[Gluster-users] Where does Gluster capture the hostnames from?
TomK
tomkcpr at mdevsys.com
Mon Sep 30 03:51:03 UTC 2019
Because this was a LAB I could quickly remove the gluster setup and
recreated it and used the FQDN's, it quickly picked up the new names.
Exactly as expected per this thread.
[root at mdskvm-p02 network-scripts]# gluster volume status
Status of volume: mdsgv01
Gluster process TCP Port RDMA Port Online Pid
------------------------------------------------------------------------------
Brick mdskvm-p01.nix.mds.xyz:/mnt/p01-d01/g
lusterv01 49152 0 Y
4375
Brick mdskvm-p02.nix.mds.xyz:/mnt/p02-d01/g
lusterv02 49152 0 Y
4376
NFS Server on localhost N/A N/A N N/A
Self-heal Daemon on localhost N/A N/A Y
4402
NFS Server on mdskvm-p01.nix.mds.xyz N/A N/A N N/A
Self-heal Daemon on mdskvm-p01.nix.mds.xyz N/A N/A Y
4384
Task Status of Volume mdsgv01
------------------------------------------------------------------------------
There are no active volume tasks
[root at mdskvm-p02 network-scripts]#
Would be handy to have a rename function in future releases.
Cheers,
TK
On 9/25/2019 7:47 AM, TomK wrote:
> Thanks Thorgeir. Since then I upgraded to Gluster 6. Though this issue
> remaind the same, anything in the way of new options to change what's
> displayed?
>
> Reason for the ask is that this get's inherited by oVirt when doing
> discovery of existing gluster volumes. So now I have an IP for a host,
> a short name for a host and FQDN's for the rest.
>
>
> [root at mdskvm-p02 glusterfs]# gluster volume status
> Status of volume: mdsgv01
> Gluster process TCP Port RDMA Port Online
> Pid
> ------------------------------------------------------------------------------
>
> Brick mdskvm-p02.nix.mds.xyz:/mnt/p02-d01/g
> lusterv02 49152 0 Y 22368
> Brick mdskvm-p01.nix.mds.xyz:/mnt/p01-d01/g
> lusterv01 49152 0 Y 24487
> NFS Server on localhost N/A N/A N
> N/A
> Self-heal Daemon on localhost N/A N/A Y 22406
> NFS Server on 192.168.0.60 N/A N/A N
> N/A
> Self-heal Daemon on 192.168.0.60 N/A N/A Y 25867
>
> Task Status of Volume mdsgv01
> ------------------------------------------------------------------------------
>
> There are no active volume tasks
>
> [root at mdskvm-p02 glusterfs]#
>
> Cheers,
> TK
>
> On 9/24/2019 2:58 AM, Thorgeir Marthinussen wrote:
>> In an effort to answer the actual question, in my experience the
>> Gluster internals captures the address the first time you probe
>> another node.
>> So if you're logged into the first node and probe the second using an
>> IP-address, that is what will "forever" be displayed by gluster
>> status, and if you use a hostname that's what will be shown.
>> Brick paths are captured when the brick is registered, so using a path
>> with IP will always show the IP as part of the path, and hostname will
>> show that, etc.
>>
>> I haven't verified, but the second node I believe will attempt a
>> reverse lookup of the first node (when probing first->second) and
>> record that name (if any) as the "primary" name of the first node.
>> Also good to know, nodes can have multiple names, the primary name is
>> the one "configured" during setup, and secondary names can be added by
>> probing them afterwards.
>> All IP/hostname/FQDN parts of the brick-path has to be known to the
>> cluster, by probing that IP/hostname/FQDN.
>>
>>
>> Best regards
>> *THORGEIR MARTHINUSSEN*
>>
>> -----Original Message-----
>> *From*: TomK <tomkcpr at mdevsys.com
>> <mailto:TomK%20%3ctomkcpr at mdevsys.com%3e>>
>> *Reply-To*: tomkcpr at mdevsys.com <mailto:tomkcpr at mdevsys.com>
>> *To*: gluster-users at gluster.org <mailto:gluster-users at gluster.org>
>> *Subject*: Re: [Gluster-users] Where does Gluster capture the
>> hostnames from?
