:pve-toplevel:
endif::manvolnum[]
-[thumbnail="gui-ceph-status.png"]
+[thumbnail="screenshot/gui-ceph-status.png"]
{pve} unifies your compute and storage systems, i.e. you can use the same
physical nodes within a cluster for both computing (processing VMs and
To simplify management, we provide 'pveceph' - a tool to install and
manage {ceph} services on {pve} nodes.
-.Ceph consists of a couple of Daemons footnote:[Ceph intro http://docs.ceph.com/docs/master/start/intro/], for use as a RBD storage:
+.Ceph consists of a couple of Daemons footnote:[Ceph intro http://docs.ceph.com/docs/luminous/start/intro/], for use as a RBD storage:
- Ceph Monitor (ceph-mon)
- Ceph Manager (ceph-mgr)
- Ceph OSD (ceph-osd; Object Storage Daemon)
-TIP: We recommend to get familiar with the Ceph vocabulary.
-footnote:[Ceph glossary http://docs.ceph.com/docs/luminous/glossary]
+TIP: We highly recommend to get familiar with Ceph's architecture
+footnote:[Ceph architecture http://docs.ceph.com/docs/luminous/architecture/]
+and vocabulary
+footnote:[Ceph glossary http://docs.ceph.com/docs/luminous/glossary].
Precondition
------------
-To build a Proxmox Ceph Cluster there should be at least three (preferably)
-identical servers for the setup.
-
-A 10Gb network, exclusively used for Ceph, is recommended. A meshed network
-setup is also an option if there are no 10Gb switches available, see our wiki
-article footnote:[Full Mesh Network for Ceph {webwiki-url}Full_Mesh_Network_for_Ceph_Server] .
+To build a hyper-converged Proxmox + Ceph Cluster there should be at least
+three (preferably) identical servers for the setup.
Check also the recommendations from
http://docs.ceph.com/docs/luminous/start/hardware-recommendations/[Ceph's website].
+.CPU
+Higher CPU core frequency reduce latency and should be preferred. As a simple
+rule of thumb, you should assign a CPU core (or thread) to each Ceph service to
+provide enough resources for stable and durable Ceph performance.
+
+.Memory
+Especially in a hyper-converged setup, the memory consumption needs to be
+carefully monitored. In addition to the intended workload from virtual machines
+and container, Ceph needs enough memory available to provide good and stable
+performance. As a rule of thumb, for roughly 1 TiB of data, 1 GiB of memory
+will be used by an OSD. OSD caching will use additional memory.
+
+.Network
+We recommend a network bandwidth of at least 10 GbE or more, which is used
+exclusively for Ceph. A meshed network setup
+footnote:[Full Mesh Network for Ceph {webwiki-url}Full_Mesh_Network_for_Ceph_Server]
+is also an option if there are no 10 GbE switches available.
+
+The volume of traffic, especially during recovery, will interfere with other
+services on the same network and may even break the {pve} cluster stack.
+
+Further, estimate your bandwidth needs. While one HDD might not saturate a 1 Gb
+link, multiple HDD OSDs per node can, and modern NVMe SSDs will even saturate
+10 Gbps of bandwidth quickly. Deploying a network capable of even more bandwith
+will ensure that it isn't your bottleneck and won't be anytime soon, 25, 40 or
+even 100 GBps are possible.
+
+.Disks
+When planning the size of your Ceph cluster, it is important to take the
+recovery time into consideration. Especially with small clusters, the recovery
+might take long. It is recommended that you use SSDs instead of HDDs in small
+setups to reduce recovery time, minimizing the likelihood of a subsequent
+failure event during recovery.
+
+In general SSDs will provide more IOPs than spinning disks. This fact and the
+higher cost may make a xref:pve_ceph_device_classes[class based] separation of
+pools appealing. Another possibility to speedup OSDs is to use a faster disk
+as journal or DB/**W**rite-**A**head-**L**og device, see
+xref:pve_ceph_osds[creating Ceph OSDs]. If a faster disk is used for multiple
+OSDs, a proper balance between OSD and WAL / DB (or journal) disk must be
+selected, otherwise the faster disk becomes the bottleneck for all linked OSDs.
+
+Aside from the disk type, Ceph best performs with an even sized and distributed
+amount of disks per node. For example, 4 x 500 GB disks with in each node is
+better than a mixed setup with a single 1 TB and three 250 GB disk.
