X-Git-Url: https://git.proxmox.com/?p=pve-docs.git;a=blobdiff_plain;f=pveceph.adoc;h=8dc85680ded076094afd9d7afb724f5ccd1761e7;hp=d330dea552848cee6d835430c93eb464de0fb433;hb=31df4fee0443eb4e00fdf2a6cbfc88c2789f5882;hpb=10df14fb23f1d4cb8f80d63c675ea45353ccb7d7 diff --git a/pveceph.adoc b/pveceph.adoc index d330dea..8dc8568 100644 --- a/pveceph.adoc +++ b/pveceph.adoc @@ -18,8 +18,8 @@ DESCRIPTION ----------- endif::manvolnum[] ifndef::manvolnum[] -Manage Ceph Services on Proxmox VE Nodes -======================================== +Deploy Hyper-Converged Ceph Cluster +=================================== :pve-toplevel: endif::manvolnum[] @@ -58,29 +58,82 @@ and VMs on the same node is possible. 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/luminous/start/intro/], for use as a RBD storage: +.Ceph consists of a couple of Daemons footnote:[Ceph intro https://docs.ceph.com/docs/{ceph_codename}/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 highly recommend to get familiar with Ceph's architecture -footnote:[Ceph architecture http://docs.ceph.com/docs/luminous/architecture/] +footnote:[Ceph architecture https://docs.ceph.com/docs/{ceph_codename}/architecture/] and vocabulary -footnote:[Ceph glossary http://docs.ceph.com/docs/luminous/glossary]. +footnote:[Ceph glossary https://docs.ceph.com/docs/{ceph_codename}/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]. +https://docs.ceph.com/docs/{ceph_codename}/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 containers, Ceph needs enough memory available to provide excellent and +stable performance. + +As a rule of thumb, for roughly **1 TiB of data, 1 GiB of memory** will be used +by an OSD. Especially during recovery, rebalancing or backfilling. + +The daemon itself will use additional memory. The Bluestore backend of the +daemon requires by default **3-5 GiB of memory** (adjustable). In contrast, the +legacy Filestore backend uses the OS page cache and the memory consumption is +generally related to PGs of an OSD daemon. + +.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 bandwidth +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 @@ -93,12 +146,69 @@ the ones from Ceph. 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] ---- @@ -109,37 +219,44 @@ This sets up an `apt` package repository in `/etc/apt/sources.list.d/ceph.list` and installs the required software. -Creating initial Ceph configuration ------------------------------------ +Create initial Ceph configuration +--------------------------------- [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="screenshot/gui-ceph-monitor.png"] - +Ceph Monitor +----------- The Ceph Monitor (MON) -footnote:[Ceph Monitor http://docs.ceph.com/docs/luminous/start/intro/] +footnote:[Ceph Monitor https://docs.ceph.com/docs/{ceph_codename}/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 won't need more than 3 monitors as long +as your cluster is small to midsize, only really large clusters will +need more than that. + + +[[pveceph_create_mon]] +Create Monitors +~~~~~~~~~~~~~~~ + +[thumbnail="screenshot/gui-ceph-monitor.png"] 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. @@ -147,35 +264,80 @@ create it by using the 'Ceph -> Monitor' tab in the GUI or run. [source,bash] ---- -pveceph createmon +pveceph mon create ---- -This will also install the needed Ceph Manager ('ceph-mgr') by default. If you -do not want to install a manager, specify the '-exclude-manager' option. +[[pveceph_destroy_mon]] +Destroy Monitors +~~~~~~~~~~~~~~~~ + +To remove a Ceph Monitor via the GUI first select a node in the tree view and +go to the **Ceph -> Monitor** panel. Select the MON and click the **Destroy** +button. + +To remove a Ceph Monitor via the CLI first connect to the node on which the MON +is running. Then execute the following command: +[source,bash] +---- +pveceph mon destroy +---- + +NOTE: At least three Monitors are needed for quorum. [[pve_ceph_manager]] -Creating Ceph Manager ----------------------- +Ceph Manager +------------ +The Manager daemon runs alongside the monitors. It provides an interface to +monitor the cluster. Since the