mount.cephfs with domain name and multiple ip addresses

mount.cephfs with domain name and multiple ip addresses

[Michael Wyraz]

Hello,

I have multiple ceph monitor nodes and one domain name that has an a
record for each node. I use this record in my fstab, e.g.:

    mon.mycephcluster.com:6789:/ /backups/ ceph _netdev

In /proc/mounts, I can see all IPs for mon.mycephcluster.com, e.g.:

    1.1.1.1:6789,2.2.2.2:6789,2.2.2.2:6789:/ /backups ceph
    rw,relatime,acl 0 0

This works perfect and is a really good thing because it makes
adding/removing nodes much more easy. What I'd like to know is if this
is intended behaviour (in this case it should be documented in the
manpage) or if this could have unexpected side effects.

Kind regards,
Michael.

Re: mount.cephfs with domain name and multiple ip addresses

[wido]

> Op 22 jun. 2016 om 07:56 heeft Michael Wyraz <michael@wyraz.de> het volgende geschreven:
> 
> Hello,
> 
> I have multiple ceph monitor nodes and one domain name that has an a
> record for each node. I use this record in my fstab, e.g.:
> 
>    mon.mycephcluster.com:6789:/ /backups/ ceph _netdev
> 
> In /proc/mounts, I can see all IPs for mon.mycephcluster.com, e.g.:
> 
>    1.1.1.1:6789,2.2.2.2:6789,2.2.2.2:6789:/ /backups ceph
>    rw,relatime,acl 0 0
> 
> This works perfect and is a really good thing because it makes
> adding/removing nodes much more easy. What I'd like to know is if this
> is intended behaviour (in this case it should be documented in the
> manpage) or if this could have unexpected side effects.
> 

That is the intended behaviour and works as you describe. Nothing weird about this, actually a cool feature of Ceph.

Wido

> Kind regards,
> Michael.
> 
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Re: mount.cephfs with domain name and multiple ip addresses

[Sage Weil]

On Wed, 22 Jun 2016, wido@42on.com wrote:
> > Op 22 jun. 2016 om 07:56 heeft Michael Wyraz <michael@wyraz.de> het volgende geschreven:
> > 
> > Hello,
> > 
> > I have multiple ceph monitor nodes and one domain name that has an a
> > record for each node. I use this record in my fstab, e.g.:
> > 
> >    mon.mycephcluster.com:6789:/ /backups/ ceph _netdev
> > 
> > In /proc/mounts, I can see all IPs for mon.mycephcluster.com, e.g.:
> > 
> >    1.1.1.1:6789,2.2.2.2:6789,2.2.2.2:6789:/ /backups ceph
> >    rw,relatime,acl 0 0
> > 
> > This works perfect and is a really good thing because it makes
> > adding/removing nodes much more easy. What I'd like to know is if this
> > is intended behaviour (in this case it should be documented in the
> > manpage) or if this could have unexpected side effects.
> > 
> 
> That is the intended behaviour and works as you describe. Nothing weird 
> about this, actually a cool feature of Ceph.

Yes.  You can also add multiple A (or AAAA) records to DNS so that your 
fstab line is simple (e.g., mycluster-mons.foo.com) and can be easily 
updated (via DNS) when your mons change.  Same goes for the mon host = ... 
line in ceph.conf.

sage