github.com/10XDev/rclone@v1.52.3-0.20200626220027-16af9ab76b2a/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 if the backend configured does not
    13  support polling for changes. If the backend supports polling, changes
    14  will be picked up on within the polling interval.
    15  
    16  Alternatively, you can send a ` + "`SIGHUP`" + ` signal to rclone for
    17  it to flush all directory caches, regardless of how old they are.
    18  Assuming only one rclone instance is running, you can reset the cache
    19  like this:
    20  
    21      kill -SIGHUP $(pidof rclone)
    22  
    23  If you configure rclone with a [remote control](/rc) then you can use
    24  rclone rc to flush the whole directory cache:
    25  
    26      rclone rc vfs/forget
    27  
    28  Or individual files or directories:
    29  
    30      rclone rc vfs/forget file=path/to/file dir=path/to/dir
    31  
    32  ### File Buffering
    33  
    34  The ` + "`--buffer-size`" + ` flag determines the amount of memory,
    35  that will be used to buffer data in advance.
    36  
    37  Each open file descriptor will try to keep the specified amount of
    38  data in memory at all times. The buffered data is bound to one file
    39  descriptor and won't be shared between multiple open file descriptors
    40  of the same file.
    41  
    42  This flag is a upper limit for the used memory per file descriptor.
    43  The buffer will only use memory for data that is downloaded but not
    44  not yet read. If the buffer is empty, only a small amount of memory
    45  will be used.
    46  The maximum memory used by rclone for buffering can be up to
    47  ` + "`--buffer-size * open files`" + `.
    48  
    49  ### File Caching
    50  
    51  These flags control the VFS file caching options.  The VFS layer is
    52  used by rclone mount to make a cloud storage system work more like a
    53  normal file system.
    54  
    55  You'll need to enable VFS caching if you want, for example, to read
    56  and write simultaneously to a file.  See below for more details.
    57  
    58  Note that the VFS cache works in addition to the cache backend and you
    59  may find that you need one or the other or both.
    60  
    61      --cache-dir string                   Directory rclone will use for caching.
    62      --vfs-cache-max-age duration         Max age of objects in the cache. (default 1h0m0s)
    63      --vfs-cache-mode string              Cache mode off|minimal|writes|full (default "off")
    64      --vfs-cache-poll-interval duration   Interval to poll the cache for stale objects. (default 1m0s)
    65      --vfs-cache-max-size int             Max total size of objects in the cache. (default off)
    66  
    67  If run with ` + "`-vv`" + ` rclone will print the location of the file cache.  The
    68  files are stored in the user cache file area which is OS dependent but
    69  can be controlled with ` + "`--cache-dir`" + ` or setting the appropriate
    70  environment variable.
    71  
    72  The cache has 4 different modes selected by ` + "`--vfs-cache-mode`" + `.
    73  The higher the cache mode the more compatible rclone becomes at the
    74  cost of using disk space.
    75  
    76  Note that files are written back to the remote only when they are
    77  closed so if rclone is quit or dies with open files then these won't
    78  get written back to the remote.  However they will still be in the on
    79  disk cache.
    80  
    81  If using --vfs-cache-max-size note that the cache may exceed this size
    82  for two reasons.  Firstly because it is only checked every
    83  --vfs-cache-poll-interval.  Secondly because open files cannot be
    84  evicted from the cache.
    85  
    86  #### --vfs-cache-mode off
    87  
    88  In this mode the cache will read directly from the remote and write
    89  directly to the remote without caching anything on disk.
    90  
    91  This will mean some operations are not possible
    92  
    93    * Files can't be opened for both read AND write
    94    * Files opened for write can't be seeked
    95    * Existing files opened for write must have O_TRUNC set
    96    * Files open for read with O_TRUNC will be opened write only
    97    * Files open for write only will behave as if O_TRUNC was supplied
    98    * Open modes O_APPEND, O_TRUNC are ignored
    99    * If an upload fails it can't be retried
   100  
   101  #### --vfs-cache-mode minimal
   102  
   103  This is very similar to "off" except that files opened for read AND
   104  write will be buffered to disks.  This means that files opened for
   105  write will be a lot more compatible, but uses the minimal disk space.
   106  
   107  These operations are not possible
   108  
   109    * Files opened for write only can't be seeked
   110    * Existing files opened for write must have O_TRUNC set
   111    * Files opened for write only will ignore O_APPEND, O_TRUNC
   112    * If an upload fails it can't be retried
   113  
   114  #### --vfs-cache-mode writes
   115  
   116  In this mode files opened for read only are still read directly from
   117  the remote, write only and read/write files are buffered to disk
   118  first.
   119  
   120  This mode should support all normal file system operations.
   121  
   122  If an upload fails it will be retried up to --low-level-retries times.
   123  
   124  #### --vfs-cache-mode full
   125  
   126  In this mode all reads and writes are buffered to and from disk.  When
   127  a file is opened for read it will be downloaded in its entirety first.
   128  
   129  This may be appropriate for your needs, or you may prefer to look at
   130  the cache backend which does a much more sophisticated job of caching,
   131  including caching directory hierarchies and chunks of files.
   132  
   133  In this mode, unlike the others, when a file is written to the disk,
   134  it will be kept on the disk after it is written to the remote.  It
   135  will be purged on a schedule according to ` + "`--vfs-cache-max-age`" + `.
   136  
   137  This mode should support all normal file system operations.
   138  
   139  If an upload or download fails it will be retried up to
   140  --low-level-retries times.
   141  
   142  ### Case Sensitivity
   143  
   144  Linux file systems are case-sensitive: two files can differ only
   145  by case, and the exact case must be used when opening a file.
   146  
   147  Windows is not like most other operating systems supported by rclone.
   148  File systems in modern Windows are case-insensitive but case-preserving:
   149  although existing files can be opened using any case, the exact case used
   150  to create the file is preserved and available for programs to query.
   151  It is not allowed for two files in the same directory to differ only by case.
   152  
   153  Usually file systems on macOS are case-insensitive. It is possible to make macOS
   154  file systems case-sensitive but that is not the default
   155  
   156  The "--vfs-case-insensitive" mount flag controls how rclone handles these
   157  two cases. If its value is "false", rclone passes file names to the mounted
   158  file system as is. If the flag is "true" (or appears without a value on
   159  command line), rclone may perform a "fixup" as explained below.
   160  
   161  The user may specify a file name to open/delete/rename/etc with a case
   162  different than what is stored on mounted file system. If an argument refers
   163  to an existing file with exactly the same name, then the case of the existing
   164  file on the disk will be used. However, if a file name with exactly the same
   165  name is not found but a name differing only by case exists, rclone will
   166  transparently fixup the name. This fixup happens only when an existing file
   167  is requested. Case sensitivity of file names created anew by rclone is
   168  controlled by an underlying mounted file system.
   169  
   170  Note that case sensitivity of the operating system running rclone (the target)
   171  may differ from case sensitivity of a file system mounted by rclone (the source).
   172  The flag controls whether "fixup" is performed to satisfy the target.
   173  
   174  If the flag is not provided on command line, then its default value depends
   175  on the operating system where rclone runs: "true" on Windows and macOS, "false"
   176  otherwise. If the flag is provided without a value, then it is "true".
   177  `