10 pveceph - Manage Ceph Services on Proxmox VE Nodes
15 include::pveceph.1-synopsis.adoc[]
21 Deploy Hyper-Converged Ceph Cluster
22 ===================================
26 [thumbnail="screenshot/gui-ceph-status.png"]
28 {pve} unifies your compute and storage systems, that is, you can use the same
29 physical nodes within a cluster for both computing (processing VMs and
30 containers) and replicated storage. The traditional silos of compute and
31 storage resources can be wrapped up into a single hyper-converged appliance.
32 Separate storage networks (SANs) and connections via network attached storage
33 (NAS) disappear. With the integration of Ceph, an open source software-defined
34 storage platform, {pve} has the ability to run and manage Ceph storage directly
35 on the hypervisor nodes.
37 Ceph is a distributed object store and file system designed to provide
38 excellent performance, reliability and scalability.
40 .Some advantages of Ceph on {pve} are:
41 - Easy setup and management via CLI and GUI
45 - Scalable to the exabyte level
46 - Setup pools with different performance and redundancy characteristics
47 - Data is replicated, making it fault tolerant
48 - Runs on commodity hardware
49 - No need for hardware RAID controllers
52 For small to medium-sized deployments, it is possible to install a Ceph server for
53 RADOS Block Devices (RBD) directly on your {pve} cluster nodes (see
54 xref:ceph_rados_block_devices[Ceph RADOS Block Devices (RBD)]). Recent
55 hardware has a lot of CPU power and RAM, so running storage services
56 and VMs on the same node is possible.
58 To simplify management, we provide 'pveceph' - a tool for installing and
59 managing {ceph} services on {pve} nodes.
61 .Ceph consists of multiple Daemons, for use as an RBD storage:
62 - Ceph Monitor (ceph-mon)
63 - Ceph Manager (ceph-mgr)
64 - Ceph OSD (ceph-osd; Object Storage Daemon)
66 TIP: We highly recommend to get familiar with Ceph
67 footnote:[Ceph intro {cephdocs-url}/start/intro/],
69 footnote:[Ceph architecture {cephdocs-url}/architecture/]
71 footnote:[Ceph glossary {cephdocs-url}/glossary].
77 To build a hyper-converged Proxmox + Ceph Cluster, you must use at least
78 three (preferably) identical servers for the setup.
80 Check also the recommendations from
81 {cephdocs-url}/start/hardware-recommendations/[Ceph's website].
84 A high CPU core frequency reduces latency and should be preferred. As a simple
85 rule of thumb, you should assign a CPU core (or thread) to each Ceph service to
86 provide enough resources for stable and durable Ceph performance.
89 Especially in a hyper-converged setup, the memory consumption needs to be
90 carefully monitored. In addition to the predicted memory usage of virtual
91 machines and containers, you must also account for having enough memory
92 available for Ceph to provide excellent and stable performance.
94 As a rule of thumb, for roughly **1 TiB of data, 1 GiB of memory** will be used
95 by an OSD. Especially during recovery, rebalancing or backfilling.
97 The daemon itself will use additional memory. The Bluestore backend of the
98 daemon requires by default **3-5 GiB of memory** (adjustable). In contrast, the
99 legacy Filestore backend uses the OS page cache and the memory consumption is
100 generally related to PGs of an OSD daemon.
103 We recommend a network bandwidth of at least 10 GbE or more, which is used
104 exclusively for Ceph. A meshed network setup
105 footnote:[Full Mesh Network for Ceph {webwiki-url}Full_Mesh_Network_for_Ceph_Server]
106 is also an option if there are no 10 GbE switches available.
108 The volume of traffic, especially during recovery, will interfere with other
109 services on the same network and may even break the {pve} cluster stack.