+
+One also need to balance OSD count and single OSD capacity. More capacity
+allows to increase storage density, but it also means that a single OSD
+failure forces ceph to recover more data at once.
+
.Avoid RAID
As Ceph handles data object redundancy and multiple parallel writes to disks
-(OSDs) on its own, using a RAID controller normally doesn’t improves
+(OSDs) on its own, using a RAID controller normally doesn’t improve
performance or availability. On the contrary, Ceph is designed to handle whole
disks on it's own, without any abstraction in between. RAID controller are not
designed for the Ceph use case and may complicate things and sometimes even
WARNING: Avoid RAID controller, use host bus adapter (HBA) instead.
+NOTE: Above recommendations should be seen as a rough guidance for choosing
+hardware. Therefore, it is still essential to adapt it to your specific needs,
+test your setup and monitor health and performance continuously.
+
+[[pve_ceph_install_wizard]]
+Initial Ceph installation & configuration
+-----------------------------------------
+
+[thumbnail="screenshot/gui-node-ceph-install.png"]
+
+With {pve} you have the benefit of an easy to use installation wizard
+for Ceph. Click on one of your cluster nodes and navigate to the Ceph
+section in the menu tree. If Ceph is not already installed you will be
+offered to do so now.
+
+The wizard is divided into different sections, where each needs to be
+finished successfully in order to use Ceph. After starting the installation
+the wizard will download and install all required packages from {pve}'s ceph
+repository.
+
+After finishing the first step, you will need to create a configuration.
+This step is only needed once per cluster, as this configuration is distributed
+automatically to all remaining cluster members through {pve}'s clustered
+xref:chapter_pmxcfs[configuration file system (pmxcfs)].
+
+The configuration step includes the following settings:
+
+* *Public Network:* You should setup a dedicated network for Ceph, this
+setting is required. Separating your Ceph traffic is highly recommended,
+because it could lead to troubles with other latency dependent services,
+e.g., cluster communication may decrease Ceph's performance, if not done.
+
+[thumbnail="screenshot/gui-node-ceph-install-wizard-step2.png"]
+
+* *Cluster Network:* As an optional step you can go even further and
+separate the xref:pve_ceph_osds[OSD] replication & heartbeat traffic
+as well. This will relieve the public network and could lead to
+significant performance improvements especially in big clusters.
+You have two more options which are considered advanced and therefore
+should only changed if you are an expert.
+
+* *Number of replicas*: Defines the how often a object is replicated
+* *Minimum replicas*: Defines the minimum number of required replicas
+ for I/O to be marked as complete.
+
+Additionally you need to choose your first monitor node, this is required.
+
+That's it, you should see a success page as the last step with further
+instructions on how to go on. You are now prepared to start using Ceph,
+even though you will need to create additional xref:pve_ceph_monitors[monitors],
+create some xref:pve_ceph_osds[OSDs] and at least one xref:pve_ceph_pools[pool].
+
+The rest of this chapter will guide you on how to get the most out of
+your {pve} based Ceph setup, this will include aforementioned and
+more like xref:pveceph_fs[CephFS] which is a very handy addition to your
+new Ceph cluster.
+
+[[pve_ceph_install]]
Installation of Ceph Packages
-----------------------------
-
-On each node run the installation script as follows:
+Use {pve} Ceph installation wizard (recommended) or run the following
+command on each node:
[source,bash]
----
Creating initial Ceph configuration
-----------------------------------
-[thumbnail="gui-ceph-config.png"]
+[thumbnail="screenshot/gui-ceph-config.png"]
-After installation of packages, you need to create an initial Ceph
-configuration on just one node, based on your network (`10.10.10.0/24`
-in the following example) dedicated for Ceph:
+Use the {pve} Ceph installation wizard (recommended) or run the
+following command on one node:
[source,bash]
----
pveceph init --network 10.10.10.0/24
----
-This creates an initial configuration at `/etc/pve/ceph.conf`. That file is
-automatically distributed to all {pve} nodes by using
-xref:chapter_pmxcfs[pmxcfs]. The command also creates a symbolic link
-from `/etc/ceph/ceph.conf` pointing to that file. So you can simply run
-Ceph commands without the need to specify a configuration file.
+This creates an initial configuration at `/etc/pve/ceph.conf` with a
+dedicated network for ceph. That file is automatically distributed to
+all {pve} nodes by using xref:chapter_pmxcfs[pmxcfs]. The command also
+creates a symbolic link from `/etc/ceph/ceph.conf` pointing to that file.
