Hi,
to create a second filesystem you have to use different pools anyway.
If you already have one CephFS up and running then you also should
have at least one standby daemon, right? If you create a new FS and
that standby daemon is not configured to any specific rank then it
will be used for the second filesystem. Now you'll have two active MDS
both with rank 0 (active):
---snip---
ceph:~ # ceph fs status
cephfs - 1 clients
======
+------+--------+-------+---------------+-------+-------+
| Rank | State | MDS | Activity | dns | inos |
+------+--------+-------+---------------+-------+-------+
| 0 | active | host6 | Reqs: 0 /s | 10 | 13 |
+------+--------+-------+---------------+-------+-------+
+-----------------+----------+-------+-------+
| Pool | type | used | avail |
+-----------------+----------+-------+-------+
| cephfs_metadata | metadata | 1536k | 92.0G |
| cephfs_data | data | 5053M | 92.0G |
+-----------------+----------+-------+-------+
cephfs2 - 0 clients
=======
+------+--------+-------+---------------+-------+-------+
| Rank | State | MDS | Activity | dns | inos |
+------+--------+-------+---------------+-------+-------+
| 0 | active | host5 | Reqs: 0 /s | 10 | 13 |
+------+--------+-------+---------------+-------+-------+
+------------------+----------+-------+-------+
| Pool | type | used | avail |
+------------------+----------+-------+-------+
| cephfs2_metadata | metadata | 1536k | 92.0G |
| cephfs2_data | data | 0 | 92.0G |
+------------------+----------+-------+-------+
+-------------+
| Standby MDS |
+-------------+
+-------------+
---snip---
For the standby daemon you have to be aware of this:
By default, if none of these settings are used, all MDS daemons
which do not hold a rank will
be used as 'standbys' for any rank.
[...]
When a daemon has entered the standby replay state, it will only be
used as a standby for
the rank that it is following. If another rank fails, this standby
replay daemon will not be
used as a replacement, even if no other standbys are available.
Some of the mentioned settings are for example:
mds_standby_for_rank
mds_standby_for_name
mds_standby_for_fscid
The easiest way is to have one standby daemon per CephFS and let them
handle the failover.
Regards,
Eugen
Zitat von Jarett DeAngelis <jarett@xxxxxxxxxxxx>:
Hi guys,
This is documented as an experimental feature, but it doesn’t
explain how to ensure that affinity for a given MDS sticks to the
second filesystem you create. Has anyone had success implementing a
second CephFS? In my case it will be based on a completely different
pool from my first one.
Thanks.
J
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