111 Furthermore, you should estimate your bandwidth needs. While one HDD might not
112 saturate a 1 Gb link, multiple HDD OSDs per node can, and modern NVMe SSDs will
113 even saturate 10 Gbps of bandwidth quickly. Deploying a network capable of even
114 more bandwidth will ensure that this isn't your bottleneck and won't be anytime
115 soon. 25, 40 or even 100 Gbps are possible.
118 When planning the size of your Ceph cluster, it is important to take the
119 recovery time into consideration. Especially with small clusters, recovery
120 might take long. It is recommended that you use SSDs instead of HDDs in small
121 setups to reduce recovery time, minimizing the likelihood of a subsequent
122 failure event during recovery.
124 In general SSDs will provide more IOPs than spinning disks. With this in mind,
125 in addition to the higher cost, it may make sense to implement a
126 xref:pve_ceph_device_classes[class based] separation of pools. Another way to
127 speed up OSDs is to use a faster disk as a journal or
128 DB/**W**rite-**A**head-**L**og device, see xref:pve_ceph_osds[creating Ceph
129 OSDs]. If a faster disk is used for multiple OSDs, a proper balance between OSD
130 and WAL / DB (or journal) disk must be selected, otherwise the faster disk
131 becomes the bottleneck for all linked OSDs.
133 Aside from the disk type, Ceph performs best with an even sized and distributed
134 amount of disks per node. For example, 4 x 500 GB disks within each node is
135 better than a mixed setup with a single 1 TB and three 250 GB disk.
137 You also need to balance OSD count and single OSD capacity. More capacity
138 allows you to increase storage density, but it also means that a single OSD
139 failure forces Ceph to recover more data at once.
142 As Ceph handles data object redundancy and multiple parallel writes to disks
143 (OSDs) on its own, using a RAID controller normally doesn’t improve
144 performance or availability. On the contrary, Ceph is designed to handle whole
145 disks on it's own, without any abstraction in between. RAID controllers are not
146 designed for the Ceph workload and may complicate things and sometimes even
147 reduce performance, as their write and caching algorithms may interfere with
150 WARNING: Avoid RAID controllers. Use host bus adapter (HBA) instead.
152 NOTE: The above recommendations should be seen as a rough guidance for choosing
153 hardware. Therefore, it is still essential to adapt it to your specific needs.
154 You should test your setup and monitor health and performance continuously.
156 [[pve_ceph_install_wizard]]
157 Initial Ceph Installation & Configuration
158 -----------------------------------------
160 [thumbnail="screenshot/gui-node-ceph-install.png"]
162 With {pve} you have the benefit of an easy to use installation wizard
163 for Ceph. Click on one of your cluster nodes and navigate to the Ceph
164 section in the menu tree. If Ceph is not already installed, you will see a
165 prompt offering to do so.
167 The wizard is divided into multiple sections, where each needs to
168 finish successfully, in order to use Ceph. After starting the installation,
169 the wizard will download and install all the required packages from {pve}'s Ceph
172 After finishing the first step, you will need to create a configuration.
173 This step is only needed once per cluster, as this configuration is distributed
174 automatically to all remaining cluster members through {pve}'s clustered
175 xref:chapter_pmxcfs[configuration file system (pmxcfs)].
177 The configuration step includes the following settings:
179 * *Public Network:* You can set up a dedicated network for Ceph. This
180 setting is required. Separating your Ceph traffic is highly recommended.
181 Otherwise, it could cause trouble with other latency dependent services,
182 for example, cluster communication may decrease Ceph's performance.
184 [thumbnail="screenshot/gui-node-ceph-install-wizard-step2.png"]
186 * *Cluster Network:* As an optional step, you can go even further and
187 separate the xref:pve_ceph_osds[OSD] replication & heartbeat traffic
188 as well. This will relieve the public network and could lead to
189 significant performance improvements, especially in large clusters.
191 You have two more options which are considered advanced and therefore
192 should only changed if you know what you are doing.
