rclone/rclone_mount.md at 57d5de6fba12832469c27ee4eae6c2d4aa6a988f

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date	title	slug	url
2019-06-20T16:09:42+01:00	rclone mount	rclone_mount	/commands/rclone_mount/

rclone mount

Mount the remote as file system on a mountpoint.

Synopsis

rclone mount allows Linux, FreeBSD, macOS and Windows to mount any of Rclone's cloud storage systems as a file system with FUSE.

First set up your remote using rclone config. Check it works with rclone ls etc.

Start the mount like this

rclone mount remote:path/to/files /path/to/local/mount

Or on Windows like this where X: is an unused drive letter

rclone mount remote:path/to/files X:

When the program ends, either via Ctrl+C or receiving a SIGINT or SIGTERM signal, the mount is automatically stopped.

The umount operation can fail, for example when the mountpoint is busy. When that happens, it is the user's responsibility to stop the mount manually with

# Linux
fusermount -u /path/to/local/mount
# OS X
umount /path/to/local/mount

Installing on Windows

To run rclone mount on Windows, you will need to download and install WinFsp.

WinFsp is an open source Windows File System Proxy which makes it easy to write user space file systems for Windows. It provides a FUSE emulation layer which rclone uses combination with cgofuse. Both of these packages are by Bill Zissimopoulos who was very helpful during the implementation of rclone mount for Windows.

Windows caveats

Note that drives created as Administrator are not visible by other accounts (including the account that was elevated as Administrator). So if you start a Windows drive from an Administrative Command Prompt and then try to access the same drive from Explorer (which does not run as Administrator), you will not be able to see the new drive.

The easiest way around this is to start the drive from a normal command prompt. It is also possible to start a drive from the SYSTEM account (using the WinFsp.Launcher infrastructure) which creates drives accessible for everyone on the system or alternatively using the nssm service manager.

Limitations

Without the use of "--vfs-cache-mode" this can only write files sequentially, it can only seek when reading. This means that many applications won't work with their files on an rclone mount without "--vfs-cache-mode writes" or "--vfs-cache-mode full". See the File Caching section for more info.

The bucket based remotes (eg Swift, S3, Google Compute Storage, B2, Hubic) won't work from the root - you will need to specify a bucket, or a path within the bucket. So swift: won't work whereas swift:bucket will as will swift:bucket/path. None of these support the concept of directories, so empty directories will have a tendency to disappear once they fall out of the directory cache.

Only supported on Linux, FreeBSD, OS X and Windows at the moment.

rclone mount vs rclone sync/copy

File systems expect things to be 100% reliable, whereas cloud storage systems are a long way from 100% reliable. The rclone sync/copy commands cope with this with lots of retries. However rclone mount can't use retries in the same way without making local copies of the uploads. Look at the file caching for solutions to make mount more reliable.

Attribute caching

You can use the flag --attr-timeout to set the time the kernel caches the attributes (size, modification time etc) for directory entries.

The default is "1s" which caches files just long enough to avoid too many callbacks to rclone from the kernel.

In theory 0s should be the correct value for filesystems which can change outside the control of the kernel. However this causes quite a few problems such as rclone using too much memory, rclone not serving files to samba and excessive time listing directories.

The kernel can cache the info about a file for the time given by "--attr-timeout". You may see corruption if the remote file changes length during this window. It will show up as either a truncated file or a file with garbage on the end. With "--attr-timeout 1s" this is very unlikely but not impossible. The higher you set "--attr-timeout" the more likely it is. The default setting of "1s" is the lowest setting which mitigates the problems above.

If you set it higher ('10s' or '1m' say) then the kernel will call back to rclone less often making it more efficient, however there is more chance of the corruption issue above.

If files don't change on the remote outside of the control of rclone then there is no chance of corruption.

This is the same as setting the attr_timeout option in mount.fuse.

Filters

Note that all the rclone filters can be used to select a subset of the files to be visible in the mount.

systemd

When running rclone mount as a systemd service, it is possible to use Type=notify. In this case the service will enter the started state after the mountpoint has been successfully set up. Units having the rclone mount service specified as a requirement will see all files and folders immediately in this mode.

chunked reading

--vfs-read-chunk-size will enable reading the source objects in parts. This can reduce the used download quota for some remotes by requesting only chunks from the remote that are actually read at the cost of an increased number of requests.

When --vfs-read-chunk-size-limit is also specified and greater than --vfs-read-chunk-size, the chunk size for each open file will get doubled for each chunk read, until the specified value is reached. A value of -1 will disable the limit and the chunk size will grow indefinitely.

