---
title: "B2"
description: "Backblaze B2"
date: "2016-10-25"
---

<i class="fa fa-fire"></i>Backblaze B2
----------------------------------------

B2 is [Backblaze's cloud storage system](https://www.backblaze.com/b2/).

Paths are specified as `remote:bucket` (or `remote:` for the `lsd`
command.)  You may put subdirectories in too, eg `remote:bucket/path/to/dir`.

Here is an example of making a b2 configuration.  First run

    rclone config

This will guide you through an interactive setup process.  You will
need your account number (a short hex number) and key (a long hex
number) which you can get from the b2 control panel.

```
No remotes found - make a new one
n) New remote
q) Quit config
n/q> n
name> remote
Type of storage to configure.
Choose a number from below, or type in your own value
 1 / Amazon Drive
   \ "amazon cloud drive"
 2 / Amazon S3 (also Dreamhost, Ceph, Minio)
   \ "s3"
 3 / Backblaze B2
   \ "b2"
 4 / Dropbox
   \ "dropbox"
 5 / Encrypt/Decrypt a remote
   \ "crypt"
 6 / Google Cloud Storage (this is not Google Drive)
   \ "google cloud storage"
 7 / Google Drive
   \ "drive"
 8 / Hubic
   \ "hubic"
 9 / Local Disk
   \ "local"
10 / Microsoft OneDrive
   \ "onedrive"
11 / Openstack Swift (Rackspace Cloud Files, Memset Memstore, OVH)
   \ "swift"
12 / SSH/SFTP Connection
   \ "sftp"
13 / Yandex Disk
   \ "yandex"
Storage> 3
Account ID
account> 123456789abc
Application Key
key> 0123456789abcdef0123456789abcdef0123456789
Endpoint for the service - leave blank normally.
endpoint>
Remote config
--------------------
[remote]
account = 123456789abc
key = 0123456789abcdef0123456789abcdef0123456789
endpoint =
--------------------
y) Yes this is OK
e) Edit this remote
d) Delete this remote
y/e/d> y
```

This remote is called `remote` and can now be used like this

See all buckets

    rclone lsd remote:

Make a new bucket

    rclone mkdir remote:bucket

List the contents of a bucket

    rclone ls remote:bucket

Sync `/home/local/directory` to the remote bucket, deleting any
excess files in the bucket.

    rclone sync /home/local/directory remote:bucket

### --fast-list ###

This remote supports `--fast-list` which allows you to use fewer
transactions in exchange for more memory. See the [rclone
docs](/docs/#fast-list) for more details.

### Modified time ###

The modified time is stored as metadata on the object as
`X-Bz-Info-src_last_modified_millis` as milliseconds since 1970-01-01
in the Backblaze standard.  Other tools should be able to use this as
a modified time.

Modified times are used in syncing and are fully supported except in
the case of updating a modification time on an existing object.  In
this case the object will be uploaded again as B2 doesn't have an API
method to set the modification time independent of doing an upload.

### SHA1 checksums ###

The SHA1 checksums of the files are checked on upload and download and
will be used in the syncing process.

Large files (bigger than the limit in `--b2-upload-cutoff`) which are
uploaded in chunks will store their SHA1 on the object as
`X-Bz-Info-large_file_sha1` as recommended by Backblaze.

For a large file to be uploaded with an SHA1 checksum, the source
needs to support SHA1 checksums. The local disk supports SHA1
checksums so large file transfers from local disk will have an SHA1.
See [the overview](/overview/#features) for exactly which remotes
support SHA1.

Sources which don't support SHA1, in particular `crypt` will upload
large files without SHA1 checksums.  This may be fixed in the future
(see [#1767](https://github.com/ncw/rclone/issues/1767)).

Files sizes below `--b2-upload-cutoff` will always have an SHA1
regardless of the source.

### Transfers ###

Backblaze recommends that you do lots of transfers simultaneously for
maximum speed.  In tests from my SSD equipped laptop the optimum
setting is about `--transfers 32` though higher numbers may be used
for a slight speed improvement. The optimum number for you may vary
depending on your hardware, how big the files are, how much you want
to load your computer, etc.  The default of `--transfers 4` is
definitely too low for Backblaze B2 though.

Note that uploading big files (bigger than 200 MB by default) will use
a 96 MB RAM buffer by default.  There can be at most `--transfers` of
these in use at any moment, so this sets the upper limit on the memory
used.

### Versions ###

When rclone uploads a new version of a file it creates a [new version
of it](https://www.backblaze.com/b2/docs/file_versions.html).
Likewise when you delete a file, the old version will be marked hidden
and still be available.  Conversely, you may opt in to a "hard delete"
of files with the `--b2-hard-delete` flag which would permanently remove
the file instead of hiding it.

