rclone/docs/content/overview.md

title	description	type	date
Overview of cloud storage systems	Overview of cloud storage systems	page	2019-02-25

Overview of cloud storage systems

Each cloud storage system is slightly different. Rclone attempts to
provide a unified interface to them, but some underlying differences
show through.

Features

Here is an overview of the major features of each cloud storage system.

Name	Hash	ModTime	Case Insensitive	Duplicate Files	MIME Type
1Fichier	Whirlpool	No	No	Yes	R
Amazon Drive	MD5	No	Yes	No	R
Amazon S3	MD5	Yes	No	No	R/W
Backblaze B2	SHA1	Yes	No	No	R/W
Box	SHA1	Yes	Yes	No	-
Citrix ShareFile	MD5	Yes	Yes	No	-
Dropbox	DBHASH †	Yes	Yes	No	-
FTP	-	No	No	No	-
Google Cloud Storage	MD5	Yes	No	No	R/W
Google Drive	MD5	Yes	No	Yes	R/W
Google Photos	-	No	No	Yes	R
HTTP	-	No	No	No	R
Hubic	MD5	Yes	No	No	R/W
Jottacloud	MD5	Yes	Yes	No	R/W
Koofr	MD5	No	Yes	No	-
Mail.ru Cloud	Mailru ‡‡‡	Yes	Yes	No	-
Mega	-	No	No	Yes	-
Memory	MD5	Yes	No	No	-
Microsoft Azure Blob Storage	MD5	Yes	No	No	R/W
Microsoft OneDrive	SHA1 ‡‡	Yes	Yes	No	R
OpenDrive	MD5	Yes	Yes	No	-
Openstack Swift	MD5	Yes	No	No	R/W
pCloud	MD5, SHA1	Yes	No	No	W
premiumize.me	-	No	Yes	No	R
put.io	CRC-32	Yes	No	Yes	R
QingStor	MD5	No	No	No	R/W
SFTP	MD5, SHA1 ‡	Yes	Depends	No	-
SugarSync	-	No	No	No	-
WebDAV	MD5, SHA1 ††	Yes †††	Depends	No	-
Yandex Disk	MD5	Yes	No	No	R/W
The local filesystem	All	Yes	Depends	No	-

Hash

The cloud storage system supports various hash types of the objects.
The hashes are used when transferring data as an integrity check and
can be specifically used with the --checksum flag in syncs and in
the check command.

To use the verify checksums when transferring between cloud storage
systems they must support a common hash type.

† Note that Dropbox supports its own custom
hash.
This is an SHA256 sum of all the 4MB block SHA256s.

‡ SFTP supports checksums if the same login has shell access and md5sum
or sha1sum as well as echo are in the remote's PATH.

†† WebDAV supports hashes when used with Owncloud and Nextcloud only.

††† WebDAV supports modtimes when used with Owncloud and Nextcloud only.

‡‡ Microsoft OneDrive Personal supports SHA1 hashes, whereas OneDrive
for business and SharePoint server support Microsoft's own
QuickXorHash.

‡‡‡ Mail.ru uses its own modified SHA1 hash

ModTime

The cloud storage system supports setting modification times on
objects. If it does then this enables a using the modification times
as part of the sync. If not then only the size will be checked by
default, though the MD5SUM can be checked with the --checksum flag.

All cloud storage systems support some kind of date on the object and
these will be set when transferring from the cloud storage system.

Case Insensitive

If a cloud storage systems is case sensitive then it is possible to
have two files which differ only in case, eg file.txt and
FILE.txt. If a cloud storage system is case insensitive then that
isn't possible.

This can cause problems when syncing between a case insensitive
system and a case sensitive system. The symptom of this is that no
matter how many times you run the sync it never completes fully.

The local filesystem and SFTP may or may not be case sensitive
depending on OS.