>> *Date*: Mon, 23 Sep 2019 21:31:19 -0400
>>
>> 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 guess everyone sort of has his perspective on this topic.
>>>>
>>>> I don't want to take this thread on an off-topic conversation
>>>> (discussing the merits of having a local hosts file) but I do dissent,
>>>> and therefore had to respond, on the shortcut that using a local
>>>> etc/host file creates a fixed network configuration that can never
>>>> adapt as business needs change. I'm running a k8s infrastructure and
>>>> actually have local conf files, FWIW.
>>>>
>>>> Regards,
>>>>
>>>> Cédric
>>>>
>>>>
>>>> -----Original Message-----
>>>> From:
>>>> gluster-users-bounces at gluster.org
>>>> <mailto:gluster-users-bounces at gluster.org>
>>>> <
>>>> gluster-users-bounces at gluster.org
>>>> <mailto:gluster-users-bounces at gluster.org>
>>>> > On Behalf Of Joe Julian
>>>> Sent: lundi 23 septembre 2019 17:06
>>>> To:
>>>> gluster-users at gluster.org
>>>> <mailto:gluster-users at gluster.org>
>>>>
>>>> Subject: Re: [Gluster-users] Where does Gluster capture the hostnames
>>>> from?
>>>>
>>>> I disagree about it being "best practice" to lock yourself in to a
>>>> fixed network configuration that can never adapt as business needs
>>>> change.
>>>> There are other resilient ways of ensuring your hostnames resolve
>>>> consistently (so that your cluster doesn't run loose ;-)).
>>>>
>>>> On 9/23/19 7:38 AM, Strahil wrote:
>>>>> Also,
>>>>>
>>>>> It's more safe to have static entries for your cluster - after all if
>>>>> DNS fails for some reason - you don't want to loose your cluster.A
>>>>> kind of 'Best Practice'.
>>>>>
>>>>> Best Regards,
>>>>> Strahil NikolovOn Sep 23, 2019 15:01, TomK <
>>>>> tomkcpr at mdevsys.com
>>>>> <mailto:tomkcpr at mdevsys.com>
>>>>> > wrote:
>>>>>> Do I *really* need specific /etc/hosts entries when I have IPA?
>>>>>>
>>>>>> [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 ~]#
>>>>>>
>>>>>> I really shouldn't need too. ( Ref below, everything resolves fine.
>>>>>> )
>>>>>>
>>>>>> Cheers,
>>>>>> TK
>>>>>>
>>>>>>
>>>>>> On 9/23/2019 1:32 AM, Strahil wrote:
>>>>>>> Check your /etc/hosts for an entry like:
>>>>>>> 192.168.0.60 mdskvm-p01.nix.mds.xyz mdskvm-p01
>>>>>>>
>>>>>>> Best Regards,
>>>>>>> Strahil NikolovOn Sep 23, 2019 06:58, TomK <
>>>>>>> tomkcpr at mdevsys.com
>>>>>>> <mailto:tomkcpr at mdevsys.com>
>>>>>>> > wrote:
>>>>>>>> Hey All,
>>>>>>>>
>>>>>>>> Take the two hosts below as example. One host shows NFS Server on
>>>>>>>> 192.168.0.60 (FQDN is mdskvm-p01.nix.mds.xyz).
>>>>>>>>
>>>>>>>> The other shows mdskvm-p02 (FQDN is mdskvm-p02.nix.mds.xyz).
>>>>>>>>
>>>>>>>> Why is there no consistency or correct hostname resolution? Where
>>>>>>>> does gluster get the hostnames from?