Old versions of files, where available, are visible using the 
`--b2-versions` flag.

If you wish to remove all the old versions then you can use the
`rclone cleanup remote:bucket` command which will delete all the old
versions of files, leaving the current ones intact.  You can also
supply a path and only old versions under that path will be deleted,
eg `rclone cleanup remote:bucket/path/to/stuff`.

When you `purge` a bucket, the current and the old versions will be
deleted then the bucket will be deleted.

However `delete` will cause the current versions of the files to
become hidden old versions.

Here is a session showing the listing and retrieval of an old
version followed by a `cleanup` of the old versions.

Show current version and all the versions with `--b2-versions` flag.

```
$ rclone -q ls b2:cleanup-test
        9 one.txt

$ rclone -q --b2-versions ls b2:cleanup-test
        9 one.txt
        8 one-v2016-07-04-141032-000.txt
       16 one-v2016-07-04-141003-000.txt
       15 one-v2016-07-02-155621-000.txt
```

Retrieve an old version

```
$ rclone -q --b2-versions copy b2:cleanup-test/one-v2016-07-04-141003-000.txt /tmp

$ ls -l /tmp/one-v2016-07-04-141003-000.txt
-rw-rw-r-- 1 ncw ncw 16 Jul  2 17:46 /tmp/one-v2016-07-04-141003-000.txt
```

Clean up all the old versions and show that they've gone.

```
$ rclone -q cleanup b2:cleanup-test

$ rclone -q ls b2:cleanup-test
        9 one.txt

$ rclone -q --b2-versions ls b2:cleanup-test
        9 one.txt
```

### Data usage ###

It is useful to know how many requests are sent to the server in different scenarios.

All copy commands send the following 4 requests:

```
/b2api/v1/b2_authorize_account
/b2api/v1/b2_create_bucket
/b2api/v1/b2_list_buckets
/b2api/v1/b2_list_file_names
```

The `b2_list_file_names` request will be sent once for every 1k files
in the remote path, providing the checksum and modification time of
the listed files. As of version 1.33 issue
[#818](https://github.com/ncw/rclone/issues/818) causes extra requests
to be sent when using B2 with Crypt. When a copy operation does not
require any files to be uploaded, no more requests will be sent.

Uploading files that do not require chunking, will send 2 requests per
file upload:

```
/b2api/v1/b2_get_upload_url
/b2api/v1/b2_upload_file/
```

Uploading files requiring chunking, will send 2 requests (one each to
start and finish the upload) and another 2 requests for each chunk:

```
/b2api/v1/b2_start_large_file
/b2api/v1/b2_get_upload_part_url
/b2api/v1/b2_upload_part/
/b2api/v1/b2_finish_large_file
```

### Specific options ###

Here are the command line options specific to this cloud storage
system.

#### --b2-chunk-size valuee=SIZE ####

When uploading large files chunk the file into this size.  Note that
these chunks are buffered in memory and there might a maximum of
`--transfers` chunks in progress at once.  5,000,000 Bytes is the
minimim size (default 96M).

#### --b2-upload-cutoff=SIZE ####

Cutoff for switching to chunked upload (default 190.735 MiB == 200
MB). Files above this size will be uploaded in chunks of
`--b2-chunk-size`.

This value should be set no larger than 4.657GiB (== 5GB) as this is
the largest file size that can be uploaded.


#### --b2-test-mode=FLAG ####

This is for debugging purposes only.

Setting FLAG to one of the strings below will cause b2 to return
specific errors for debugging purposes.

  * `fail_some_uploads`
  * `expire_some_account_authorization_tokens`
  * `force_cap_exceeded`

These will be set in the `X-Bz-Test-Mode` header which is documented
in the [b2 integrations
checklist](https://www.backblaze.com/b2/docs/integration_checklist.html).

#### --b2-versions ####

When set rclone will show and act on older versions of files.  For example

Listing without `--b2-versions`

```
$ rclone -q ls b2:cleanup-test
        9 one.txt
```

And with

```
$ rclone -q --b2-versions ls b2:cleanup-test
        9 one.txt
        8 one-v2016-07-04-141032-000.txt
       16 one-v2016-07-04-141003-000.txt
       15 one-v2016-07-02-155621-000.txt
```

Showing that the current version is unchanged but older versions can
be seen.  These have the UTC date that they were uploaded to the
server to the nearest millisecond appended to them.

Note that when using `--b2-versions` no file write operations are
permitted, so you can't upload files or delete them.
