On Tue, Oct 16, 2018 at 12:02:32PM +0200, Jan Fajerski wrote:
On Mon, Oct 15, 2018 at 06:56:09AM -0500, Alfredo Deza wrote:
On Mon, Oct 15, 2018 at 6:48 AM Jan Fajerski <jfajerski@xxxxxxxx> wrote:
Hi list,
while playing with ceph-volume I noticed that it adds the tag ceph.data_device
to an lv with the name of the lv (at the time of calling prepare).
I was wondering what this specific tag is used for. From looking at
ceph-volume's code it seems its only ever set.
Using vgrename of lvrename one can easily create an inconsistency in this
self-reference. Restarting the OSD (or rebooting the node) still works as
expected but I'm certainly not thinking of all cases here.
The tags are used as a key/value store in the device, and we try to
add as much info there as possible. I think you are right that
we only set it (for now), but I can see how this could get us into
trouble if we ever depended on it.
A similar issue happens with the ephemeral names of other non-lv
devices, in which case we do update them.
If this doesn't serve a specific purpose I think we shouldn't set the tag (happy
to push a PR).
I think the right thing to do would be to make sure that we have the
right LV and update it if that changes. This would help commands like
`ceph-volume lvm list` which
displays that information.
Would it make sense to change the implementation to simply return the
lv name on the fly instead of duplicating the information in an lvm
tag and trying to keep it consistent?
To specify: I was talking about lv's used for data partitions. I realize that
this tag is also set for journal lv's. I'm sure we could also resolve this on
the fly using the uuid's with a bit more effort.
At least lets add a warning to the documentation for now to not use
[lv,vg]rename on any ceph lv's.
Best,
Jan
--
Jan Fajerski
Engineer Enterprise Storage
SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton,
HRB 21284 (AG Nürnberg)
--
Jan Fajerski
Engineer Enterprise Storage
SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton,
HRB 21284 (AG Nürnberg)
--
Jan Fajerski
Engineer Enterprise Storage
SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton,
HRB 21284 (AG Nürnberg)
