Hi All,
I really like the idea of warning users against using unsafe practices.
Wouldn't it make sense to warn against using min_size=1 instead of size=1.
I've seen data loss happen with size=2 min_size=1 when multiple failures
occur and write have been done between the failures. Effectively the new
warning below says "It is not considered safe to run with no
redundancy". Which is true, but when failure occurs or maintenance is
executed, with size=2 and min_size=1, as soon as data is written, there
might not be data redundancy for that newly written data. A failure of
an OSD at that moment would result in data loss.
Since you cannot run size=1 with min_size > 1, this use-case would also
be covered.
I understand this has implications for size=2 when executing
maintenance, but I think most people are not aware of the risks they are
taking with min_size=1. Those that are aware can suppress the warning.
* Ceph will issue a health warning if a RADOS pool's `size` is set to 1
or in other words the pool is configured with no redundancy. This can
be fixed by setting the pool size to the minimum recommended value
with::
ceph osd pool set <pool-name> size <num-replicas>
The warning can be silenced with::
ceph config set global mon_warn_on_pool_no_redundancy false
--
kind regards,
Wout
42on
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