194 * *Number of replicas*: Defines how often an object is replicated
195 * *Minimum replicas*: Defines the minimum number of required replicas
196 for I/O to be marked as complete.
198 Additionally, you need to choose your first monitor node. This step is required.
200 That's it. You should now see a success page as the last step, with further
201 instructions on how to proceed. Your system is now ready to start using Ceph.
202 To get started, you will need to create some additional xref:pve_ceph_monitors[monitors],
203 xref:pve_ceph_osds[OSDs] and at least one xref:pve_ceph_pools[pool].
205 The rest of this chapter will guide you through getting the most out of
206 your {pve} based Ceph setup. This includes the aforementioned tips and
207 more, such as xref:pveceph_fs[CephFS], which is a helpful addition to your
211 Installation of Ceph Packages
212 -----------------------------
213 Use the {pve} Ceph installation wizard (recommended) or run the following
214 command on each node:
221 This sets up an `apt` package repository in
222 `/etc/apt/sources.list.d/ceph.list` and installs the required software.
225 Create initial Ceph configuration
226 ---------------------------------
228 [thumbnail="screenshot/gui-ceph-config.png"]
230 Use the {pve} Ceph installation wizard (recommended) or run the
231 following command on one node:
235 pveceph init --network 10.10.10.0/24
238 This creates an initial configuration at `/etc/pve/ceph.conf` with a
239 dedicated network for Ceph. This file is automatically distributed to
240 all {pve} nodes, using xref:chapter_pmxcfs[pmxcfs]. The command also
241 creates a symbolic link at `/etc/ceph/ceph.conf`, which points to that file.
242 Thus, you can simply run Ceph commands without the need to specify a
246 [[pve_ceph_monitors]]
249 The Ceph Monitor (MON)
250 footnote:[Ceph Monitor {cephdocs-url}/start/intro/]
251 maintains a master copy of the cluster map. For high availability, you need at
252 least 3 monitors. One monitor will already be installed if you
253 used the installation wizard. You won't need more than 3 monitors, as long
254 as your cluster is small to medium-sized. Only really large clusters will
255 require more than this.
258 [[pveceph_create_mon]]
262 [thumbnail="screenshot/gui-ceph-monitor.png"]
264 On each node where you want to place a monitor (three monitors are recommended),
265 create one by using the 'Ceph -> Monitor' tab in the GUI or run:
273 [[pveceph_destroy_mon]]
277 To remove a Ceph Monitor via the GUI, first select a node in the tree view and
278 go to the **Ceph -> Monitor** panel. Select the MON and click the **Destroy**
281 To remove a Ceph Monitor via the CLI, first connect to the node on which the MON
282 is running. Then execute the following command:
288 NOTE: At least three Monitors are needed for quorum.
295 The Manager daemon runs alongside the monitors. It provides an interface to
296 monitor the cluster. Since the release of Ceph luminous, at least one ceph-mgr
297 footnote:[Ceph Manager {cephdocs-url}/mgr/] daemon is
300 [[pveceph_create_mgr]]
304 Multiple Managers can be installed, but only one Manager is active at any given
312 NOTE: It is recommended to install the Ceph Manager on the monitor nodes. For
313 high availability install more then one manager.
316 [[pveceph_destroy_mgr]]
320 To remove a Ceph Manager via the GUI, first select a node in the tree view and
321 go to the **Ceph -> Monitor** panel. Select the Manager and click the
324 To remove a Ceph Monitor via the CLI, first connect to the node on which the
325 Manager is running. Then execute the following command:
331 NOTE: While a manager is not a hard-dependency, it is crucial for a Ceph cluster,
332 as it handles important features like PG-autoscaling, device health monitoring,
338 Ceph **O**bject **S**torage **D**aemons store objects for Ceph over the
339 network. It is recommended to use one OSD per physical disk.
