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mount.ceph - mount a ceph file system


mount.ceph [monaddr1,monaddr2,...]:/[subdir] dir [
-o options ]


mount.ceph is a helper for mounting the Ceph file system on a Linux host. It serves to resolve monitor hostname(s) into IP addresses and read authentication keys from disk; the Linux kernel client component does most of the real work. In fact, it is possible to mount a non-authenticated Ceph file system without mount.ceph by specifying monitor address(es) by IP:

mount -t ceph mountpoint

Each monitor address monaddr takes the form host[:port]. If the port is not specified, the Ceph default of 6789 is assumed.

Multiple monitor addresses can be separated by commas. Only one responsible monitor is needed to successfully mount; the client will learn about all monitors from any responsive monitor. However, it is a good idea to specify more than one in case one happens to be down at the time of mount.

If the host portion of the device is left blank, then mount.ceph will attempt to determine monitor addresses using local configuration files and/or DNS SRV records.

A subdirectory subdir may be specified if a subset of the file system is to be mounted.

Mount helper application conventions dictate that the first two options are device to be mounted and destination path. Options must be passed only after these fixed arguments.


int (bytes), max write size. Default: 16777216 (16*1024*1024) (writeback uses smaller of wsize and stripe unit)
int (bytes), max read size. Default: 16777216 (16*1024*1024)
int (bytes), max readahead. Default: 8388608 (8192*1024)
int (seconds), Default: 60
int, Default: 5
int (seconds), Default: 60
int (seconds), Default: 60
int, cap release delay, Default: 5
int, cap release delay, Default: 60
int, Default: calculated
int, Default: 1024
int, Default: 524288 (512*1024)
int (kb), max writeback in flight. scale with available memory. Default: calculated from available memory
string, set the name of the hidden snapdir. Default: .snap
RADOS user to authenticate as when using cephx. Default: guest
secret key for use with cephx. This option is insecure because it exposes the secret on the command line. To avoid this, use the secretfile option.
path to file containing the secret key to use with cephx
my ip
create a new client instance, instead of sharing an existing instance of a client mounting the same cluster
funky cat dirname for stats, Default: off
no funky cat dirname for stats
Report the recursive size of the directory contents for st_size on directories. Default: off
Do not report the recursive size of the directory contents for st_size on directories.
no data crc on writes
no dcache readdir
Path to a ceph.conf file. This is used to initialize the ceph context for autodiscovery of monitor addresses and auth secrets. The default is to use the standard search path for ceph.conf files.


If the secret and secretfile options are not specified on the command-line then the mount helper will spawn a child process that will use the standard ceph library routines to find a keyring and fetch the secret from it.


Mount the full file system:

mount.ceph monhost:/ /mnt/foo

If there are multiple monitors:

mount.ceph monhost1,monhost2,monhost3:/ /mnt/foo

If ceph-mon(8) is running on a non-standard port:

mount.ceph monhost1:7000,monhost2:7000,monhost3:7000:/ /mnt/foo

To automatically determine the monitor addresses from local configuration:

mount.ceph :/ /mnt/foo

To mount only part of the namespace:

mount.ceph monhost1:/some/small/thing /mnt/thing

Assuming mount.ceph(8) is installed properly, it should be automatically invoked by mount(8) like so:

mount -t ceph monhost:/ /mnt/foo


mount.ceph is part of Ceph, a massively scalable, open-source, distributed storage system. Please refer to the Ceph documentation at for more information.


ceph-fuse(8), ceph(8)


2010-2021, Inktank Storage, Inc. and contributors. Licensed under Creative Commons Attribution Share Alike 3.0 (CC-BY-SA-3.0)

May 27, 2021 dev