+So you can simply run Ceph commands without the need to specify a
+configuration file.
[[pve_ceph_monitors]]
Creating Ceph Monitors
----------------------
-[thumbnail="gui-ceph-monitor.png"]
+[thumbnail="screenshot/gui-ceph-monitor.png"]
The Ceph Monitor (MON)
footnote:[Ceph Monitor http://docs.ceph.com/docs/luminous/start/intro/]
maintains a master copy of the cluster map. For high availability you need to
-have at least 3 monitors.
+have at least 3 monitors. One monitor will already be installed if you
+used the installation wizard. You wont need more than 3 monitors as long
+as your cluster is small to midsize, only really large clusters will
+need more than that.
On each node where you want to place a monitor (three monitors are recommended),
create it by using the 'Ceph -> Monitor' tab in the GUI or run.
Creating Ceph OSDs
------------------
-[thumbnail="gui-ceph-osd-status.png"]
+[thumbnail="screenshot/gui-ceph-osd-status.png"]
via GUI or via CLI as follows:
among your, at least three nodes (4 OSDs on each node).
If the disk was used before (eg. ZFS/RAID/OSD), to remove partition table, boot
-sector and any OSD leftover the following commands should be sufficient.
+sector and any OSD leftover the following command should be sufficient.
[source,bash]
----
-dd if=/dev/zero of=/dev/sd[X] bs=1M count=200
-ceph-disk zap /dev/sd[X]
+ceph-volume lvm zap /dev/sd[X] --destroy
----
-WARNING: The above commands will destroy data on the disk!
+WARNING: The above command will destroy data on the disk!
Ceph Bluestore
~~~~~~~~~~~~~~
Starting with the Ceph Kraken release, a new Ceph OSD storage type was
introduced, the so called Bluestore
footnote:[Ceph Bluestore http://ceph.com/community/new-luminous-bluestore/].
-This is the default when creating OSDs in Ceph luminous.
+This is the default when creating OSDs since Ceph Luminous.
[source,bash]
----
pveceph createosd /dev/sd[X]
----
-NOTE: In order to select a disk in the GUI, to be more failsafe, the disk needs
-to have a GPT footnoteref:[GPT, GPT partition table
-https://en.wikipedia.org/wiki/GUID_Partition_Table] partition table. You can
-create this with `gdisk /dev/sd(x)`. If there is no GPT, you cannot select the
-disk as DB/WAL.
+Block.db and block.wal
+^^^^^^^^^^^^^^^^^^^^^^
If you want to use a separate DB/WAL device for your OSDs, you can specify it
-through the '-journal_dev' option. The WAL is placed with the DB, if not
+through the '-db_dev' and '-wal_dev' options. The WAL is placed with the DB, if not
specified separately.
[source,bash]
----
-pveceph createosd /dev/sd[X] -journal_dev /dev/sd[Y]
+pveceph createosd /dev/sd[X] -db_dev /dev/sd[Y] -wal_dev /dev/sd[Z]
----
+You can directly choose the size for those with the '-db_size' and '-wal_size'
+paremeters respectively. If they are not given the following values (in order)
+will be used:
+
+* bluestore_block_{db,wal}_size from ceph configuration...
+** ... database, section 'osd'
+** ... database, section 'global'
+** ... file, section 'osd'
+** ... file, section 'global'
+* 10% (DB)/1% (WAL) of OSD size
+
NOTE: The DB stores BlueStore’s internal metadata and the WAL is BlueStore’s
-internal journal or write-ahead log. It is recommended to use a fast SSDs or
+internal journal or write-ahead log. It is recommended to use a fast SSD or
NVRAM for better performance.
Ceph Filestore
-~~~~~~~~~~~~~
-Till Ceph luminous, Filestore was used as storage type for Ceph OSDs. It can
-still be used and might give better performance in small setups, when backed by
-a NVMe SSD or similar.
-
-[source,bash]
-----
-pveceph createosd /dev/sd[X] -bluestore 0
-----
-
-NOTE: In order to select a disk in the GUI, the disk needs to have a
-GPT footnoteref:[GPT] partition table. You can
-create this with `gdisk /dev/sd(x)`. If there is no GPT, you cannot select the
-disk as journal. Currently the journal size is fixed to 5 GB.