341 NOTE: By default an object is 4 MiB in size.
343 [[pve_ceph_osd_create]]
347 [thumbnail="screenshot/gui-ceph-osd-status.png"]
349 You can create an OSD either via the {pve} web-interface or via the CLI using
350 `pveceph`. For example:
354 pveceph osd create /dev/sd[X]
357 TIP: We recommend a Ceph cluster with at least three nodes and at least 12
358 OSDs, evenly distributed among the nodes.
360 If the disk was in use before (for example, for ZFS or as an OSD) you first need
361 to zap all traces of that usage. To remove the partition table, boot sector and
362 any other OSD leftover, you can use the following command:
366 ceph-volume lvm zap /dev/sd[X] --destroy
369 WARNING: The above command will destroy all data on the disk!
373 Starting with the Ceph Kraken release, a new Ceph OSD storage type was
374 introduced called Bluestore
375 footnote:[Ceph Bluestore https://ceph.com/community/new-luminous-bluestore/].
376 This is the default when creating OSDs since Ceph Luminous.
380 pveceph osd create /dev/sd[X]
383 .Block.db and block.wal
385 If you want to use a separate DB/WAL device for your OSDs, you can specify it
386 through the '-db_dev' and '-wal_dev' options. The WAL is placed with the DB, if
387 not specified separately.
391 pveceph osd create /dev/sd[X] -db_dev /dev/sd[Y] -wal_dev /dev/sd[Z]
394 You can directly choose the size of those with the '-db_size' and '-wal_size'
395 parameters respectively. If they are not given, the following values (in order)
398 * bluestore_block_{db,wal}_size from Ceph configuration...
399 ** ... database, section 'osd'
400 ** ... database, section 'global'
401 ** ... file, section 'osd'
402 ** ... file, section 'global'
403 * 10% (DB)/1% (WAL) of OSD size
405 NOTE: The DB stores BlueStore’s internal metadata, and the WAL is BlueStore’s
406 internal journal or write-ahead log. It is recommended to use a fast SSD or
407 NVRAM for better performance.
412 Before Ceph Luminous, Filestore was used as the default storage type for Ceph OSDs.
413 Starting with Ceph Nautilus, {pve} does not support creating such OSDs with
414 'pveceph' anymore. If you still want to create filestore OSDs, use
415 'ceph-volume' directly.
419 ceph-volume lvm create --filestore --data /dev/sd[X] --journal /dev/sd[Y]
422 [[pve_ceph_osd_destroy]]
426 To remove an OSD via the GUI, first select a {PVE} node in the tree view and go
427 to the **Ceph -> OSD** panel. Then select the OSD to destroy and click the **OUT**
428 button. Once the OSD status has changed from `in` to `out`, click the **STOP**
429 button. Finally, after the status has changed from `up` to `down`, select
430 **Destroy** from the `More` drop-down menu.
432 To remove an OSD via the CLI run the following commands.
437 systemctl stop ceph-osd@<ID>.service
440 NOTE: The first command instructs Ceph not to include the OSD in the data
441 distribution. The second command stops the OSD service. Until this time, no
444 The following command destroys the OSD. Specify the '-cleanup' option to
445 additionally destroy the partition table.
449 pveceph osd destroy <ID>
452 WARNING: The above command will destroy all data on the disk!
458 A pool is a logical group for storing objects. It holds a collection of objects,
459 known as **P**lacement **G**roups (`PG`, `pg_num`).
462 Create and Edit Pools
463 ~~~~~~~~~~~~~~~~~~~~~
465 You can create pools from the command line or the web-interface of any {pve}
466 host under **Ceph -> Pools**.
468 [thumbnail="screenshot/gui-ceph-pools.png"]
470 When no options are given, we set a default of **128 PGs**, a **size of 3
471 replicas** and a **min_size of 2 replicas**, to ensure no data loss occurs if
474 WARNING: **Do not set a min_size of 1**. A replicated pool with min_size of 1
475 allows I/O on an object when it has only 1 replica, which could lead to data
476 loss, incomplete PGs or unfound objects.
