# managing ceph

Always refer back to the official documentation at https://docs.ceph.com/en/latest

## adding new cephfs
- create a erasure code profile which will allow you to customise the raid level
    - raid5 with 3 disks? k=2,m=1
    - raid5 with 6 disks? k=5,m=1
    - raid6 with 4 disks? k=2,m=2, etc
- create osd pool using custom profile for data
- create osd pool using default replicated profile for metadata
- enable ec_overwrites for the data pool
- create the ceph fs volume using data/metadata pools
- set ceph fs settings
    - specify minimum number of metadata servers (mds)
    - set fs to be for bulk data
    - set mds fast failover with standby reply


```
    sudo ceph osd erasure-code-profile set ec_4_1 k=4 m=1
    sudo ceph osd pool create media_data 128 erasure ec_4_1
    sudo ceph osd pool create media_metadata 32 replicated_rule
    sudo ceph osd pool set media_data allow_ec_overwrites true
    sudo ceph osd pool set media_data bulk true
    sudo ceph fs new mediafs media_metadata media_data --force
    sudo ceph fs set mediafs allow_standby_replay true
    sudo ceph fs set mediafs max_mds 2
```


## managing cephfs with subvolumes

This will:

-- Create erasure code profiles. The K and M values are equivalent to the number of data disks (K) and parity disks (M) in RAID5, RAID6, etc.
-- Create data pools using the erasure-code-profile, set some required options
-- Add the pool to the fs `cephfs`
-- Create a subvolumegroup using the new data pool


    sudo ceph osd erasure-code-profile set ec_6_2 k=6 m=2
    sudo ceph osd pool create cephfs_data_ssd_ec_6_2 erasure ec_6_2
    sudo ceph osd pool set cephfs_data_ssd_ec_6_2 allow_ec_overwrites true
    sudo ceph osd pool set cephfs_data_ssd_ec_6_2 bulk true
    sudo ceph fs add_data_pool cephfs cephfs_data_ssd_ec_6_2
    sudo ceph fs subvolumegroup create cephfs csi_ssd_ec_6_2 --pool_layout cephfs_data_ssd_ec_6_2

    sudo ceph osd erasure-code-profile set ec_4_1 k=4 m=1
    sudo ceph osd pool create cephfs_data_ssd_ec_4_1 erasure ec_4_1
    sudo ceph osd pool set cephfs_data_ssd_ec_4_1 allow_ec_overwrites true
    sudo ceph osd pool set cephfs_data_ssd_ec_4_1 bulk true
    sudo ceph fs add_data_pool cephfs cephfs_data_ssd_ec_4_1
    sudo ceph fs subvolumegroup create cephfs csi_ssd_ec_4_1 --pool_layout cephfs_data_ssd_ec_4_1

Create a key with access to the new subvolume groups. Check if the user already exists first:

    sudo ceph auth get client.kubernetes-cephfs

If it doesnt:

sudo ceph auth get-or-create client.kubernetes-cephfs \
  mgr 'allow rw' \
  osd 'allow rw tag cephfs metadata=cephfs, allow rw tag cephfs data=cephfs' \
  mds 'allow r fsname=cephfs path=/volumes, allow rws fsname=cephfs path=/volumes/csi_ssd_ec_6_2, allow rws fsname=cephfs path=/volumes/csi_ssd_ec_4_1' \
  mon 'allow r fsname=cephfs'

If it does, use `sudo ceph auth caps client.kubernetes-cephfs ...` instead to update existing capabilities.

## removing a cephfs subvolumegroup from cephfs

This will cleanup the subvolumegroup, and subvolumes if they exist, then remove the pool.

Check for subvolumegroups first, then for subvolumes in it

    sudo ceph fs subvolumegroup ls cephfs
    sudo ceph fs subvolume ls cephfs --group_name csi_raid6


If subvolumes exist, remove each one-by-one:

    sudo ceph fs subvolume rm cephfs <subvol_name> --group_name csi_raid6

If you have snapshots, remove snapshots first:

    sudo ceph fs subvolume snapshot ls cephfs <subvol_name> --group_name csi_raid6
    sudo ceph fs subvolume snapshot rm cephfs <subvol_name> <snap_name> --group_name csi_raid6

Once the group is empty, remove it:

    sudo ceph fs subvolumegroup rm cephfs csi_raid6

If it complains it’s not empty, go back as there’s still a subvolume or snapshot.

