[ceph-users] Filestore to Bluestore migration question

Hector Martin hector at marcansoft.com
Wed Nov 7 09:21:29 PST 2018

On 11/8/18 2:15 AM, Hayashida, Mami wrote:
> Thank you very much.  Yes, I am aware that zapping the SSD and
> converting it to LVM requires stopping all the FileStore OSDs whose
> journals are on that SSD first.  I will add in the `hdparm` to my steps.
> I did run into remnants of gpt information lurking around when trying to
> re-use osd disks in the past -- so that's probably a good preemptive move.

Just for reference, "ceph-volume lvm zap" runs wipefs and also wipes the
beginning of the device separately. It should get rid of the GPT
partition table. hdparm -z just tells the kernel to re-read it (which
should remove any device nodes associated with now-gone partitions).

I just checked the wipefs manpage and it seems it does trigger a
partition table re-read itself, which would make the hdparm unnecessary.
It might be useful if you can check that the partition devices (sda1
etc) exist before the zap command and disappear after it, confirming
that hdparm is not necessary. And if they still exist, then run hdparm,
and if they persist after that too, something's wrong and you should
investigate. GPT partition tables can be notoriously annoying to wipe
because there is a backup at the end of the device, but wipefs *should*
know about that as far as I know.

Hector Martin (hector at marcansoft.com)
Public Key: https://mrcn.st/pub

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