X-Git-Url: https://git.proxmox.com/?p=pve-docs.git;a=blobdiff_plain;f=pveceph.adoc;h=8dc85680ded076094afd9d7afb724f5ccd1761e7;hp=d01ae462d0c49a4b2153de6060fe6259d2efee82;hb=31df4fee0443eb4e00fdf2a6cbfc88c2789f5882;hpb=af6f59f49f55a42b15cc52c49497baf80aed5c0b

diff --git a/pveceph.adoc b/pveceph.adoc
index d01ae46..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[]
 
@@ -86,9 +86,16 @@ 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.
+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
@@ -101,7 +108,7 @@ 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
+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.
 
@@ -286,7 +293,7 @@ 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.
 
-[i[pveceph_create_mgr]]
+[[pveceph_create_mgr]]
 Create Manager
 ~~~~~~~~~~~~~~
 
@@ -378,7 +385,7 @@ 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'
-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...
@@ -758,21 +765,23 @@ pveceph osd destroy <id>
 Replace the old disk with the new one and use the same procedure as described
 in xref:pve_ceph_osd_create[Create OSDs].
 
-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.