-
-If you want to use a dedicated SSD journal disk:
-
-[source,bash]
-----
-pveceph createosd /dev/sd[X] -journal_dev /dev/sd[Y] -bluestore 0
-----
+~~~~~~~~~~~~~~
-Example: Use /dev/sdf as data disk (4TB) and /dev/sdb is the dedicated SSD
-journal disk.
+Before Ceph Luminous, Filestore was used as default storage type for Ceph OSDs.
+Starting with Ceph Nautilus, {pve} does not support creating such OSDs with
+'pveceph' anymore. If you still want to create filestore OSDs, use
+'ceph-volume' directly.
[source,bash]
----
-pveceph createosd /dev/sdf -journal_dev /dev/sdb -bluestore 0
+ceph-volume lvm create --filestore --data /dev/sd[X] --journal /dev/sd[Y]
----
-This partitions the disk (data and journal partition), creates
-filesystems and starts the OSD, afterwards it is running and fully
-functional.
-
-NOTE: This command refuses to initialize disk when it detects existing data. So
-if you want to overwrite a disk you should remove existing data first. You can
-do that using: 'ceph-disk zap /dev/sd[X]'
-
-You can create OSDs containing both journal and data partitions or you
-can place the journal on a dedicated SSD. Using a SSD journal disk is
-highly recommended to achieve good performance.
-
-
[[pve_ceph_pools]]
Creating Ceph Pools
-------------------
-[thumbnail="gui-ceph-pools.png"]
+[thumbnail="screenshot/gui-ceph-pools.png"]
A pool is a logical group for storing objects. It holds **P**lacement
-**G**roups (PG), a collection of objects.
+**G**roups (`PG`, `pg_num`), a collection of objects.
-When no options are given, we set a
-default of **64 PGs**, a **size of 3 replicas** and a **min_size of 2 replicas**
-for serving objects in a degraded state.
+When no options are given, we set a default of **128 PGs**, a **size of 3
+replicas** and a **min_size of 2 replicas** for serving objects in a degraded
+state.
-NOTE: The default number of PGs works for 2-6 disks. Ceph throws a
-"HEALTH_WARNING" if you have too few or too many PGs in your cluster.
+NOTE: The default number of PGs works for 2-5 disks. Ceph throws a
+'HEALTH_WARNING' if you have too few or too many PGs in your cluster.
It is advised to calculate the PG number depending on your setup, you can find
the formula and the PG calculator footnote:[PG calculator
http://docs.ceph.com/docs/luminous/rados/operations/pools/]
manual.
+[[pve_ceph_device_classes]]
Ceph CRUSH & device classes
---------------------------
The foundation of Ceph is its algorithm, **C**ontrolled **R**eplication
Ceph Client
-----------
-[thumbnail="gui-ceph-log.png"]
+[thumbnail="screenshot/gui-ceph-log.png"]
You can then configure {pve} to use such pools to store VM or
Container images. Simply use the GUI too add a new `RBD` storage (see
cp /etc/ceph/ceph.client.admin.keyring /etc/pve/priv/ceph/my-ceph-storage.keyring
----
+[[pveceph_fs]]
+CephFS
+------
+
+Ceph provides also a filesystem running on top of the same object storage as
+RADOS block devices do. A **M**eta**d**ata **S**erver (`MDS`) is used to map
+the RADOS backed objects to files and directories, allowing to provide a
+POSIX-compliant replicated filesystem. This allows one to have a clustered
+highly available shared filesystem in an easy way if ceph is already used. Its
+Metadata Servers guarantee that files get balanced out over the whole Ceph
+cluster, this way even high load will not overload a single host, which can be
+an issue with traditional shared filesystem approaches, like `NFS`, for
+example.
+
+{pve} supports both, using an existing xref:storage_cephfs[CephFS as storage]
+to save backups, ISO files or container templates and creating a
+hyper-converged CephFS itself.
+
+
+[[pveceph_fs_mds]]
+Metadata Server (MDS)
+~~~~~~~~~~~~~~~~~~~~~
+
+CephFS needs at least one Metadata Server to be configured and running to be
+able to work. One can simply create one through the {pve} web GUI's `Node ->
+CephFS` panel or on the command line with:
+
+----
+pveceph mds create
+----
+
+Multiple metadata servers can be created in a cluster. But with the default
+settings only one can be active at any time. If an MDS, or its node, becomes
+unresponsive (or crashes), another `standby` MDS will get promoted to `active`.
