====== Move DB to bigger storage ======

I.e: to move from 4GB partition to 30GB partition in case of spillover:

<code>
1 OSD(s) experiencing BlueFS spillover

 osd.3 spilled over 985 MiB metadata from 'db' device (3.8 GiB used of 4.0 GiB) to slow device
</code>


<code>
lvdisplay
  --- Logical volume ---
  LV Path                /dev/ceph-66ad9fa6-0f65-4fc0-baeb-41089a509347/osd-block-4a9e142e-ed4d-4890-a018-5651c36071a5
  LV Name                osd-block-4a9e142e-ed4d-4890-a018-5651c36071a5

  --- Logical volume ---
  LV Path                /dev/ceph-ffd9911c-2d6c-43aa-b637-bec8a2092a30/osd-db-ad0a2108-bcca-4f15-9747-29d86624b911
  LV Name                osd-db-ad0a2108-bcca-4f15-9747-29d86624b911
  VG Name                ceph-ffd9911c-2d6c-43aa-b637-bec8a2092a30

  LV Size                4,00 GiB
  Current LE             1024
  
vgdisplay
    --- Volume group ---
  VG Name               ceph-ffd9911c-2d6c-43aa-b637-bec8a2092a30
  VG Size               4,00 GiB
  PE Size               4,00 MiB
  Total PE              1025
  Alloc PE / Size       1024 / 4,00 GiB
  Free  PE / Size       1 / 4,00 MiB

pvdisplay  
  --- Physical volume ---
  PV Name               /dev/nvme0n1p5
  VG Name               ceph-ffd9911c-2d6c-43aa-b637-bec8a2092a30
  PV Size               <4,01 GiB / not usable 2,00 MiB
  Allocatable           yes 
  PE Size               4,00 MiB
  Total PE              1025
  Free PE               1
  Allocated PE          1024
  PV UUID               pjYGgY-SS26-m8Sc-aWyQ-3zzY-f7Iz-XGoI90
</code>

===== resize exsiting DB partition =====

Remove separate DB and migrate data back to main storage:
<code bash>
ceph osd set noout
systemctl stop ceph-osd@3.service

cat /var/lib/ceph/osd/ceph-3/fsid 
lvdisplay

ceph-volume lvm migrate --osd-id 3 --osd-fsid 024c05b3-6e22-4df1-b0af-5cb46725c5c8 --from db --target ceph-5582d170-f77e-495c-93c6-791d9310872c/osd-block-024c05b3-6e22-4df1-b0af-5cb46725c5c8
--> Migrate to existing, Source: ['--devs-source', '/var/lib/ceph/osd/ceph-0/block.db'] Target: /var/lib/ceph/osd/ceph-0/block
--> Migration successful.
</code>

Create new PV,VG,LV for DB and attach it:

<code bash>
pvcreate /dev/nvme0n1p6
vgcreate ceph-db-8gb /dev/nvme0n1p6
lvcreate -n db-8gb -l 100%FREE ceph-db-8gb

ceph-volume lvm new-db --osd-id 0 --osd-fsid 024c05b3-6e22-4df1-b0af-5cb46725c5c8 --target ceph-db-8gb/db-8gb
--> Making new volume at /dev/ceph-db-8gb/db-8gb for OSD: 0 (/var/lib/ceph/osd/ceph-0)
Running command: /usr/bin/chown -h ceph:ceph /var/lib/ceph/osd/ceph-0/block.db
Running command: /usr/bin/chown -R ceph:ceph /dev/dm-0
--> New volume attached.
</code>

<code bash>
ceph-volume lvm migrate --osd-id 0 --osd-fsid 024c05b3-6e22-4df1-b0af-5cb46725c5c8 --from data db --target ceph-db-8gb/db-8gb
--> Migrate to existing, Source: ['--devs-source', '/var/lib/ceph/osd/ceph-0/block'] Target: /var/lib/ceph/osd/ceph-0/block.db
--> Migration successful.
</code>

<code bash>
systemctl start ceph-osd@3.service
ceph osd unset noout
</code>

===== OR: create new one =====


Create new 41GB (41984MB) partition (/dev/nvme0n1p6)
<code>
pvcreate /dev/nvme0n1p6
vgcreate ceph-db-40gb /dev/nvme0n1p6
lvcreate -n db-40gb -l 100%FREE ceph-db-40gb
</code>

<code bash>
ceph osd set noout
systemctl stop ceph-osd@3.service

cat /var/lib/ceph/osd/ceph-3/fsid 

ceph-volume lvm migrate --osd-id 3 --osd-fsid 4a9e142e-ed4d-4890-a018-5651c36071a5 --from db --target ceph-db-40gb/db-40gb

systemctl start ceph-osd@3.service
ceph osd unset noout
</code>

====== Move DB disks ======

In case of replace (full copy by ''dd'') NVM drive where partition for OSD's DB is located, OSD service cannot start.
Reason is that CEPH doesn't have permission to access device owned by ''root''. To repair everything with one command:
<code bash>
ceph-volume lvm activate --all
</code>



====== draft ======
<code>
$ systemctl stop ceph-osd@68
$ ceph-bluestore-tool --path /var/lib/ceph/osd/ceph-68 --devs-source
/var/lib/ceph/osd/ceph-68/block --dev-target
/var/lib/ceph/osd/ceph-68/block.db  bluefs-bdev-migrate
$ systemctl start ceph-osd@68
</code>