Persistent Ceph Mount Point

Once you’ve got a Ceph cluster up and running you’re going to want to mount it somewhere. This guide assumes that the mount point will be on a machine that isn’t running Ceph, however if you’re mounting the storage on one of the Ceph server nodes then you can skip the package installation steps.

Install the Ceph Client

Before we start mounting anything, we’re going to need the required software installed. Assuming you’re on Debian run the below commands to add the key and the software repository for the Ceph binaries.

wget --no-check-certificate -q -O- 'https://git.ceph.com/git/?p=ceph.git;a=blob_plain;f=keys/release.asc' | apt-key add -
echo deb http://download.ceph.com/debian-firefly/ $(lsb_release -sc) main | tee /etc/apt/sources.list.d/ceph.list

Then run the apt-get commands to update your software index and install the Ceph binaries for the client.

apt-get update && apt-get install -y ceph-fs-common

Mount a Ceph device as a folder

Here we’re going to use /mnt/ha-pool as the mount point but you can change that to whatever you’d like. Run this command on any machine that you’d like to mount the Ceph volume on.

mkdir /mnt/ha-pool

Then we need to export the key so that the ceph-client can authenticate with the Ceph daemon. You could turn authentication off, or even create a non-admin user secret but for this tutorial we’ll just use the admin user. Run this command on your admin machine for your Ceph cluster (NOT on the client you’re setting up the mount point).

ceph-authtool --name client.admin /etc/ceph/ceph.client.admin.keyring --print-key

You’ll be presented with a string of letters and numbers. Copy this and add it to a file stored on your Ceph client machine. This is the ‘password’ or secret that the Ceph client will use to authenticate with the Ceph server. Paste the string into a file – you can store this anywhere but we’ll use /etc/ceph/admin.secret.

mkdir /etc/ceph/ 
vi /etc/ceph/admin.secret

Automatic mount

If you’d like the Ceph mount point to persist across client machine reboots then you’ll need to add an entry to /etc/fstab. Run the below command to add an entry to your fstab file so that the Ceph volume will be automatically mounted on machine start. This will mount the Ceph volume at /mnt/ha-pool and is referencing the Ceph monitor server nodes ceph1, ceph2 and ceph3 – make sure you change these values for your environment. You don’t have to specify more than one Ceph monitor server node, but it makes sense, just incase one of your nodes fails.

echo "cehp1,ceph2,ceph3:/ /mnt/ha-pool/ ceph name=admin,secretfile=/etc/ceph/admin.secret,noatime 0 2" >> /etc/fstab

Then to mount the volume, run the below mount command

mount /mnt/ha-pool

Manually mount filesystem

If you don’t need the mount to persist you can simply use the mount command. The parameters are very similar to the above section, with the Ceph monitor servers, secret file and mount point all specified. This will mount the Ceph volume at /mnt/ha-pool and is referencing the Ceph monitor server nodes ceph1, ceph2 and ceph3 – make sure you change these values for your environment.

mount -t ceph ceph1,ceph2,ceph3:/ /mnt/ha-pool -o name=admin,secretfile=/etc/ceph/admin.secret

Ceph mount ports and additional options

By default, and if left unspecified like the above examples, the Ceph client will use 6789 for your monitor server daemon. If you’ve specified a different port for your monitor daemon then you can specify them in the mount command. The same syntax can be used in your fstab.

mount -t ceph ceph1:1234,ceph2:4567,ceph3:8910/ /mnt/ha-pool -o name=admin,secretfile=/etc/ceph/admin.secret

You can also specify your secret key directly, rather than a file that contains it. I won’t go into the security implications of this here, but I’m sure you can imagine one or two. Again, the same syntax can be used in your fstab.

mount -t ceph ceph1,ceph2,ceph3:/ /mnt/ha-pool -o name=admin,secret=AQATSKdNGBnwLhAAnNDKnH65FmVKpXZJVasUeQ==