[Gluster-users] Where does Gluster capture the hostnames from?

[Strahil]

Hi Tom,

Your test with dig is wrong - dig and nslookup always query a DNS server.

Maybe 'host' command can show it.

I'm using /etc/hosts only for critical systems - like any kind of clusters as based on my experience - you never know when your DNS will be unreachable (in my case it was a network issue, not a DNS actually).

Of course , a local (same subnet) DNS caching/forwarding server can help and provide offloading for the DNS servers.

Also, I prefer to set all cluster memebers in ntp/chrony's config as peers - because even if your time servers are down , the cluster will stay in sync which is very important.

Have you tried setting an entry like this:

IP FQDN hostname

Then 'hostname' will show something like 'mdskvm-p01' instead of FQDN.

Best Regards,
Strahil Nikolov
On Sep 24, 2019 04:31, TomK wrote: > > Hey All, > > My hosts below: > > [root at mdskvm-p01 ~]# cat /etc/hosts > 127.0.0.1   localhost localhost.localdomain localhost4 > localhost4.localdomain4 > ::1         localhost localhost.localdomain localhost6 > localhost6.localdomain6 > [root at mdskvm-p01 ~]# hostname > mdskvm-p01.nix.mds.xyz > [root at mdskvm-p01 ~]# hostname -f > mdskvm-p01.nix.mds.xyz > [root at mdskvm-p01 ~]# > > [root at mdskvm-p02 ~]# cat /etc/hosts > 127.0.0.1   localhost localhost.localdomain localhost4 > localhost4.localdomain4 > ::1         localhost localhost.localdomain localhost6 > localhost6.localdomain6 > [root at mdskvm-p02 ~]# hostname > mdskvm-p02.nix.mds.xyz > [root at mdskvm-p02 ~]# hostname -f > mdskvm-p02.nix.mds.xyz > [root at mdskvm-p02 ~]# > > My take on the /etc/hosts file discussion: > > 1) If hostname / hostname -f returns any valid values, the software > should capture it. > > 2) There is no benefit or need to use /etc/hosts in a small setup. > Larger setups resolving hosts against an enterprise DNS behind many > switches could be a problem.  Managing our /etc/hosts files using > Ansible helped to reduce some of these problems esp since lookups are > logged against the connection tracking tables, that can get full, > network response time could vary etc.  ("Semi static" I guess might > describe this approach best?)  These are populated, if changes are > needed, via an initial DNS lookup once a day. Invariably, managing > /etc/hosts is time consuming and messy. > > 3) Running a good DNS cluster, something like a two node IPA cluster > that I run for a small setup, prevents such outages.  This particularly > when also placing a VIP across the nodes and locating cluster nodes > across different hardware and locations. > > 4) Point 2) should be no reason why an application cannot obtain or > resolve proper DNS entries in 1). > > Having said that, decided to check if there's any benefit to having > entries in /etc/hosts: > > [root at mdskvm-p01 ~]# time $(dig  mdskvm-p01.nix.mds.xyz >/dev/null) > > real    0m0.092s > user    0m0.087s > sys     0m0.005s > [root at mdskvm-p01 ~]# time $(dig  mdskvm-p02.nix.mds.xyz >/dev/null) > > real    0m0.092s > user    0m0.084s > sys     0m0.008s > [root at mdskvm-p01 ~]# cat /etc/hosts > 127.0.0.1   localhost localhost.localdomain localhost4 > localhost4.localdomain4 > ::1         localhost localhost.localdomain localhost6 > localhost6.localdomain6 > 192.168.0.60    mdskvm-p01.nix.mds.xyz  mdskvm-p01 > 192.168.0.39    mdskvm-p02.nix.mds.xyz  mdskvm-p02 > [root at mdskvm-p01 ~]# vi /etc/hosts > [root at mdskvm-p01 ~]# time $(dig  mdskvm-p01.nix.mds.xyz >/dev/null) > > real    0m0.093s > user    0m0.082s > sys     0m0.010s > [root at mdskvm-p01 ~]# time $(dig  mdskvm-p02.nix.mds.xyz >/dev/null) > > real    0m0.093s > user    0m0.085s > sys     0m0.007s > [root at mdskvm-p01 ~]# time $(dig  mdskvm-p01.nix.mds.xyz >/dev/null) > > real    0m0.094s > user    0m0.084s > sys     0m0.010s > [root at mdskvm-p01 ~]# time $(dig  mdskvm-p02.nix.mds.xyz >/dev/null) > > real    0m0.092s > user    0m0.081s > sys     0m0.011s > [root at mdskvm-p01 ~]# cat /etc/hosts > 127.0.0.1   localhost localhost.localdomain localhost4 > localhost4.localdomain4 > ::1         localhost localhost.localdomain localhost6 > localhost6.localdomain6 > [root at mdskvm-p01 ~]# > > So with /etc/hosts file entries present makes little difference in small > setup when governed by /etc/nsswitch.conf . > > Having entries in /etc/hosts, doesn't affect how gluster displays the > entries when calling gluster volume status . > > Cheers, > TK > > On 9/23/2019 11:36 AM, Joe Julian wrote: > > Perhaps I misread the intent, I apologize if I did. I read "static > > entries" as "ip addresses" which I've seen suggested (from my > > perspective) far too often. /etc/hosts is a valid solution that can > > still adapt if the network needs to evolve. > > > > On 9/23/19 8:29 AM, ROUVRAIS Cedric wrote: > >> Hello, > >> > >> I gue
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