disks with existing bluestore LVM data will be reformatted without warning unlike filestore

[Trent Lloyd]

If you deploy ceph-osd to a machine whose disks already have bluestore LVM data from a previous install, it will reformat the disk and provision it for the new cluster.

This is not expected, as for filestore it was implemented to specifically require zapping non-clean disks to prevent accidental data loss, such as was experienced with the osd-reformat option.

This doesn't normally happen for the same install, as the charm keeps track of device paths which have been initialized, it's still a concern that the charm will over-write a non-empty disk as there may be bugs or scenarios where that could occur.

= Steps to reproduce =

To reproduce, deploy ceph-osd to a physical machine (MAAS), delete the model (without wiping the disks) and redeploy it.

= Desired behavior =

The charm should only initialize a device if it has no data at all, e.g. no label of any kind.

[nikhil kshirsagar (nkshirsagar)]

This does not appear to be a bug. Have discussed this with Trent.

After deploying an osd using sdb on gardener, lsblk shows,

root@gardener:/var/log/juju# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 3.7T 0 disk
├─sda1 8:1 0 512M 0 part /boot/efi
└─sda2 8:2 0 3.7T 0 part /
sdb 8:16 0 3.7T 0 disk
└─ceph--14427572--ae02--4a5b--89f8--bbb24d1a9155-osd--block--14427572--ae02--4a5b--89f8--bbb24d1a9155 253:0 0 3.7T 0 lvm
sdc 8:32 0 3.7T 0 disk
sdd

Then created a partition on sdc, with a xfs fs on it, (did not bother mounting it)

root@gardener:/var/log/juju# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 3.7T 0 disk
├─sda1 8:1 0 512M 0 part /boot/efi
└─sda2 8:2 0 3.7T 0 part /
sdb 8:16 0 3.7T 0 disk
└─ceph--14427572--ae02--4a5b--89f8--bbb24d1a9155-osd--block--14427572--ae02--4a5b--89f8--bbb24d1a9155 253:0 0 3.7T 0 lvm
sdc 8:32 0 3.7T 0 disk
└─sdc1 <------- 8:33 0 467M 0 part
sdd

Created fs on sdc1. sdc1 partition is offset beyond 10MB of the device.

root@gardener:/var/log/juju# wipefs /dev/sdc
DEVICE OFFSET TYPE UUID LABEL
sdc 0x1fe dos
        ^^^
      10.5M

ubuntu@z-rotomvm33:~$ juju status
Model Controller Cloud/Region Version SLA Timestamp
reproducernikhil segmaas-default segmaas/default 2.9.10 unsupported 09:32:28Z

App Version Status Scale Charm Store Channel Rev OS Message
ceph-mon 15.2.13 active 1 ceph-mon charmstore stable 56 ubuntu Unit is ready and clustered
ceph-osd 15.2.13 active 1 ceph-osd charmstore stable 312 ubuntu Unit is ready (1 OSD)

Unit Workload Agent Machine Public address Ports Message
ceph-mon/1* active idle 2 10.230.57.23 Unit is ready and clustered
ceph-osd/0* active idle 1 10.230.57.22 Unit is rea...