478 It is advised that you calculate the PG number based on your setup. You can
479 find the formula and the PG calculator footnote:[PG calculator
480 https://ceph.com/pgcalc/] online. From Ceph Nautilus onward, you can change the
481 number of PGs footnoteref:[placement_groups,Placement Groups
482 {cephdocs-url}/rados/operations/placement-groups/] after the setup.
484 In addition to manual adjustment, the PG autoscaler
485 footnoteref:[autoscaler,Automated Scaling
486 {cephdocs-url}/rados/operations/placement-groups/#automated-scaling] can
487 automatically scale the PG count for a pool in the background.
489 .Example for creating a pool over the CLI
492 pveceph pool create <name> --add_storages
495 TIP: If you would also like to automatically define a storage for your
496 pool, keep the `Add as Storage' checkbox checked in the web-interface, or use the
497 command line option '--add_storages' at pool creation.
500 Name:: The name of the pool. This must be unique and can't be changed afterwards.
501 Size:: The number of replicas per object. Ceph always tries to have this many
502 copies of an object. Default: `3`.
503 PG Autoscale Mode:: The automatic PG scaling mode footnoteref:[autoscaler] of
504 the pool. If set to `warn`, it produces a warning message when a pool
505 has a non-optimal PG count. Default: `warn`.
506 Add as Storage:: Configure a VM or container storage using the new pool.
507 Default: `true` (only visible on creation).
510 Min. Size:: The minimum number of replicas per object. Ceph will reject I/O on
511 the pool if a PG has less than this many replicas. Default: `2`.
512 Crush Rule:: The rule to use for mapping object placement in the cluster. These
513 rules define how data is placed within the cluster. See
514 xref:pve_ceph_device_classes[Ceph CRUSH & device classes] for information on
516 # of PGs:: The number of placement groups footnoteref:[placement_groups] that
517 the pool should have at the beginning. Default: `128`.
518 Target Size Ratio:: The ratio of data that is expected in the pool. The PG
519 autoscaler uses the ratio relative to other ratio sets. It takes precedence
520 over the `target size` if both are set.
521 Target Size:: The estimated amount of data expected in the pool. The PG
522 autoscaler uses this size to estimate the optimal PG count.
523 Min. # of PGs:: The minimum number of placement groups. This setting is used to
524 fine-tune the lower bound of the PG count for that pool. The PG autoscaler
525 will not merge PGs below this threshold.
527 Further information on Ceph pool handling can be found in the Ceph pool
528 operation footnote:[Ceph pool operation
529 {cephdocs-url}/rados/operations/pools/]
536 To destroy a pool via the GUI, select a node in the tree view and go to the
537 **Ceph -> Pools** panel. Select the pool to destroy and click the **Destroy**
538 button. To confirm the destruction of the pool, you need to enter the pool name.
540 Run the following command to destroy a pool. Specify the '-remove_storages' to
541 also remove the associated storage.
545 pveceph pool destroy <name>
548 NOTE: Pool deletion runs in the background and can take some time.
549 You will notice the data usage in the cluster decreasing throughout this
556 The PG autoscaler allows the cluster to consider the amount of (expected) data
557 stored in each pool and to choose the appropriate pg_num values automatically.
559 You may need to activate the PG autoscaler module before adjustments can take
564 ceph mgr module enable pg_autoscaler
567 The autoscaler is configured on a per pool basis and has the following modes:
570 warn:: A health warning is issued if the suggested `pg_num` value differs too
571 much from the current value.
572 on:: The `pg_num` is adjusted automatically with no need for any manual
574 off:: No automatic `pg_num` adjustments are made, and no warning will be issued
575 if the PG count is not optimal.
577 The scaling factor can be adjusted to facilitate future data storage with the
578 `target_size`, `target_size_ratio` and the `pg_num_min` options.