>>>>>>>>
>>>>>>>>
>>>>>>>> [root at mdskvm-p02 glusterfs]# gluster volume status Status of
>>>>>>>> volume: mdsgv01 Gluster process TCP
>>>>>>>> Port RDMA Port Online Pid
>>>>>>>> -------------------------------------------------------------------
>>>>>>>> ----------- Brick mdskvm-p02.nix.mds.xyz:/mnt/p02-d01/g
>>>>>>>> lusterv02 49153 0 Y
>>>>>>>> 17503
>>>>>>>> Brick mdskvm-p01.nix.mds.xyz:/mnt/p01-d01/g
>>>>>>>> lusterv01 49153 0 Y
>>>>>>>> 15044
>>>>>>>> NFS Server on localhost N/A N/A N
>>>>>>>> N/A Self-heal Daemon on localhost N/A N/A
>>>>>>>> Y
>>>>>>>> 17531
>>>>>>>> NFS Server on 192.168.0.60 N/A N/A N
>>>>>>>> N/A Self-heal Daemon on 192.168.0.60 N/A N/A
>>>>>>>> Y
>>>>>>>> 15073
>>>>>>>>
>>>>>>>> Task Status of Volume mdsgv01
>>>>>>>> -------------------------------------------------------------------
>>>>>>>> -----------
>>>>>>>> There are no active volume tasks
>>>>>>>>
>>>>>>>> [root at mdskvm-p02 glusterfs]#
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> [root at mdskvm-p01 ~]# gluster volume status Status of volume:
>>>>>>>> mdsgv01 Gluster process TCP Port RDMA
>>>>>>>> Port Online Pid
>>>>>>>> -------------------------------------------------------------------
>>>>>>>> ----------- Brick mdskvm-p02.nix.mds.xyz:/mnt/p02-d01/g
>>>>>>>> lusterv02 49153 0 Y
>>>>>>>> 17503
>>>>>>>> Brick mdskvm-p01.nix.mds.xyz:/mnt/p01-d01/g
>>>>>>>> lusterv01 49153 0 Y
>>>>>>>> 15044
>>>>>>>> NFS Server on localhost N/A N/A N
>>>>>>>> N/A Self-heal Daemon on localhost N/A N/A
>>>>>>>> Y
>>>>>>>> 15073
>>>>>>>> NFS Server on mdskvm-p02 N/A N/A N
>>>>>>>> N/A Self-heal Daemon on mdskvm-p02 N/A N/A
>>>>>>>> Y
>>>>>>>> 17531
>>>>>>>>
>>>>>>>> Task Status of Volume mdsgv01
>>>>>>>> -------------------------------------------------------------------
>>>>>>>> -----------
>>>>>>>> There are no active volume tasks
>>>>>>>>
>>>>>>>> [root at mdskvm-p01 ~]#
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> But when verifying everything all seems fine:
>>>>>>>>
>>>>>>>>
>>>>>>>> (1):
>>>>>>>> [root at mdskvm-p01 glusterfs]# dig -x 192.168.0.39 ;; QUESTION
>>>>>>>> SECTION:
>>>>>>>> ;39.0.168.192.in-addr.arpa. IN PTR
>>>>>>>>
>>>>>>>> ;; ANSWER SECTION:
>>>>>>>> 39.0.168.192.in-addr.arpa. 1200 IN PTR
>>>>>>>> mdskvm-p02.nix.mds.xyz.
>>>>>>>> [root at mdskvm-p01 glusterfs]# hostname -f mdskvm-p01.nix.mds.xyz
>>>>>>>> [root at mdskvm-p01 glusterfs]# hostname -s
>>>>>>>> mdskvm-p01
>>>>>>>> [root at mdskvm-p01 glusterfs]# hostname mdskvm-p01.nix.mds.xyz
>>>>>>>> [root at mdskvm-p01 glusterfs]#
>>>>>>>>
>>>>>>>>
>>>>>>>> (2):
>>>>>>>>
>>>>>>>> [root at mdskvm-p02 glusterfs]# dig -x 192.168.0.60 ;; QUESTION
>>>>>>>> SECTION:
>>>>>>>> ;60.0.168.192.in-addr.arpa. IN PTR
>>>>>>>>
>>>>>>>> ;; ANSWER SECTION:
>>>>>>>> 60.0.168.192.in-addr.arpa. 1200 IN PTR
>>>>>>>> mdskvm-p01.nix.mds.xyz.
