Hi,
perhaps an stupid question, but why you change the hostname?
Not tried, but I guess if you boot the node with an new hostname,
the old hostname are in the crush map, but without any OSDs -
because they are on the new host.
Don't know ( I guess not) if the degration level stay also on 5% if
you delete the empty host from the crush map.
I would simply use the same hostconfig on an rebuildet host.
Udo
On 03.12.2014 05:06, Indra Pramana
wrote:
Dear all,
We have a Ceph cluster with several nodes, each node
contains 4-6 OSDs. We are running the OS off USB drive
to maximise the use of the drive bays for the OSDs and
so far everything is running fine.
Occasionally, the OS running on the USB drive would fail,
and we would normally replace the drive with a
pre-configured similar OS and Ceph running, so when the
new OS boots up, it will automatically detect all the OSDs
and start them. It works fine without any issues.
However, the issue is in recovery. When one node goes down,
all the OSDs would be down and recovery will start to move
the pg replicas on the affected OSDs to other available
OSDs, and cause the Ceph to be degraded, say 5%, which is
expected. However, when we boot up the failed node with a
new OS, and bring back the OSDs up, more PGs are being
scheduled for backfilling and instead of reducing, the
degradation level will shoot up again to, for example, 10%,
and in some occasion, it goes up to 19%.
We had experience when one node is down, it will degraded to
5% and recovery will start, but when we manage to bring back
up the node (still the same OS), the degradation level will
reduce to below 1% and eventually recovery will be completed
faster.
Why the same behaviour doesn't apply on the above situation?
The OSD numbers are the same when the node boots up, the crush
map weight values are also the same. Only the hostname is
different.
Any advice / suggestions?
Looking forward to your reply, thank you.
Cheers.
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