+One can speed up the hand-over between the active and a standby MDS up by using
+the 'hotstandby' parameter option on create, or if you have already created it
+you may set/add:
+
+----
+mds standby replay = true
+----
+
+in the ceph.conf respective MDS section. With this enabled, this specific MDS
+will always poll the active one, so that it can take over faster as it is in a
+`warm` state. But naturally, the active polling will cause some additional
+performance impact on your system and active `MDS`.
+
+Multiple Active MDS
+^^^^^^^^^^^^^^^^^^^
+
+Since Luminous (12.2.x) you can also have multiple active metadata servers
+running, but this is normally only useful for a high count on parallel clients,
+as else the `MDS` seldom is the bottleneck. If you want to set this up please
+refer to the ceph documentation. footnote:[Configuring multiple active MDS
+daemons http://docs.ceph.com/docs/luminous/cephfs/multimds/]
+
+[[pveceph_fs_create]]
+Create a CephFS
+~~~~~~~~~~~~~~~
+
+With {pve}'s CephFS integration into you can create a CephFS easily over the
+Web GUI, the CLI or an external API interface. Some prerequisites are required
+for this to work:
+
+.Prerequisites for a successful CephFS setup:
+- xref:pve_ceph_install[Install Ceph packages], if this was already done some
+ time ago you might want to rerun it on an up to date system to ensure that
+ also all CephFS related packages get installed.
+- xref:pve_ceph_monitors[Setup Monitors]
+- xref:pve_ceph_monitors[Setup your OSDs]
+- xref:pveceph_fs_mds[Setup at least one MDS]
+
+After this got all checked and done you can simply create a CephFS through
+either the Web GUI's `Node -> CephFS` panel or the command line tool `pveceph`,
+for example with:
+
+----
+pveceph fs create --pg_num 128 --add-storage
+----
+
+This creates a CephFS named `'cephfs'' using a pool for its data named
+`'cephfs_data'' with `128` placement groups and a pool for its metadata named
+`'cephfs_metadata'' with one quarter of the data pools placement groups (`32`).
+Check the xref:pve_ceph_pools[{pve} managed Ceph pool chapter] or visit the
+Ceph documentation for more information regarding a fitting placement group
+number (`pg_num`) for your setup footnote:[Ceph Placement Groups
+http://docs.ceph.com/docs/luminous/rados/operations/placement-groups/].
+Additionally, the `'--add-storage'' parameter will add the CephFS to the {pve}
+storage configuration after it was created successfully.
+
+Destroy CephFS
+~~~~~~~~~~~~~~
+
+WARNING: Destroying a CephFS will render all its data unusable, this cannot be
+undone!
+
+If you really want to destroy an existing CephFS you first need to stop, or
+destroy, all metadata server (`M̀DS`). You can destroy them either over the Web
+GUI or the command line interface, with:
+
+----
+pveceph mds destroy NAME
+----
+on each {pve} node hosting a MDS daemon.
+
+Then, you can remove (destroy) CephFS by issuing a:
+
+----
+ceph fs rm NAME --yes-i-really-mean-it
+----
+on a single node hosting Ceph. After this you may want to remove the created
+data and metadata pools, this can be done either over the Web GUI or the CLI
+with:
+
+----
+pveceph pool destroy NAME
+----
+
+
+Ceph monitoring and troubleshooting
+-----------------------------------
+A good start is to continuosly monitor the ceph health from the start of
+initial deployment. Either through the ceph tools itself, but also by accessing
+the status through the {pve} link:api-viewer/index.html[API].
+
+The following ceph commands below can be used to see if the cluster is healthy
+('HEALTH_OK'), if there are warnings ('HEALTH_WARN'), or even errors
+('HEALTH_ERR'). If the cluster is in an unhealthy state the status commands
+below will also give you an overview on the current events and actions take.
+
+----
+# single time output
+pve# ceph -s
+# continuously output status changes (press CTRL+C to stop)
+pve# ceph -w
+----
+
+To get a more detailed view, every ceph service has a log file under
+`/var/log/ceph/` and if there is not enough detail, the log level can be
+adjusted footnote:[Ceph log and debugging http://docs.ceph.com/docs/luminous/rados/troubleshooting/log-and-debug/].
+
+You can find more information about troubleshooting
+footnote:[Ceph troubleshooting http://docs.ceph.com/docs/luminous/rados/troubleshooting/]
+a Ceph cluster on its website.
+
ifdef::manvolnum[]
include::pve-copyright.adoc[]
projects / pve-docs.git / blobdiff