We are running a three-node Ceph cluster on riboflavin, ginkgo and biloba for the purpose of cloud storage. Most Ceph services are running on riboflavin or ginkgo; biloba is just providing a tiny bit of extra storage space.
Official documentation: https://docs.ceph.com/en/latest/
At the time this page was written, the latest version of Ceph was 'Pacific'; check the website above to see what the latest version is.
The instructions below were adapted from https://docs.ceph.com/en/pacific/cephadm/install/.
riboflavin was used as the bootstrap host, since it has the most storage.
Add the following to /etc/apt/sources.list.d/ceph.list:
deb http://mirror.csclub.uwaterloo.ca/ceph/debian-pacific/ bullseye main
Download the Ceph release key for the Debian packages:
wget -O /etc/apt/trusted.gpg.d/ceph.release.gpg https://download.ceph.com/keys/release.gpg
apt update apt install cephadm podman ceph boostrap --mon-ip 172.19.168.25
For the rest of the instructions below, the
ceph command can be run inside a Podman container by running
cephadm shell. Alternatively, you can install the
ceph-common package to run
ceph directly on the host.
Add the disks for riboflavin:
ceph orch daemon add osd riboflavin:/dev/sdb ceph orch daemon add osd riboflavin:/dev/sdc
Note: Unfortunately Ceph didn't like it when I used one of the /dev/disk/by-id paths, so I had to use the /dev/sdX paths instead. I'm not sure what'll happen if the device names change at boot. Let's just cross our fingers and pray.
Add more hosts:
ceph orch host add ginkgo 172.19.168.22 --labels _admin ceph orch host add biloba 172.19.168.23
Add each available disk on each of the additional hosts.
Disable unnecessary services:
ceph orch rm alertmanager ceph orch rm grafana ceph orch rm node-exporter
Set the autoscale profile to scale-up instead of scale-down:
ceph osd pool set autoscale-profile scale-up
Set the default pool replication factor to 2 instead of 3:
ceph config set global osd_pool_default_size 2
Deploy the Managers and Monitors on riboflavin and ginkgo only:
ceph orch apply mon --placement '2 riboflavin ginkgo' ceph orch apply mgr --placement '2 riboflavin ginkgo'
CloudStack Primary Storage
We are using RBD (RADOS Block Device) for CloudStack primary storage. The instructions below were adapted from https://docs.ceph.com/en/pacific/rbd/rbd-cloudstack/.
Create and initialize a pool:
ceph osd pool create cloudstack rbd pool init cloudstack
Create a user for CloudStack:
ceph auth get-or-create client.cloudstack mon 'profile rbd' osd 'profile rbd pool=cloudstack'
Make a backup of this key. There is currently a copy in /etc/ceph/ceph.client.cloudstack.keyring on biloba. If you want to use the
ceph command with this set of credentials, use the
-n flag, e.g.
ceph -n client.cloudstack status
Here are some RBD commands which might be useful:
List images (i.e. block devices) in the cloudstack pool:
rbd ls -p cloudstack
View snapshots for an image:
rbd snap ls cloudstack/265dc008-4db5-11ec-b585-32ee6075b19b
Unprotect a snapshot:
rbd snap unprotect cloudstack/265dc008-4db5-11ec-b585-32ee6075b19b@cloudstack-base-snap
Purge all snapshots for an image (after unprotecting them):
rbd snap purge cloudstack/265dc008-4db5-11ec-b585-32ee6075b19b
Delete an image:
rbd rm cloudstack/265dc008-4db5-11ec-b585-32ee6075b19b
A quick 'n dirty script to delete all images in the pool:
rbd ls -p cloudstack | while read image; do rbd snap unprotect cloudstack/$image@cloudstack-base-snap; done rbd ls -p cloudstack | while read image; do rbd snap purge cloudstack/$image; done rbd ls -p cloudstack | while read image; do rbd rm cloudstack/$image; done
CloudStack Secondary Storage
We are using NFS (v4) for CloudStack secondary storage. The steps below were adapted from:
Create a new CephFS filesystem:
ceph fs volume create cloudstack-secondary
Enable the NFS module:
ceph mgr module enable nfs
Create a cluster placed on two hosts:
ceph nfs cluster create cloudstack-nfs --placement '2 riboflavin ginkgo'
View cluster info:
ceph nfs cluster ls ceph nfs cluster info cloudstack-nfs
Now create a CephFS export:
ceph nfs export create cephfs cloudstack-secondary cloudstack-nfs /cloudstack-secondary /
View export info:
ceph nfs export ls cloudstack-nfs ceph nfs export get cloudstack-nfs /cloudstack-secondary
Now on the clients, we can just mount the NFS export normally:
mkdir /mnt/cloudstack-secondary mount -t nfs4 -o port=2049 ceph-nfs.cloud.csclub.uwaterloo.ca:/cloudstack-secondary /mnt/cloudstack-secondary
The NFS module in Ceph is just NFS-Ganesha, which does theoretically support ACLs, but I wasn't able to get it to work. I kept on getting some weird Python error. So we're going to use our iptables-fu instead (on riboflavin and ginkgo; make sure iptables-persistent is installed):
iptables -N CEPH-NFS iptables -A INPUT -j CEPH-NFS iptables -A CEPH-NFS -s 172.19.168.0/27 -j RETURN iptables -A CEPH-NFS -p tcp --dport 2049 -j REJECT iptables -A CEPH-NFS -p udp --dport 2049 -j REJECT iptables-save > /etc/iptables/rules.v4 ip6tables -N CEPH-NFS ip6tables -A INPUT -j CEPH-NFS ip6tables -A CEPH-NFS -s fd74:6b6a:8eca:4902::/64 -j RETURN ip6tables -A CEPH-NFS -p tcp --dport 2049 -j REJECT ip6tables -A CEPH-NFS -p udp --dport 2049 -j REJECT ip6tables-save > /etc/iptables/rules.v6
There is a web dashboard for Ceph running on riboflavin which is useful to get a holistic view of the system. You will need to do a port-forward over SSH:
ssh -L 8443:172.19.168.25:8443 riboflavin
Now if you visit https://localhost:8443 (ignore the HTTPS warning), you can login to the dashboard. Credentials are stored in the usual place.
Removing a disk
Only do this if you are certain that a disk has failed. In the example below, osd.3 is the OSD with the bad disk.
ceph osd down osd.3 ceph osd out osd.3 ceph orch daemon rm osd.3 --force ceph osd destroy osd.3 --yes-i-really-mean-it ceph osd crush remove osd.3 ceph osd rm 3
Now on the host with the disk, run:
# view which LVM volumes are in which disks lsblk # get the device path of the bad Ceph LVM volume lvdisplay lvremove /dev/ceph-4318d615-2cde-4ea1-a25a-9cba09821fc3/osd-block-514bcfb1-07f2-4824-ba3c-c9031cc7d3e3 # get the VG with the bad LV vgdisplay vgremove 4318d615-2cde-4ea1-a25a-9cba09821fc3 # zero the beginning of the disk (if you plan on re-using it) dd if=/dev/zero of=/dev/sdc bs=1M count=10 conv=fsync
Here are some commands which may be useful. See the man page for a full reference.
ceph orch device ls
Note: this doesn't actually show all of the individual disks. I think it might have to do with the hardware RAID controllers.
Show OSDs (Object Storage Daemons) on the current host (this needs to be run from
ceph-volume lvm list
ceph orch ls
Show daemons of those services:
ceph orch ps
Show non-default config settings:
ceph config dump
ceph osd pool ls detail
ceph auth ls