>>>>>>>>
>>>>>>>> [root at mdskvm-p02 glusterfs]# hostname -s
>>>>>>>> mdskvm-p02
>>>>>>>> [root at mdskvm-p02 glusterfs]# hostname -f mdskvm-p02.nix.mds.xyz
>>>>>>>> [root at mdskvm-p02 glusterfs]# hostname mdskvm-p02.nix.mds.xyz
>>>>>>>> [root at mdskvm-p02 glusterfs]#
>>>>>>>>
>>>>>>>>
>>>>>>>> Gluster version used is:
>>>>>>>>
>>>>>>>> [root at mdskvm-p01 glusterfs]# rpm -aq|grep -Ei gluster
>>>>>>>> glusterfs-server-3.12.15-1.el7.x86_64
>>>>>>>> glusterfs-client-xlators-3.12.15-1.el7.x86_64
>>>>>>>> glusterfs-rdma-3.12.15-1.el7.x86_64
>>>>>>>> glusterfs-3.12.15-1.el7.x86_64
>>>>>>>> glusterfs-events-3.12.15-1.el7.x86_64
>>>>>>>> libvirt-daemon-driver-storage-gluster-4.5.0-10.el7_6.12.x86_64
>>>>>>>> glusterfs-libs-3.12.15-1.el7.x86_64
>>>>>>>> glusterfs-fuse-3.12.15-1.el7.x86_64
>>>>>>>> glusterfs-geo-replication-3.12.15-1.el7.x86_64
>>>>>>>> python2-gluster-3.12.15-1.el7.x86_64
>>>>> ________
>>>>>
>>>>> Community Meeting Calendar:
>>>>>
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>>>>>
>>>>>
>>>>> NA/EMEA Schedule -
>>>>> Every 1st and 3rd Tuesday at 01:00 PM EDT
>>>>> Bridge:
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>>>>>
>>>>>
>>>>> Gluster-users mailing list
>>>>> Gluster-users at gluster.org
>>>>> <mailto:Gluster-users at gluster.org>
>>>>>
>>>>> https://lists.gluster.org/mailman/listinfo/gluster-users
>>>>>
>>>> ________
>>>>
>>>> Community Meeting Calendar:
>>>>
>>>> APAC Schedule -
>>>> Every 2nd and 4th Tuesday at 11:30 AM IST
>>>> Bridge:
>>>> https://bluejeans.com/118564314
>>>>
>>>>
>>>> NA/EMEA Schedule -
>>>> Every 1st and 3rd Tuesday at 01:00 PM EDT
>>>> Bridge:
>>>> https://bluejeans.com/118564314
>>>>
>>>>
>>>> Gluster-users mailing list
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>>>>
>>>> https://lists.gluster.org/mailman/listinfo/gluster-users
>>>>
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>>>>
>>>> Community Meeting Calendar:
>>>>
>>>> APAC Schedule -
>>>> Every 2nd and 4th Tuesday at 11:30 AM IST
>>>> Bridge:
>>>> https://bluejeans.com/118564314
>>>>
>>>>
>>>> NA/EMEA Schedule -
>>>> Every 1st and 3rd Tuesday at 01:00 PM EDT
>>>> Bridge:
>>>> https://bluejeans.com/118564314
>>>>
>>>>
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>>>> <mailto:Gluster-users at gluster.org>
>>>>
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>>>>
>>> ________
>>>
>>> Community Meeting Calendar:
>>>
>>> APAC Schedule -
>>> Every 2nd and 4th Tuesday at 11:30 AM IST
>>> Bridge:
>>> https://bluejeans.com/118564314
>>>
>>>
>>> NA/EMEA Schedule -
>>> Every 1st and 3rd Tuesday at 01:00 PM EDT
>>> Bridge:
>>> https://bluejeans.com/118564314
>>>
>>>
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>>>
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>>>
>>
>>
>>
>> ________
>>
>> Community Meeting Calendar:
>>
>> APAC Schedule -
>> Every 2nd and 4th Tuesday at 11:30 AM IST
>> Bridge: https://bluejeans.com/118564314
>>
>> NA/EMEA Schedule -
>> Every 1st and 3rd Tuesday at 01:00 PM EDT
>> Bridge: https://bluejeans.com/118564314
>>
>> Gluster-users mailing list
>> Gluster-users at gluster.org
>> https://lists.gluster.org/mailman/listinfo/gluster-users
>>
>
>
--
Thx,
TK.
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