• Windows - usually case insensitive, though case is preserved
• OSX - usually case insensitive, though it is possible to format case sensitive
• Linux - usually case sensitive, but there are case insensitive file systems (eg FAT formatted USB keys)

Most of the time this doesn't cause any problems as people tend to
avoid files whose name differs only by case even on case sensitive
systems.

Duplicate files

If a cloud storage system allows duplicate files then it can have two
objects with the same name.

This confuses rclone greatly when syncing - use the rclone dedupe
command to rename or remove duplicates.

Restricted filenames

Some cloud storage systems might have restrictions on the characters
that are usable in file or directory names.
When rclone detects such a name during a file upload, it will
transparently replace the restricted characters with similar looking
Unicode characters.

This process is designed to avoid ambiguous file names as much as
possible and allow to move files between many cloud storage systems
transparently.

The name shown by rclone to the user or during log output will only
contain a minimal set of replaced characters
to ensure correct formatting and not necessarily the actual name used
on the cloud storage.

This transformation is reversed when downloading a file or parsing
rclone arguments.
For example, when uploading a file named my file?.txt to Onedrive
will be displayed as my file?.txt on the console, but stored as
my file？.txt (the ? gets replaced by the similar looking ？
character) to Onedrive.
The reverse transformation allows to read a fileunusual/name.txt
from Google Drive, by passing the name unusual／name.txt (the / needs
to be replaced by the similar looking ／ character) on the command line.

Default restricted characters

The table below shows the characters that are replaced by default.

When a replacement character is found in a filename, this character
will be escaped with the ‛ character to avoid ambiguous file names.
(e.g. a file named ␀.txt would shown as ‛␀.txt)

Each cloud storage backend can use a different set of characters,
which will be specified in the documentation for each backend.

Character	Value	Replacement
NUL	0x00	␀
SOH	0x01	␁
STX	0x02	␂
ETX	0x03	␃
EOT	0x04	␄
ENQ	0x05	␅
ACK	0x06	␆
BEL	0x07	␇
BS	0x08	␈
HT	0x09	␉
LF	0x0A	␊
VT	0x0B	␋
FF	0x0C	␌
CR	0x0D	␍
SO	0x0E	␎
SI	0x0F	␏
DLE	0x10	␐
DC1	0x11	␑
DC2	0x12	␒
DC3	0x13	␓
DC4	0x14	␔
NAK	0x15	␕
SYN	0x16	␖
ETB	0x17	␗
CAN	0x18	␘
EM	0x19	␙
SUB	0x1A	␚
ESC	0x1B	␛
FS	0x1C	␜
GS	0x1D	␝
RS	0x1E	␞
US	0x1F	␟
/	0x2F	／
DEL	0x7F	␡

The default encoding will also encode these file names as they are
problematic with many cloud storage systems.

File name	Replacement
.	．
..	．．

Invalid UTF-8 bytes

Some backends only support a sequence of well formed UTF-8 bytes
as file or directory names.

In this case all invalid UTF-8 bytes will be replaced with a quoted
representation of the byte value to allow uploading a file to such a
backend. For example, the invalid byte 0xFE will be encoded as ‛FE.

A common source of invalid UTF-8 bytes are local filesystems, that store
names in a different encoding than UTF-8 or UTF-16, like latin1. See the
local filenames section for details.

Encoding option

Most backends have an encoding options, specified as a flag
--backend-encoding where backend is the name of the backend, or as
a config parameter encoding (you'll need to select the Advanced
config in rclone config to see it).

This will have default value which encodes and decodes characters in
such a way as to preserve the maximum number of characters (see
above).

However this can be incorrect in some scenarios, for example if you
have a Windows file system with characters such as ＊ and ？ that
you want to remain as those characters on the remote rather than being
translated to * and ?.

The --backend-encoding flags allow you to change that. You can
disable the encoding completely with --backend-encoding None or set
encoding = None in the config file.