580 WARNING: By default, the autoscaler considers tuning the PG count of a pool if
581 it is off by a factor of 3. This will lead to a considerable shift in data
582 placement and might introduce a high load on the cluster.
584 You can find a more in-depth introduction to the PG autoscaler on Ceph's Blog -
585 https://ceph.io/rados/new-in-nautilus-pg-merging-and-autotuning/[New in
586 Nautilus: PG merging and autotuning].
589 [[pve_ceph_device_classes]]
590 Ceph CRUSH & device classes
591 ---------------------------
593 https://ceph.com/wp-content/uploads/2016/08/weil-crush-sc06.pdf] (**C**ontrolled
594 **R**eplication **U**nder **S**calable **H**ashing) algorithm is at the
597 CRUSH calculates where to store and retrieve data from. This has the
598 advantage that no central indexing service is needed. CRUSH works using a map of
599 OSDs, buckets (device locations) and rulesets (data replication) for pools.
601 NOTE: Further information can be found in the Ceph documentation, under the
602 section CRUSH map footnote:[CRUSH map {cephdocs-url}/rados/operations/crush-map/].
604 This map can be altered to reflect different replication hierarchies. The object
605 replicas can be separated (eg. failure domains), while maintaining the desired
608 A common configuration is to use different classes of disks for different Ceph
609 pools. For this reason, Ceph introduced device classes with luminous, to
610 accommodate the need for easy ruleset generation.
612 The device classes can be seen in the 'ceph osd tree' output. These classes
613 represent their own root bucket, which can be seen with the below command.
617 ceph osd crush tree --show-shadow
620 Example output form the above command:
624 ID CLASS WEIGHT TYPE NAME
625 -16 nvme 2.18307 root default~nvme
626 -13 nvme 0.72769 host sumi1~nvme
627 12 nvme 0.72769 osd.12
628 -14 nvme 0.72769 host sumi2~nvme
629 13 nvme 0.72769 osd.13
630 -15 nvme 0.72769 host sumi3~nvme
631 14 nvme 0.72769 osd.14
632 -1 7.70544 root default
633 -3 2.56848 host sumi1
634 12 nvme 0.72769 osd.12
635 -5 2.56848 host sumi2
636 13 nvme 0.72769 osd.13
637 -7 2.56848 host sumi3
638 14 nvme 0.72769 osd.14
641 To instruct a pool to only distribute objects on a specific device class, you
642 first need to create a ruleset for the device class:
646 ceph osd crush rule create-replicated <rule-name> <root> <failure-domain> <class>
649 [frame="none",grid="none", align="left", cols="30%,70%"]
651 |<rule-name>|name of the rule, to connect with a pool (seen in GUI & CLI)
652 |<root>|which crush root it should belong to (default ceph root "default")
653 |<failure-domain>|at which failure-domain the objects should be distributed (usually host)
654 |<class>|what type of OSD backing store to use (eg. nvme, ssd, hdd)
657 Once the rule is in the CRUSH map, you can tell a pool to use the ruleset.
661 ceph osd pool set <pool-name> crush_rule <rule-name>
664 TIP: If the pool already contains objects, these must be moved accordingly.
665 Depending on your setup, this may introduce a big performance impact on your
666 cluster. As an alternative, you can create a new pool and move disks separately.