Ceph luminous release at least one ceph-mgr +footnote:[Ceph Manager https://docs.ceph.com/docs/{ceph_codename}/mgr/] daemon is +required. + +[[pveceph_create_mgr]] +Create Manager +~~~~~~~~~~~~~~ + +Multiple Managers can be installed, but at any time only one Manager is active. -The Manager daemon runs alongside the monitors, providing an interface for -monitoring the cluster. Since the Ceph luminous release the -ceph-mgr footnote:[Ceph Manager http://docs.ceph.com/docs/luminous/mgr/] daemon -is required. During monitor installation the ceph manager will be installed as -well. +[source,bash] +---- +pveceph mgr create +---- NOTE: It is recommended to install the Ceph Manager on the monitor nodes. For high availability install more then one manager. + +[[pveceph_destroy_mgr]] +Destroy Manager +~~~~~~~~~~~~~~~ + +To remove a Ceph Manager via the GUI first select a node in the tree view and +go to the **Ceph -> Monitor** panel. Select the Manager and click the +**Destroy** button. + +To remove a Ceph Monitor via the CLI first connect to the node on which the +Manager is running. Then execute the following command: [source,bash] ---- -pveceph createmgr +pveceph mgr destroy ---- +NOTE: A Ceph cluster can function without a Manager, but certain functions like +the cluster status or usage require a running Manager. + [[pve_ceph_osds]] -Creating Ceph OSDs ------------------- +Ceph OSDs +--------- +Ceph **O**bject **S**torage **D**aemons are storing objects for Ceph over the +network. It is recommended to use one OSD per physical disk. + +NOTE: By default an object is 4 MiB in size. + +[[pve_ceph_osd_create]] +Create OSDs +~~~~~~~~~~~ [thumbnail="screenshot/gui-ceph-osd-status.png"] @@ -183,109 +345,114 @@ via GUI or via CLI as follows: [source,bash] ---- -pveceph createosd /dev/sd[X] +pveceph osd create /dev/sd[X] ---- -TIP: We recommend a Ceph cluster size, starting with 12 OSDs, distributed evenly -among your, at least three nodes (4 OSDs on each node). +TIP: We recommend a Ceph cluster size, starting with 12 OSDs, distributed +evenly 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 -~~~~~~~~~~~~~~ +.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. +footnote:[Ceph Bluestore https://ceph.com/community/new-luminous-bluestore/]. +This is the default when creating OSDs since Ceph Luminous. [source,bash] ---- -pveceph createosd /dev/sd[X] +pveceph osd create /dev/sd[X] ---- -NOTE: In order to select a disk in the GUI, to be more fail-safe, 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 -specified separately. +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 osd create /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' +parameters 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 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 -an NVMe SSD or similar. +.Ceph Filestore + +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/sd[X] -bluestore 0 +ceph-volume lvm create --filestore --data /dev/sd[X] --journal /dev/sd[Y] ---- -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. +[[pve_ceph_osd_destroy]] +Destroy OSDs +~~~~~~~~~~~~ -If you want to use a dedicated SSD journal disk: +To remove an OSD via the GUI first select a {PVE} node in the tree view and go +to the **Ceph -> OSD** panel. Select the OSD to destroy. Next click the **OUT** +button. Once the OSD status changed from `in` to `out` click the **STOP** +button. As soon as the status changed from `up` to `down` select **Destroy** +from the `More` drop-down menu. +To remove an OSD via the CLI run the following commands. [source,bash] ---- -pveceph createosd /dev/sd[X] -journal_dev /dev/sd[Y] -bluestore 0 +ceph osd out +systemctl stop ceph-osd@.service ---- +NOTE: The first command instructs Ceph not to include the OSD in the data +distribution. The second command stops the OSD service. Until this time, no +data is lost. -Example: Use /dev/sdf as data disk (4TB) and /dev/sdb is the dedicated SSD -journal disk. - +The following command destroys the OSD. Specify the '-cleanup' option to +additionally destroy the partition table. [source,bash] ---- -pveceph createosd /dev/sdf -journal_dev /dev/sdb -bluestore 0 +pveceph osd destroy ---- +WARNING: The above command will destroy data on the disk! -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]] +Ceph Pools +---------- +A pool is a logical group for storing objects. It holds **P**lacement +**G**roups (`PG`, `pg_num`), a collection of objects. -[[pve_ceph_pools]] -Creating Ceph Pools -------------------- +Create Pools +~~~~~~~~~~~~ [thumbnail="screenshot/gui-ceph-pools.png"] -A pool is a logical group for storing objects. It holds **P**lacement -**G**roups (`PG`, `pg_num`), a collection of objects. - 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. @@ -295,7 +462,7 @@ NOTE: The default number of PGs works for 2-5 disks. Ceph throws a 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://ceph.com/pgcalc/] online. While PGs can be increased later on, they can +https://ceph.com/pgcalc/] online. While PGs can be increased later on, they can never be decreased. @@ -304,18 +471,37 @@ You can create pools through command line or on the GUI on each PVE host under [source,bash] ---- -pveceph createpool +pveceph pool create ---- -If you would like to automatically get also a storage definition for your pool, -active the checkbox "Add storages" on the GUI or use the command line option -'--add_storages' on pool creation. +If you would like to automatically also get a storage definition for your pool, +mark the checkbox "Add storages" in the GUI or use the command line option +'--add_storages' at pool creation. Further information on Ceph pool handling can be found in the Ceph pool operation footnote:[Ceph pool operation -http://docs.ceph.com/docs/luminous/rados/operations/pools/] +https://docs.ceph.com/docs/{ceph_codename}/rados/operations/pools/] manual. + +Destroy Pools +~~~~~~~~~~~~~ + +To destroy a pool via the GUI select a node in the tree view and go to the +**Ceph -> Pools** panel. Select the pool to destroy and click the **Destroy** +button. To confirm the destruction of the pool you need to enter the pool name. + +Run the following command to destroy a pool. Specify the '-remove_storages' to +also remove the associated storage. +[source,bash] +---- +pveceph pool destroy +---- + +NOTE: Deleting the data of a pool is a background task and can take some time. +You will notice that the data usage in the cluster is decreasing. + +[[pve_ceph_device_classes]] Ceph CRUSH & device classes --------------------------- The foundation of Ceph is its algorithm, **C**ontrolled **R**eplication @@ -327,7 +513,7 @@ advantage that no central index service is needed. CRUSH works with a map of OSDs, buckets (device locations) and rulesets (data replication) for pools. NOTE: Further information can be found in the Ceph documentation, under the -section CRUSH map footnote:[CRUSH map http://docs.ceph.com/docs/luminous/rados/operations/crush-map/]. +section CRUSH map footnote:[CRUSH map https://docs.ceph.com/docs/{ceph_codename}/rados/operations/crush-map/]. This map can be altered to reflect different replication hierarchies. The object replicas can be separated (eg. failure domains), while maintaining the desired @@ -390,8 +576,8 @@ ceph osd pool set crush_rule ---- TIP: If the pool already contains objects, all of these have to be moved -accordingly. Depending on your setup this may introduce a big performance hit on -your cluster. As an alternative, you can create a new pool and move disks +accordingly. Depending on your setup this may introduce a big performance hit +on your cluster. As an alternative, you can create a new pool and move disks separately. @@ -404,7 +590,7 @@ 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 section xref:ceph_rados_block_devices[Ceph RADOS Block Devices (RBD)]). -You also need to copy the keyring to a predefined location for a external Ceph +You also need to copy the keyring to a predefined location for an external Ceph cluster. If Ceph is installed on the Proxmox nodes itself, then this will be done automatically. @@ -432,7 +618,9 @@ 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]) +[thumbnail="screenshot/gui-node-ceph-cephfs-panel.png"] + +{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. @@ -465,18 +653,17 @@ 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 -^^^^^^^^^^^^^^^^^^^ +.