Encoding takes a comma separated list of encodings. You can see the
list of all available characters by passing an invalid value to this
flag, eg --local-encoding "help" and rclone help flags encoding
will show you the defaults for the backends.

Encoding	Characters
Asterisk	*
BackQuote	`
BackSlash	\
Colon	:
CrLf	CR 0x0D, LF 0x0A
Ctl	All control characters 0x00-0x1F
Del	DEL 0x7F
Dollar	$
Dot	.
DoubleQuote	"
Hash	#
InvalidUtf8	An invalid UTF-8 character (eg latin1)
LeftCrLfHtVt	CR 0x0D, LF 0x0A,HT 0x09, VT 0x0B on the left of a string
LeftPeriod	. on the left of a string
LeftSpace	SPACE on the left of a string
LeftTilde	~ on the left of a string
LtGt	<, >
None	No characters are encoded
Percent	%
Pipe	|
Question	?
RightCrLfHtVt	CR 0x0D, LF 0x0A, HT 0x09, VT 0x0B on the right of a string
RightPeriod	. on the right of a string
RightSpace	SPACE on the right of a string
SingleQuote	'
Slash	/

To take a specific example, the FTP backend's default encoding is

--ftp-encoding "Slash,Del,Ctl,RightSpace,Dot"

However, let's say the FTP server is running on Windows and can't have
any of the invalid Windows characters in file names. You are backing
up Linux servers to this FTP server which do have those characters in
file names. So you would add the Windows set which are

Slash,LtGt,DoubleQuote,Colon,Question,Asterisk,Pipe,BackSlash,Ctl,RightSpace,RightPeriod,InvalidUtf8,Dot

to the existing ones, giving:

Slash,LtGt,DoubleQuote,Colon,Question,Asterisk,Pipe,BackSlash,Ctl,RightSpace,RightPeriod,InvalidUtf8,Dot,Del,RightSpace

This can be specified using the --ftp-encoding flag or using an encoding parameter in the config file.

Or let's say you have a Windows server but you want to preserve ＊
and ？, you would then have this as the encoding (the Windows
encoding minus Asterisk and Question).

Slash,LtGt,DoubleQuote,Colon,Pipe,BackSlash,Ctl,RightSpace,RightPeriod,InvalidUtf8,Dot

This can be specified using the --local-encoding flag or using an
encoding parameter in the config file.

MIME Type

MIME types (also known as media types) classify types of documents
using a simple text classification, eg text/html or
application/pdf.

Some cloud storage systems support reading (R) the MIME type of
objects and some support writing (W) the MIME type of objects.

The MIME type can be important if you are serving files directly to
HTTP from the storage system.

If you are copying from a remote which supports reading (R) to a
remote which supports writing (W) then rclone will preserve the MIME
types. Otherwise they will be guessed from the extension, or the
remote itself may assign the MIME type.

Optional Features

All the remotes support a basic set of features, but there are some
optional features supported by some remotes used to make some
operations more efficient.

