Introduction

This is part of the Distributed Storage series. We assume you have a Kubernetes cluster running as described in Kubernetes With Microk8s. Using the same virtual machines, we will deploy a Ceph cluster and enable different types of storage: file, object, and block (default).

Prerequisites

It is worth repeating that each VM has a disk which can be consumed by Ceph:

$ lsblk | grep -v loop
NAME                      MAJ:MIN RM   SIZE RO TYPE MOUNTPOINTS
sr0                        11:0    1   2.7G  0 rom  
nvme0n1                   259:0    0    80G  0 disk 
├─nvme0n1p1               259:1    0     1G  0 part /boot/efi
├─nvme0n1p2               259:2    0     2G  0 part /boot
└─nvme0n1p3               259:3    0  76.9G  0 part 
  └─ubuntu--vg-ubuntu--lv 252:0    0  38.5G  0 lvm  /
nvme0n2                   259:4    0    20G  0 disk

Bootstrap Ceph Cluster

Let us install microceph.

You can purge any existing installation, or restart installation in case something goes wrong later.

# This will remove any existing installaion
sudo snap remove microceph --purge

The following bootstraps a new cluster:

manas@manas-s01:~$ sudo snap install microceph --channel=stable
microceph (squid/stable) 19.2.0+snap3b53da1c21 from Canonical✓ installed
manas@manas-s01:~$ sudo microceph cluster bootstrap
manas@manas-s01:~$ sudo microceph status
MicroCeph deployment summary:
- manas-s01 (192.168.148.134)
  Services: mds, mgr, mon
  Disks: 0

We now have a single-node cluster. Adding other nodes is a bit different from microk8s. The cluster add command generates a unique token that includes the hostname. If the cluster join fails, ensure you have used the correct hostname. For example, the VMs in this demo have hostname manas-s01, manas-s02 and mans-s03. Naming things is hard.

# Generate token to add nodes
$ sudo microceph cluster add <hostname>
<token>
# For each node 
$ sudo microceph cluster join <token>
# Master Node
manas@manas-s01:~$ sudo microceph status
MicroCeph deployment summary:
- manas-s01 (192.168.148.135)
  Services: mds, mgr, mon
  Disks: 0
- manas-s02 (192.168.148.136)
  Services: mds, mgr, mon
  Disks: 0
- manas-s03 (192.168.148.137)
  Services: mds, mgr, mon
  Disks: 0

Next, we will claim storage to be consumed by the cluster. Remember, we kept an extra disk for this purpose. Repeat the following for each node:

# Repeat for each node 
manas@manas-s01:~$ sudo microceph disk add /dev/nvme0n2 --wipe

+--------------+---------+
|     PATH     | STATUS  |
+--------------+---------+
| /dev/nvme0n2 | Success |
+--------------+---------+

# Status shows that we have 3 OSDs
manas@manas-s01:~$ sudo microceph status 
MicroCeph deployment summary:
- manas-s01 (192.168.148.134)
  Services: mds, mgr, mon, osd
  Disks: 1
- manas-s02 (192.168.148.136)
  Services: mds, mgr, mon, osd
  Disks: 1
- manas-s03 (192.168.148.135)
  Services: mds, mgr, mon, osd
  Disks: 1

Check the cluster and disk status:

manas@manas-s01:~$ sudo microceph.ceph status 
  cluster:
    id:     e43d58a8-deb0-43d9-b7ef-d6159f114c02
    health: HEALTH_OK

  services:
    mon: 3 daemons, quorum manas-s01,manas-s02,manas-s03 (age 5m)
    mgr: manas-s01(active, since 52m), standbys: manas-s02, manas-s03
    osd: 3 osds: 3 up (since 101s), 3 in (since 108s)

  data:
    pools:   1 pools, 1 pgs
    objects: 2 objects, 577 KiB
    usage:   81 MiB used, 60 GiB / 60 GiB avail
    pgs:     1 active+clean

manas@manas-s01:~$ sudo microceph disk list
Disks configured in MicroCeph:
+-----+-----------+-----------------------------------------------------------+
| OSD | LOCATION  |                           PATH                            |
+-----+-----------+-----------------------------------------------------------+
| 1   | manas-s01 | /dev/disk/by-id/nvme-eui.3e9ca0d1c76f942a000c296b819ff947 |
+-----+-----------+-----------------------------------------------------------+
| 2   | manas-s02 | /dev/disk/by-id/nvme-eui.3e9ca0d1c76f942a000c296b819ff947 |
+-----+-----------+-----------------------------------------------------------+
| 3   | manas-s03 | /dev/disk/by-id/nvme-eui.3e9ca0d1c76f942a000c296b819ff947 |
+-----+-----------+-----------------------------------------------------------+

Now, to consume File and Object storage, we need to enable the relevant services.

For example, we enable rgw for object storage on all the nodes

$ sudo microceph enable rgw
$ sudo microceph status 
MicroCeph deployment summary:
- manas-s01 (192.168.148.134)
  Services: mds, mgr, mon, rgw, osd
  Disks: 1
- manas-s02 (192.168.148.136)
  Services: mds, mgr, mon, rgw, osd
  Disks: 1
- manas-s03 (192.168.148.135)
  Services: mds, mgr, mon, rgw, osd
  Disks: 1

Congratulations, your multi node Ceph cluster is ready!

Note that microceph commands are different from the ceph CLI

Reference docs for the Squid Release of Ceph:

• https://canonical-microceph.readthedocs-hosted.com/en/v19.2.0-squid/reference/

• https://docs.ceph.com/en/squid/man/8/ceph/