672 [thumbnail="screenshot/gui-ceph-log.png"]
674 Following the setup from the previous sections, you can configure {pve} to use
675 such pools to store VM and Container images. Simply use the GUI to add a new
676 `RBD` storage (see section xref:ceph_rados_block_devices[Ceph RADOS Block
679 You also need to copy the keyring to a predefined location for an external Ceph
680 cluster. If Ceph is installed on the Proxmox nodes itself, then this will be
683 NOTE: The filename needs to be `<storage_id> + `.keyring`, where `<storage_id>` is
684 the expression after 'rbd:' in `/etc/pve/storage.cfg`. In the following example,
685 `my-ceph-storage` is the `<storage_id>`:
689 mkdir /etc/pve/priv/ceph
690 cp /etc/ceph/ceph.client.admin.keyring /etc/pve/priv/ceph/my-ceph-storage.keyring
697 Ceph also provides a filesystem, which runs on top of the same object storage as
698 RADOS block devices do. A **M**eta**d**ata **S**erver (`MDS`) is used to map the
699 RADOS backed objects to files and directories, allowing Ceph to provide a
700 POSIX-compliant, replicated filesystem. This allows you to easily configure a
701 clustered, highly available, shared filesystem. Ceph's Metadata Servers
702 guarantee that files are evenly distributed over the entire Ceph cluster. As a
703 result, even cases of high load will not overwhelm a single host, which can be
704 an issue with traditional shared filesystem approaches, for example `NFS`.
706 [thumbnail="screenshot/gui-node-ceph-cephfs-panel.png"]
708 {pve} supports both creating a hyper-converged CephFS and using an existing
709 xref:storage_cephfs[CephFS as storage] to save backups, ISO files, and container
714 Metadata Server (MDS)
715 ~~~~~~~~~~~~~~~~~~~~~
717 CephFS needs at least one Metadata Server to be configured and running, in order
718 to function. You can create an MDS through the {pve} web GUI's `Node
719 -> CephFS` panel or from the command line with:
725 Multiple metadata servers can be created in a cluster, but with the default
726 settings, only one can be active at a time. If an MDS or its node becomes
727 unresponsive (or crashes), another `standby` MDS will get promoted to `active`.
728 You can speed up the handover between the active and standby MDS by using
729 the 'hotstandby' parameter option on creation, or if you have already created it
733 mds standby replay = true
736 in the respective MDS section of `/etc/pve/ceph.conf`. With this enabled, the
737 specified MDS will remain in a `warm` state, polling the active one, so that it
738 can take over faster in case of any issues.
740 NOTE: This active polling will have an additional performance impact on your
741 system and the active `MDS`.
745 Since Luminous (12.2.x) you can have multiple active metadata servers
746 running at once, but this is normally only useful if you have a high amount of
747 clients running in parallel. Otherwise the `MDS` is rarely the bottleneck in a
748 system. If you want to set this up, please refer to the Ceph documentation.
749 footnote:[Configuring multiple active MDS daemons
750 {cephdocs-url}/cephfs/multimds/]
752 [[pveceph_fs_create]]
756 With {pve}'s integration of CephFS, you can easily create a CephFS using the
757 web interface, CLI or an external API interface. Some prerequisites are required
760 .Prerequisites for a successful CephFS setup:
761 - xref:pve_ceph_install[Install Ceph packages] - if this was already done some
762 time ago, you may want to rerun it on an up-to-date system to
763 ensure that all CephFS related packages get installed.
764 - xref:pve_ceph_monitors[Setup Monitors]
765 - xref:pve_ceph_monitors[Setup your OSDs]
766 - xref:pveceph_fs_mds[Setup at least one MDS]
768 After this is complete, you can simply create a CephFS through
769 either the Web GUI's `Node -> CephFS` panel or the command line tool `pveceph`,
773 pveceph fs create --pg_num 128 --add-storage
776 This creates a CephFS named 'cephfs', using a pool for its data named
777 'cephfs_data' with '128' placement groups and a pool for its metadata named
778 'cephfs_metadata' with one quarter of the data pool's placement groups (`32`).
779 Check the xref:pve_ceph_pools[{pve} managed Ceph pool chapter] or visit the
780 Ceph documentation for more information regarding an appropriate placement group
781 number (`pg_num`) for your setup footnoteref:[placement_groups].
782 Additionally, the '--add-storage' parameter will add the CephFS to the {pve}
783 storage configuration after it has been created successfully.