Name	Purge	Copy	Move	DirMove	CleanUp	ListR	StreamUpload	LinkSharing	About	EmptyDir
1Fichier	No	No	No	No	No	No	No	No	No	Yes
Amazon Drive	Yes	No	Yes	Yes	No #575	No	No	No #2178	No	Yes
Amazon S3	No	Yes	No	No	No	Yes	Yes	No #2178	No	No
Backblaze B2	No	Yes	No	No	Yes	Yes	Yes	Yes	No	No
Box	Yes	Yes	Yes	Yes	No #575	No	Yes	Yes	No	Yes
Citrix ShareFile	Yes	Yes	Yes	Yes	No	No	Yes	No	No	Yes
Dropbox	Yes	Yes	Yes	Yes	No #575	No	Yes	Yes	Yes	Yes
FTP	No	No	Yes	Yes	No	No	Yes	No #2178	No	Yes
Google Cloud Storage	Yes	Yes	No	No	No	Yes	Yes	No #2178	No	No
Google Drive	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Google Photos	No	No	No	No	No	No	No	No	No	No
HTTP	No	No	No	No	No	No	No	No #2178	No	Yes
Hubic	Yes †	Yes	No	No	No	Yes	Yes	No #2178	Yes	No
Jottacloud	Yes	Yes	Yes	Yes	No	Yes	No	Yes	Yes	Yes
Mail.ru Cloud	Yes	Yes	Yes	Yes	Yes	No	No	Yes	Yes	Yes
Mega	Yes	No	Yes	Yes	Yes	No	No	No #2178	Yes	Yes
Memory	No	Yes	No	No	No	Yes	Yes	No	No	No
Microsoft Azure Blob Storage	Yes	Yes	No	No	No	Yes	No	No #2178	No	No
Microsoft OneDrive	Yes	Yes	Yes	Yes	No #575	No	No	Yes	Yes	Yes
OpenDrive	Yes	Yes	Yes	Yes	No	No	No	No	No	Yes
Openstack Swift	Yes †	Yes	No	No	No	Yes	Yes	No #2178	Yes	No
pCloud	Yes	Yes	Yes	Yes	Yes	No	No	No #2178	Yes	Yes
premiumize.me	Yes	No	Yes	Yes	No	No	No	Yes	Yes	Yes
put.io	Yes	No	Yes	Yes	Yes	No	Yes	No #2178	Yes	Yes
QingStor	No	Yes	No	No	Yes	Yes	No	No #2178	No	No
SFTP	No	No	Yes	Yes	No	No	Yes	No #2178	Yes	Yes
SugarSync	Yes	Yes	Yes	Yes	No	No	Yes	Yes	No	Yes
WebDAV	Yes	Yes	Yes	Yes	No	No	Yes ‡	No #2178	Yes	Yes
Yandex Disk	Yes	Yes	Yes	Yes	Yes	No	Yes	Yes	Yes	Yes
The local filesystem	Yes	No	Yes	Yes	No	No	Yes	No	Yes	Yes

Purge

This deletes a directory quicker than just deleting all the files in
the directory.

† Note Swift and Hubic implement this in order to delete directory
markers but they don't actually have a quicker way of deleting files
other than deleting them individually.

‡ StreamUpload is not supported with Nextcloud

Copy

Used when copying an object to and from the same remote. This known
as a server side copy so you can copy a file without downloading it
and uploading it again. It is used if you use rclone copy or
rclone move if the remote doesn't support Move directly.

If the server doesn't support Copy directly then for copy operations
the file is downloaded then re-uploaded.

Move

Used when moving/renaming an object on the same remote. This is known
as a server side move of a file. This is used in rclone move if the
server doesn't support DirMove.

If the server isn't capable of Move then rclone simulates it with
Copy then delete. If the server doesn't support Copy then rclone
will download the file and re-upload it.

DirMove

This is used to implement rclone move to move a directory if
possible. If it isn't then it will use Move on each file (which
falls back to Copy then download and upload - see Move section).

CleanUp

This is used for emptying the trash for a remote by rclone cleanup.

If the server can't do CleanUp then rclone cleanup will return an
error.

ListR

The remote supports a recursive list to list all the contents beneath
a directory quickly. This enables the --fast-list flag to work.
See the rclone docs for more details.

StreamUpload

Some remotes allow files to be uploaded without knowing the file size
in advance. This allows certain operations to work without spooling the
file to local disk first, e.g. rclone rcat.

LinkSharing

Sets the necessary permissions on a file or folder and prints a link
that allows others to access them, even if they don't have an account
on the particular cloud provider.

About

This is used to fetch quota information from the remote, like bytes
used/free/quota and bytes used in the trash.

This is also used to return the space used, available for rclone mount.

If the server can't do About then rclone about will return an
error.

EmptyDir

The remote supports empty directories. See Limitations
for details. Most Object/Bucket based remotes do not support this.