I've reinstalled a host many times over the years. We used dmcrypt so I made sure to back up the keys for that. Other than that it is seamless as long as your installation process only affects the root disk. If it affected any osd or journal disk, then you would need to mark those osds out and re-add them to the cluster.
On Wed, Sep 27, 2017, 4:33 AM Ronny Aasen <ronny+ceph-users@xxxxxxxx> wrote:
On 27. sep. 2017 10:09, Pierre Palussiere wrote:
> Hi,
>
> Is anyone know if it’s possible to re install ceph on a host and keep osd without wipe data on them ?
>
> Hope you can help me,
it depends... if you have journal on same drive as osd, you should be
able to eject the drive from a server, connect it to another and udev
should mount and active osd (data will ofcourse move)
i can not see why reinstall of a host would be much different from
moving the disk.
if you have journal on a separate device then you need to move osd and
journal device together. you can also have configuration that makes this
process less automatic.
!BUT! i would not in any way risk reinstalling a host with live osd's.!
I would set all osd's out and let the data remap to other osd's so you
have a temporary replica on other osd's. while reinstalling. the
backfill should be fast since the data is still on disk.
or
I would set crush weight to 0 and drain all osd's off the node before
reinstalling. here the backfill will take longer, since you actualy have
to refill disks.
kind regards
Ronny Aasen
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