mount.ceph – mount a Ceph file system¶
Synopsis¶
Description¶
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 1.2.3.4:/ /mnt/mycephfs
The first argument is the device part of the mount command. It includes host’s socket and path within CephFS that will be mounted at the mount point. The socket, obviously, takes the form ip_address[:port]. If the port is not specified, the Ceph default of 6789 is assumed. Multiple monitor addresses can be passed by separating them by commas. Only one monitor is needed to mount successfully; the client will learn about all monitors from any responsive monitor. However, it is a good idea to specify more than one in case the 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. In similar way, if authentication is enabled on Ceph
cluster (which is done using CephX) and options secret and secretfile
are not specified in the command, 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.
A sub-directory of the file system can be mounted by specifying the (absolute) path to the sub-directory right after “:” after the socket in the device part of the mount command.
Mount helper application conventions dictate that the first two options are device to be mounted and the mountpoint for that device. Options must be passed only after these fixed arguments.
Options¶
Basic¶
- conf
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.
- command
mds_namespace=<fs-name> Specify the non-default file system to be mounted. Not passing this option mounts the default file system.
- mount_timeout
int (seconds), Default: 60
- name
RADOS user to authenticate as when using CephX. Default: guest
- secret
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.
- secretfile
path to file containing the secret key to use with CephX
- recover_session=<no|clean>
Set auto reconnect mode in the case where the client is blacklisted. The available modes are
noandclean. The default isno.no: never attempt to reconnect when client detects that it has beenblacklisted. Blacklisted clients will not attempt to reconnect and their operations will fail too.
clean: client reconnects to the Ceph cluster automatically when it detects that it has been blacklisted. During reconnect, client drops dirty data/metadata, invalidates page caches and writable file handles. After reconnect, file locks become stale because the MDS loses track of them. If an inode contains any stale file locks, read/write on the inode is not allowed until applications release all stale file locks.
Advanced¶
- cap_release_safety
int, Default: calculated
- caps_wanted_delay_max
int, cap release delay, Default: 60
- caps_wanted_delay_min
int, cap release delay, Default: 5
- dirstat
funky cat dirname for stats, Default: off
- nodirstat
no funky cat dirname for stats
- ip
my ip
- noasyncreaddir
no dcache readdir
- nocrc
no data crc on writes
- noshare
create a new client instance, instead of sharing an existing instance of a client mounting the same cluster
- osdkeepalive
int, Default: 5
- osdtimeout
int (seconds), Default: 60
- osd_idle_ttl
int (seconds), Default: 60
- rasize
int (bytes), max readahead. Default: 8388608 (8192*1024)
- rbytes
Report the recursive size of the directory contents for st_size on directories. Default: off
- norbytes
Do not report the recursive size of the directory contents for st_size on directories.
- readdir_max_bytes
int, Default: 524288 (512*1024)
- readdir_max_entries
int, Default: 1024
- rsize
int (bytes), max read size. Default: 16777216 (16*1024*1024)
- snapdirname
string, set the name of the hidden snapdir. Default: .snap
- write_congestion_kb
int (kb), max writeback in flight. scale with available memory. Default: calculated from available memory
- wsize
int (bytes), max write size. Default: 16777216 (16*1024*1024) (writeback uses smaller of wsize and stripe unit)
Examples¶
Mount the full file system:
mount.ceph :/ /mnt/mycephfs
Assuming mount.ceph is installed properly, it should be automatically invoked by mount(8):
mount -t ceph :/ /mnt/mycephfs
Mount only part of the namespace/file system:
mount.ceph :/some/directory/in/cephfs /mnt/mycephfs
Mount non-default FS, in case cluster has multiple FSs:
mount -t ceph :/ /mnt/mycephfs2 -o mds_namespace=mycephfs2
Pass the monitor host’s IP address, optionally:
mount.ceph 192.168.0.1:/ /mnt/mycephfs
Pass the port along with IP address if it’s running on a non-standard port:
mount.ceph 192.168.0.1:7000:/ /mnt/mycephfs
If there are multiple monitors, passes addresses separated by a comma:
mount.ceph 192.168.0.1,192.168.0.2,192.168.0.3:/ /mnt/mycephfs
If authentication is enabled on Ceph cluster:
mount.ceph :/ /mnt/mycephfs -o name=fs_username
Pass secret key for CephX user optionally:
mount.ceph :/ /mnt/mycephfs -o name=fs_username,secret=AQATSKdNGBnwLhAAnNDKnH65FmVKpXZJVasUeQ==
Pass file containing secret key to avoid leaving secret key in shell’s command history:
mount.ceph :/ /mnt/mycephfs -o name=fs_username,secretfile=/etc/ceph/fs_username.secret
Availability¶
mount.ceph is part of Ceph, a massively scalable, open-source, distributed storage system. Please refer to the Ceph documentation at http://ceph.com/docs for more information.