With --vfs-read-chunk-size 100M and --vfs-read-chunk-size-limit 0 the following parts will be downloaded: 0-100M, 100M-200M, 200M-300M, 300M-400M and so on. When --vfs-read-chunk-size-limit 500M is specified, the result would be 0-100M, 100M-300M, 300M-700M, 700M-1200M, 1200M-1700M and so on.

Chunked reading will only work with --vfs-cache-mode < full, as the file will always be copied to the vfs cache before opening with --vfs-cache-mode full.

Directory Cache

Using the --dir-cache-time flag, you can set how long a directory should be considered up to date and not refreshed from the backend. Changes made locally in the mount may appear immediately or invalidate the cache. However, changes done on the remote will only be picked up once the cache expires.

Alternatively, you can send a SIGHUP signal to rclone for it to flush all directory caches, regardless of how old they are. Assuming only one rclone instance is running, you can reset the cache like this:

kill -SIGHUP $(pidof rclone)

If you configure rclone with a remote control then you can use rclone rc to flush the whole directory cache:

rclone rc vfs/forget

Or individual files or directories:

rclone rc vfs/forget file=path/to/file dir=path/to/dir

File Buffering

The --buffer-size flag determines the amount of memory, that will be used to buffer data in advance.

Each open file descriptor will try to keep the specified amount of data in memory at all times. The buffered data is bound to one file descriptor and won't be shared between multiple open file descriptors of the same file.

This flag is a upper limit for the used memory per file descriptor. The buffer will only use memory for data that is downloaded but not not yet read. If the buffer is empty, only a small amount of memory will be used. The maximum memory used by rclone for buffering can be up to --buffer-size * open files.

File Caching

These flags control the VFS file caching options. The VFS layer is used by rclone mount to make a cloud storage system work more like a normal file system.

You'll need to enable VFS caching if you want, for example, to read and write simultaneously to a file. See below for more details.

Note that the VFS cache works in addition to the cache backend and you may find that you need one or the other or both.

--cache-dir string                   Directory rclone will use for caching.
--vfs-cache-max-age duration         Max age of objects in the cache. (default 1h0m0s)
--vfs-cache-mode string              Cache mode off|minimal|writes|full (default "off")
--vfs-cache-poll-interval duration   Interval to poll the cache for stale objects. (default 1m0s)
--vfs-cache-max-size int             Max total size of objects in the cache. (default off)

If run with -vv rclone will print the location of the file cache. The files are stored in the user cache file area which is OS dependent but can be controlled with --cache-dir or setting the appropriate environment variable.

The cache has 4 different modes selected by --vfs-cache-mode. The higher the cache mode the more compatible rclone becomes at the cost of using disk space.

Note that files are written back to the remote only when they are closed so if rclone is quit or dies with open files then these won't get written back to the remote. However they will still be in the on disk cache.

If using --vfs-cache-max-size note that the cache may exceed this size for two reasons. Firstly because it is only checked every --vfs-cache-poll-interval. Secondly because open files cannot be evicted from the cache.

--vfs-cache-mode off

In this mode the cache will read directly from the remote and write directly to the remote without caching anything on disk.

This will mean some operations are not possible

Files can't be opened for both read AND write
Files opened for write can't be seeked
Existing files opened for write must have O_TRUNC set
Files open for read with O_TRUNC will be opened write only
Files open for write only will behave as if O_TRUNC was supplied
Open modes O_APPEND, O_TRUNC are ignored
If an upload fails it can't be retried

--vfs-cache-mode minimal

This is very similar to "off" except that files opened for read AND write will be buffered to disks. This means that files opened for write will be a lot more compatible, but uses the minimal disk space.

These operations are not possible

Files opened for write only can't be seeked
Existing files opened for write must have O_TRUNC set
Files opened for write only will ignore O_APPEND, O_TRUNC
If an upload fails it can't be retried

--vfs-cache-mode writes

In this mode files opened for read only are still read directly from the remote, write only and read/write files are buffered to disk first.

This mode should support all normal file system operations.

If an upload fails it will be retried up to --low-level-retries times.

--vfs-cache-mode full

In this mode all reads and writes are buffered to and from disk. When a file is opened for read it will be downloaded in its entirety first.

This may be appropriate for your needs, or you may prefer to look at the cache backend which does a much more sophisticated job of caching, including caching directory hierarchies and chunks of files.

In this mode, unlike the others, when a file is written to the disk, it will be kept on the disk after it is written to the remote. It will be purged on a schedule according to --vfs-cache-max-age.