof rclone)
    20  
    21  If you configure rclone with a [remote control](/rc) then you can use
    22  rclone rc to flush the whole directory cache:
    23  
    24      rclone rc vfs/forget
    25  
    26  Or individual files or directories:
    27  
    28      rclone rc vfs/forget file=path/to/file dir=path/to/dir
    29  
    30  ### File Buffering
    31  
    32  The ` + "`--buffer-size`" + ` flag determines the amount of memory,
    33  that will be used to buffer data in advance.
    34  
    35  Each open file descriptor will try to keep the specified amount of
    36  data in memory at all times. The buffered data is bound to one file
    37  descriptor and won't be shared between multiple open file descriptors
    38  of the same file.
    39  
    40  This flag is a upper limit for the used memory per file descriptor.
    41  The buffer will only use memory for data that is downloaded but not
    42  not yet read. If the buffer is empty, only a small amount of memory
    43  will be used.
    44  The maximum memory used by rclone for buffering can be up to
    45  ` + "`--buffer-size * open files`" + `.
    46  
    47  ### File Caching
    48  
    49  These flags control the VFS file caching options.  The VFS layer is
    50  used by rclone mount to make a cloud storage system work more like a
    51  normal file system.
    52  
    53  You'll need to enable VFS caching if you want, for example, to read
    54  and write simultaneously to a file.  See below for more details.
    55  
    56  Note that the VFS cache works in addition to the cache backend and you
    57  may find that you need one or the other or both.
    58  
    59      --cache-dir string                   Directory rclone will use for caching.
    60      --vfs-cache-max-age duration         Max age of objects in the cache. (default 1h0m0s)
    61      --vfs-cache-mode string              Cache mode off|minimal|writes|full (default "off")
    62      --vfs-cache-poll-interval duration   Interval to poll the cache for stale objects. (default 1m0s)
    63      --vfs-cache-max-size int             Max total size of objects in the cache. (default off)
    64  
    65  If run with ` + "`-vv`" + ` rclone will print the location of the file cache.  The
    66  files are stored in the user cache file area which is OS dependent but
    67  can be controlled with ` + "`--cache-dir`" + ` or setting the appropriate
    68  environment variable.
    69  
    70  The cache has 4 different modes selected by ` + "`--vfs-cache-mode`" + `.
    71  The higher the cache mode the more compatible rclone becomes at the
    72  cost of using disk space.
    73  
    74  Note that files are written back to the remote only when they are
    75  closed so if rclone is quit or dies with open files then these won't
    76  get written back to the remote.  However they will still be in the on
    77  disk cache.
    78  
    79  If using --vfs-cache-max-size note that the cache may exceed this size
    80  for two reasons.  Firstly because it is only checked every
    81  --vfs-cache-poll-interval.  Secondly because open files cannot be
    82  evicted from the cache.
    83  
    84  #### --vfs-cache-mode off
    85  
    86  In this mode the cache will read directly from the remote and write
    87  directly to the remote without caching anything on disk.
    88  
    89  This will mean some operations are not possible
    90  
    91    * Files can't be opened for both read AND write
    92    * Files opened for write can't be seeked
    93    * Existing files opened for write must have O_TRUNC set
    94    * Files open for read with O_TRUNC will be opened write only
    95    * Files open for write only will behave as if O_TRUNC was supplied
    96    * Open modes O_APPEND, O_TRUNC are ignored
    97    * If an upload fails it can't be retried
    98  
    99  #### --vfs-cache-mode minimal
   100  
   101  This is very similar to "off" except that files opened for read AND
   102  write will be buffered to disks.  This means that files opened for
   103  write will be a lot more compatible, but uses the minimal disk space.
   104  
   105  These operations are not possible
   106  
   107    * Files opened for write only can't be seeked
   108    * Existing files opened for write must have O_TRUNC set
   109    * Files opened for write only will ignore O_APPEND, O_TRUNC
   110    * If an upload fails it can't be retried
   111  
   112  #### --vfs-cache-mode writes
   113  
   114  In this mode files opened for read only are still read directly from
   115  the remote, write only and read/write files are buffered to disk
   116  first.
   117  
   118  This mode should support all normal file system operations.
   119  
   120  If an upload fails it will be retried up to --low-level-retries times.
   121  
   122  #### --vfs-cache-mode full
   123  
   124  In this mode all reads and writes are buffered to and from disk.  When
   125  a file is opened for read it will be downloaded in its entirety first.
   126  
   127  This may be appropriate for your needs, or you may prefer to look at
   128  the cache backend which does a much more sophisticated job of caching,
   129  including caching directory hierarchies and chunks of files.
   130  
   131  In this mode, unlike the others, when a file is written to the disk,
   132  it will be kept on the disk after it is written to the remote.  It
   133  will be purged on a schedule according to ` + "`--vfs-cache-max-age`" + `.
   134  
   135  This mode should support all normal file system operations.
   136  
   137  If an upload or download fails it will be retried up to
   138  --low-level-retries times.
   139  `