-----------
endif::manvolnum[]
ifndef::manvolnum[]
-Manage Ceph Services on Proxmox VE Nodes
-========================================
+Deploy Hyper-Converged Ceph Cluster
+===================================
:pve-toplevel:
endif::manvolnum[]
.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.
+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
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
+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.
footnote:[Ceph Manager https://docs.ceph.com/docs/{ceph_codename}/mgr/] daemon is
required.
-[i[pveceph_create_mgr]]
+[[pveceph_create_mgr]]
Create Manager
~~~~~~~~~~~~~~
----
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)
+parameters respectively. If they are not given the following values (in order)
will be used:
* bluestore_block_{db,wal}_size from ceph configuration...
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.
+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
Replace the old disk with the new one and use the same procedure as described
in xref:pve_ceph_osd_create[Create OSDs].
-NOTE: With the default size/min_size (3/2) of a pool, recovery only starts when
-`size + 1` nodes are available.
-
-Run fstrim (discard)
-~~~~~~~~~~~~~~~~~~~~
+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 the resource load.
+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
-(metadata compare) and weekly. The weekly reads the objects and uses checksums
-to ensure data integrity. If a running scrub interferes with business needs,
-you can adjust the time when scrubs footnote:[Ceph scrubbing
-https://docs.ceph.com/docs/{ceph_codename}/rados/configuration/osd-config-ref/#scrubbing]
+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.
projects / pve-docs.git / blobdiff