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/] +daemons https://docs.ceph.com/docs/{ceph_codename}/cephfs/multimds/] [[pveceph_fs_create]] -Create a CephFS -~~~~~~~~~~~~~~~ +Create 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 @@ -504,7 +691,7 @@ This creates a CephFS named `'cephfs'' using a pool for its data named 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/]. +https://docs.ceph.com/docs/{ceph_codename}/rados/operations/placement-groups/]. Additionally, the `'--add-storage'' parameter will add the CephFS to the {pve} storage configuration after it was created successfully. @@ -515,7 +702,7 @@ 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 +destroy, all metadata servers (`M̀DS`). You can destroy them either over the Web GUI or the command line interface, with: ---- @@ -537,6 +724,67 @@ pveceph pool destroy NAME ---- +Ceph maintenance +---------------- + +Replace OSDs +~~~~~~~~~~~~ + +One of the common maintenance tasks in Ceph is to replace a disk of an OSD. If +a disk is already in a failed state, then you can go ahead and run through the +steps in xref:pve_ceph_osd_destroy[Destroy OSDs]. Ceph will recreate those +copies on the remaining OSDs if possible. This rebalancing will start as soon +as an OSD failure is detected or an OSD was actively stopped. + +NOTE: With the default size/min_size (3/2) of a pool, recovery only starts when +`size + 1` nodes are available. The reason for this is that the Ceph object +balancer xref:pve_ceph_device_classes[CRUSH] defaults to a full node as +`failure domain'. + +To replace a still functioning disk, on the GUI go through the steps in +xref:pve_ceph_osd_destroy[Destroy OSDs]. The only addition is to wait until +the cluster shows 'HEALTH_OK' before stopping the OSD to destroy it. + +On the command line use the following commands. +---- +ceph osd out osd. +---- + +You can check with the command below if the OSD can be safely removed. +---- +ceph osd safe-to-destroy osd. +---- + +Once the above check tells you that it is save to remove the OSD, you can +continue with following commands. +---- +systemctl stop ceph-osd@.service +pveceph osd destroy +---- + +Replace the old disk with the new one and use the same procedure as described +in xref:pve_ceph_osd_create[Create OSDs]. + +Trim/Discard +~~~~~~~~~~~~ +It is a good measure to run 'fstrim' (discard) regularly on VMs or containers. +This releases data blocks that the filesystem isn’t using anymore. It reduces +data usage and resource load. Most modern operating systems issue such discard +commands to their disks regularly. You only need to ensure that the Virtual +Machines enable the xref:qm_hard_disk_discard[disk discard option]. + +[[pveceph_scrub]] +Scrub & Deep Scrub +~~~~~~~~~~~~~~~~~~ +Ceph ensures data integrity by 'scrubbing' placement groups. Ceph checks every +object in a PG for its health. There are two forms of Scrubbing, daily +cheap metadata checks and weekly deep data checks. The weekly deep scrub reads +the objects and uses checksums to ensure data integrity. If a running scrub +interferes with business (performance) needs, you can adjust the time when +scrubs footnote:[Ceph scrubbing https://docs.ceph.com/docs/{ceph_codename}/rados/configuration/osd-config-ref/#scrubbing] +are executed. + + Ceph monitoring and troubleshooting ----------------------------------- A good start is to continuosly monitor the ceph health from the start of @@ -546,7 +794,7 @@ 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. +below will also give you an overview of the current events and actions to take. ---- # single time output @@ -557,11 +805,11 @@ 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/]. +adjusted footnote:[Ceph log and debugging https://docs.ceph.com/docs/{ceph_codename}/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. +footnote:[Ceph troubleshooting https://docs.ceph.com/docs/{ceph_codename}/rados/troubleshooting/] +a Ceph cluster on the official website. ifdef::manvolnum[]