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docs: ceph: explain pool options

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Signed-off-by: Alwin Antreich <a.antreich@proxmox.com>
Originally-by: Alwin Antreich <a.antreich@proxmox.com>
Edited-by: Dylan Whyte <d.whyte@proxmox.com>
Signed-off-by: Dylan Whyte <d.whyte@proxmox.com>
Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
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Dylan Whyte 2021-02-18 11:39:09 +01:00 committed by Thomas Lamprecht
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@ -466,12 +466,16 @@ WARNING: **Do not set a min_size of 1**. A replicated pool with min_size of 1
allows I/O on an object when it has only 1 replica which could lead to data
loss, incomplete PGs or unfound objects.
It is advised to calculate the PG number depending on your setup, you can find
the formula and the PG calculator footnote:[PG calculator
https://ceph.com/pgcalc/] online. From Ceph Nautilus onwards it is possible to
increase and decrease the number of PGs later on footnote:[Placement Groups
{cephdocs-url}/rados/operations/placement-groups/].
It is advised that you calculate the PG number based on your setup. You can
find the formula and the PG calculator footnote:[PG calculator
https://ceph.com/pgcalc/] online. From Ceph Nautilus onward, you can change the
number of PGs footnoteref:[placement_groups,Placement Groups
{cephdocs-url}/rados/operations/placement-groups/] after the setup.
In addition to manual adjustment, the PG autoscaler
footnoteref:[autoscaler,Automated Scaling
{cephdocs-url}/rados/operations/placement-groups/#automated-scaling] can
automatically scale the PG count for a pool in the background.
You can create pools through command line or on the GUI on each PVE host under
**Ceph -> Pools**.
@ -485,6 +489,34 @@ 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.
.Base Options
Name:: The name of the pool. This must be unique and can't be changed afterwards.
Size:: The number of replicas per object. Ceph always tries to have this many
copies of an object. Default: `3`.
PG Autoscale Mode:: The automatic PG scaling mode footnoteref:[autoscaler] of
the pool. If set to `warn`, it produces a warning message when a pool
has a non-optimal PG count. Default: `warn`.
Add as Storage:: Configure a VM or container storage using the new pool.
Default: `true`.
.Advanced Options
Min. Size:: The minimum number of replicas per object. Ceph will reject I/O on
the pool if a PG has less than this many replicas. Default: `2`.
Crush Rule:: The rule to use for mapping object placement in the cluster. These
rules define how data is placed within the cluster. See
xref:pve_ceph_device_classes[Ceph CRUSH & device classes] for information on
device-based rules.
# of PGs:: The number of placement groups footnoteref:[placement_groups] that
the pool should have at the beginning. Default: `128`.
Traget Size:: The estimated amount of data expected in the pool. The PG
autoscaler uses this size to estimate the optimal PG count.
Target Size Ratio:: The ratio of data that is expected in the pool. The PG
autoscaler uses the ratio relative to other ratio sets. It takes precedence
over the `target size` if both are set.
Min. # of PGs:: The minimum number of placement groups. This setting is used to
fine-tune the lower bound of the PG count for that pool. The PG autoscaler
will not merge PGs below this threshold.
Further information on Ceph pool handling can be found in the Ceph pool
operation footnote:[Ceph pool operation
{cephdocs-url}/rados/operations/pools/]
@ -697,10 +729,9 @@ This creates a CephFS named `'cephfs'' using a pool for its data 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
{cephdocs-url}/rados/operations/placement-groups/].
number (`pg_num`) for your setup footnoteref:[placement_groups].
Additionally, the `'--add-storage'' parameter will add the CephFS to the {pve}
storage configuration after it was created successfully.
storage configuration after it has been created successfully.
Destroy CephFS
~~~~~~~~~~~~~~