If you added it with `ceph fs add_data_pool`. Undo with `rm_data_pool`:

    sudo ceph fs rm_data_pool cephfs cephfs_data_csi_raid6

After it’s detached from CephFS, you can delete it.

    sudo ceph osd pool rm cephfs_data_csi_raid6 cephfs_data_csi_raid6 --yes-i-really-really-mean-it


## creating authentication tokens

- this will create a client keyring named media
- this client will have the following capabilities:
    - mon: read
    - mds:
        - read /
        - read/write /media
        - read/write /common
    - osd: read/write to cephfs_data pool

```
    sudo ceph auth get-or-create client.media \
      mon 'allow r' \
      mds 'allow r path=/, allow rw path=/media, allow rw path=/common' \
      osd 'allow rw pool=cephfs_data'
```

## list the authentication tokens and permissions

    ceph auth ls

## change the capabilities of a token

this will overwrite the current capabilities of a given client.user

    sudo ceph auth caps client.media \
      mon 'allow r' \
      mds 'allow rw path=/' \
      osd 'allow rw pool=media_data'

## adding a new osd on new node

create the ceph conf (automate this?)

    cat <<EOF | sudo tee /etc/ceph/ceph.conf
    [global]
      auth_client_required = cephx
      auth_cluster_required = cephx
      auth_service_required = cephx
      fsid = de96a98f-3d23-465a-a899-86d3d67edab8
      mon_allow_pool_delete = true
      mon_initial_members = prodnxsr0009,prodnxsr0010,prodnxsr0011,prodnxsr0012,prodnxsr0013
      mon_host = 198.18.23.9,198.18.23.10,198.18.23.11,198.18.23.12,198.18.23.13
      ms_bind_ipv4 = true
      ms_bind_ipv6 = false
      osd_crush_chooseleaf_type = 1
      osd_pool_default_min_size = 2
      osd_pool_default_size = 3
      osd_pool_default_pg_num = 128
      public_network = 198.18.23.1/32,198.18.23.2/32,198.18.23.3/32,198.18.23.4/32,198.18.23.5/32,198.18.23.6/32,198.18.23.7/32,198.18.23.8/32,198.18.23.9/32,198.18.23.10/32,198.18.23.11/32,198.18.23.12/32,198.18.23.13/32
    EOF

ssh to one of the monitor hosts, then transfer the keys required

    sudo cat /etc/ceph/ceph.client.admin.keyring | ssh prodnxsr0003 'sudo tee /etc/ceph/ceph.client.admin.keyring'
    sudo cat /var/lib/ceph/bootstrap-osd/ceph.keyring | ssh prodnxsr0003 'sudo tee /var/lib/ceph/bootstrap-osd/ceph.keyring'

assuming we are adding /dev/sda to the cluster, first zap the disk to remove partitions/lvm/metadata

    sudo ceph-volume lvm zap /dev/sda --destroy

then add it to the cluster

    sudo ceph-volume lvm create --data /dev/sda

## removing an osd

check what OSD IDs were on this host (if you know it)

    sudo ceph osd tree

or check for any DOWN osds

    sudo ceph osd stat
    sudo ceph health detail

once you identify the old OSD ID, remove it with these steps, replace X with the actual OSD ID:

    sudo ceph osd out osd.X
    sudo ceph osd down osd.X
    sudo ceph osd crush remove osd.X
    sudo ceph auth del osd.X
    sudo ceph osd rm osd.X


## maintenance mode for the cluster

from one node in the cluster disable recovery

    sudo ceph osd set noout
    sudo ceph osd set nobackfill
    sudo ceph osd set norecover
    sudo ceph osd set norebalance
    sudo ceph osd set nodown
    sudo ceph osd set pause

to undo the change, use unset

    sudo ceph osd unset noout
    sudo ceph osd unset nobackfill
    sudo ceph osd unset norecover
    sudo ceph osd unset norebalance
    sudo ceph osd unset nodown
    sudo ceph osd unset pause