788 WARNING: Destroying a CephFS will render all of its data unusable. This cannot be
791 If you really want to destroy an existing CephFS, you first need to stop or
792 destroy all metadata servers (`M̀DS`). You can destroy them either via the web
793 interface or via the command line interface, by issuing
796 pveceph mds destroy NAME
798 on each {pve} node hosting an MDS daemon.
800 Then, you can remove (destroy) the CephFS by issuing
803 ceph fs rm NAME --yes-i-really-mean-it
805 on a single node hosting Ceph. After this, you may want to remove the created
806 data and metadata pools, this can be done either over the Web GUI or the CLI
810 pveceph pool destroy NAME
820 One of the most common maintenance tasks in Ceph is to replace the disk of an
821 OSD. If a disk is already in a failed state, then you can go ahead and run
822 through the steps in xref:pve_ceph_osd_destroy[Destroy OSDs]. Ceph will recreate
823 those copies on the remaining OSDs if possible. This rebalancing will start as
824 soon as an OSD failure is detected or an OSD was actively stopped.
826 NOTE: With the default size/min_size (3/2) of a pool, recovery only starts when
827 `size + 1` nodes are available. The reason for this is that the Ceph object
828 balancer xref:pve_ceph_device_classes[CRUSH] defaults to a full node as
831 To replace a functioning disk from the GUI, go through the steps in
832 xref:pve_ceph_osd_destroy[Destroy OSDs]. The only addition is to wait until
833 the cluster shows 'HEALTH_OK' before stopping the OSD to destroy it.
835 On the command line, use the following commands:
838 ceph osd out osd.<id>
841 You can check with the command below if the OSD can be safely removed.
844 ceph osd safe-to-destroy osd.<id>
847 Once the above check tells you that it is safe to remove the OSD, you can
848 continue with the following commands:
851 systemctl stop ceph-osd@<id>.service
852 pveceph osd destroy <id>
855 Replace the old disk with the new one and use the same procedure as described
856 in xref:pve_ceph_osd_create[Create OSDs].
861 It is good practice to run 'fstrim' (discard) regularly on VMs and containers.
862 This releases data blocks that the filesystem isn’t using anymore. It reduces
863 data usage and resource load. Most modern operating systems issue such discard
864 commands to their disks regularly. You only need to ensure that the Virtual
865 Machines enable the xref:qm_hard_disk_discard[disk discard option].
871 Ceph ensures data integrity by 'scrubbing' placement groups. Ceph checks every
872 object in a PG for its health. There are two forms of Scrubbing, daily
873 cheap metadata checks and weekly deep data checks. The weekly deep scrub reads
874 the objects and uses checksums to ensure data integrity. If a running scrub
875 interferes with business (performance) needs, you can adjust the time when
876 scrubs footnote:[Ceph scrubbing {cephdocs-url}/rados/configuration/osd-config-ref/#scrubbing]
880 Ceph Monitoring and Troubleshooting
881 -----------------------------------
883 It is important to continuously monitor the health of a Ceph deployment from the
884 beginning, either by using the Ceph tools or by accessing
885 the status through the {pve} link:api-viewer/index.html[API].
887 The following Ceph commands can be used to see if the cluster is healthy
888 ('HEALTH_OK'), if there are warnings ('HEALTH_WARN'), or even errors
889 ('HEALTH_ERR'). If the cluster is in an unhealthy state, the status commands
890 below will also give you an overview of the current events and actions to take.
895 # continuously output status changes (press CTRL+C to stop)
899 To get a more detailed view, every Ceph service has a log file under
900 `/var/log/ceph/`. If more detail is required, the log level can be
901 adjusted footnote:[Ceph log and debugging {cephdocs-url}/rados/troubleshooting/log-and-debug/].
903 You can find more information about troubleshooting
904 footnote:[Ceph troubleshooting {cephdocs-url}/rados/troubleshooting/]
905 a Ceph cluster on the official website.
909 include::pve-copyright.adoc[]