Ceph Filesystem ( CephFS) :: Step by Step Configuration

CephFS 

Ceph Filesystem is a posix compliant file system that uses ceph storage cluster to store its data. This is the only ceph component that is not ready for production , i would like to say ready for pre-production.


Internals 

Thanks to http://ceph.com/docs/master/cephfs/ for Image 

Requirement of CephFS

• You need a running ceph cluster with at least one MDS node. MDS is required for CephFS to work.
• If you don't have MDS configure one
• # ceph-deploy mds create <MDS-NODE-ADDRESS>

Note : If you are running short of hardware or want to save hardware you can run MDS services on existing Monitor nodes. MDS services does not need much resources

• A Ceph client to mount cephFS

Configuring CephFS

• Install ceph on client node

[root@storage0101-ib ceph]# ceph-deploy install na_fedora19
[ceph_deploy.cli][INFO  ] Invoked (1.3.2): /usr/bin/ceph-deploy install na_fedora19
[ceph_deploy.install][DEBUG ] Installing stable version emperor on cluster ceph hosts na_csc_fedora19
[ceph_deploy.install][DEBUG ] Detecting platform for host na_fedora19 ...
[na_csc_fedora19][DEBUG ] connected to host: na_csc_fedora19
[na_csc_fedora19][DEBUG ] detect platform information from remote host
[na_csc_fedora19][DEBUG ] detect machine type
[ceph_deploy.install][INFO  ] Distro info: Fedora 19 Schrödinger’s Cat
[na_csc_fedora19][INFO  ] installing ceph on na_fedora19
[na_csc_fedora19][INFO  ] Running command: rpm --import https://ceph.com/git/?p=ceph.git;a=blob_plain;f=keys/release.asc
[na_csc_fedora19][INFO  ] Running command: rpm -Uvh --replacepkgs --force --quiet http://ceph.com/rpm-emperor/fc19/noarch/ceph-release-1-0.fc19.noarch.rpm
[na_csc_fedora19][DEBUG ] ########################################
[na_csc_fedora19][DEBUG ] Updating / installing...
[na_csc_fedora19][DEBUG ] ########################################
[na_csc_fedora19][INFO  ] Running command: yum -y -q install ceph

[na_csc_fedora19][ERROR ] Warning: RPMDB altered outside of yum.
[na_csc_fedora19][DEBUG ] No Presto metadata available for Ceph
[na_csc_fedora19][INFO  ] Running command: ceph --version
[na_csc_fedora19][DEBUG ] ceph version 0.72.2 (a913ded2ff138aefb8cb84d347d72164099cfd60)
[root@storage0101-ib ceph]#

• Create a new pool for CephFS

# rados mkpool cephfs

• Create a new keyring (client.cephfs) for cephfs 

# ceph auth get-or-create client.cephfs mon 'allow r' osd 'allow rwx pool=cephfs' -o /etc/ceph/client.cephfs.keyring

• Extract secret key from keyring

# ceph-authtool -p -n client.cephfs /etc/ceph/client.cephfs.keyring > /etc/ceph/client.cephfs

• Copy the secret file to client node under /etc/ceph . This allow filesystem to mount when cephx authentication is enabled

# scp client.cephfs na_fedora19:/etc/ceph
client.cephfs                                                                100%   41     0.0KB/s   00:00

• List all the keys on ceph cluster

# ceph auth list                                               

Option-1 : Mount CephFS with Kernel Driver

• On the client machine add mount point in /etc/fstab . Provide IP address of your ceph monitor node and path of secret key that we have created above

192.168.200.101:6789:/ /cephfs ceph name=cephfs,secretfile=/etc/ceph/client.cephfs,noatime 0 2    

• Mount cephfs mount point  , you might see some "mount: error writing /etc/mtab: Invalid argument" but you can ignore them and check  df -h

[root@na_fedora19 ceph]# mount /cephfs
mount: error writing /etc/mtab: Invalid argument

[root@na_fedora19 ceph]#
[root@na_fedora19 ceph]# df -h
Filesystem              Size  Used Avail Use% Mounted on
/dev/vda1               7.8G  2.1G  5.4G  28% /
devtmpfs                3.9G     0  3.9G   0% /dev
tmpfs                   3.9G     0  3.9G   0% /dev/shm
tmpfs                   3.9G  288K  3.9G   1% /run
tmpfs                   3.9G     0  3.9G   0% /sys/fs/cgroup
tmpfs                   3.9G  2.6M  3.9G   1% /tmp
192.168.200.101:6789:/  419T  8.5T  411T   3% /cephfs
[root@na_fedora19 ceph]#

Option-2 : Mounting CephFS as FUSE

• Copy ceph configuration file ( ceph.conf ) from monitor node to client node and make sure it has permission of 644

# scp ceph.conf na_fedora19:/etc/ceph

# chmod 644 ceph.conf

• Copy the secret file from monitor node to client node under /etc/ceph. This allow filesystem to mount when cephx authentication is enabled ( we have done this earlier )

# scp client.cephfs na_fedora19:/etc/ceph
client.cephfs                                                                100%   41     0.0KB/s   00:00

• Make sure you have "ceph-fuse" package installed on client machine

# rpm -qa | grep -i ceph-fuse
ceph-fuse-0.72.2-0.fc19.x86_64 

• To mount Ceph Filesystem as FUSE use ceph-fuse comand 

[root@na_fedora19 ceph]# ceph-fuse -m 192.168.100.101:6789  /cephfs
ceph-fuse[3256]: starting ceph client
ceph-fuse[3256]: starting fuse
[root@na_csc_fedora19 ceph]#

[root@na_fedora19 ceph]# df -h
Filesystem      Size  Used Avail Use% Mounted on
/dev/vda1       7.8G  2.1G  5.4G  28% /
devtmpfs        3.9G     0  3.9G   0% /dev
tmpfs           3.9G     0  3.9G   0% /dev/shm
tmpfs           3.9G  292K  3.9G   1% /run
tmpfs           3.9G     0  3.9G   0% /sys/fs/cgroup
tmpfs           3.9G  2.6M  3.9G   1% /tmp
ceph-fuse       419T  8.5T  411T   3% /cephfs
[root@na_fedora19 ceph]#