Re: [gpfsug-discuss] Dual server NSDs - change of hostname

[Uwe Falke]

Hi John, 

some last thoughts
mmdelnode/mmaddnode is an easy way to move non-NSD servers, but doing so 
for NSD servers requires to run mmchnsd, and that again requires a 
downtime for the file system the NSDs are part of (in Scale 4 at least, 
what we are talking right here). That could only be circumvented by 
mmdeldisk/mmadddisk the NSDs of the NSD server to be moved (with all the 
restriping).
If that's ok for you go ahead. 

Else I think you might give the mmchnode way a second thought. I'd stop 
GPFS on the server to be moved (although  that should also be 
hot-swappable) which should prevent any havoc for Scale and offers you 
plenty of opportunity to check your final new network set-up, before 
starting Scale on that renewed node. 

YMMV, and you might try different methods on your test system of course. 

 
Mit freundlichen Grüßen / Kind regards

 
Dr. Uwe Falke
 
IT Specialist
High Performance Computing Services / Integrated Technology Services / 
Data Center Services
---
IBM Deutschland
Rathausstr. 7
09111 Chemnitz
Phone: +49 371 6978 2165
Mobile: +49 175 575 2877
E-Mail: uwefa...@de.ibm.com
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IBM Deutschland Business & Technology Services GmbH / Geschäftsführung: 
Thomas Wolter, Sven Schooß
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HRB 17122 


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Re: [gpfsug-discuss] Dual server NSDs - change of hostname

[John Hearns]

Thankyou everyone for replies on this issue. Very helpful.

We have a test setup with three nodes, although no multi-pathed disks. So I can 
try out removing and replacing disks servers.
I agree with Simon that bringing up a second NIC is probably inviting Murphy in 
to play merry hell…

The option we are envisioning is re-installing the server(s) but leaving them 
with the existing FQDNs if we can.



From: gpfsug-discuss-boun...@spectrumscale.org 
[mailto:gpfsug-discuss-boun...@spectrumscale.org] On Behalf Of Simon Thompson 
(IT Research Support)
Sent: Thursday, April 05, 2018 4:28 PM
To: gpfsug main discussion list 
Subject: Re: [gpfsug-discuss] Dual server NSDs - change of hostname

Yeah that was my thoughts too given Bob said you can update the server list for 
an NSD device in 5.0. I also thought that bringing up a second nic and changing 
the name etc could bring a whole world or danger from having split routing and 
rp_filter (been there, had the weirdness, RDMA traffic continues but admin 
traffic randomly fails, but hey, if you like the world crashing down around 
you….)

Simon

From: 
mailto:gpfsug-discuss-boun...@spectrumscale.org>>
 on behalf of "makap...@us.ibm.com<mailto:makap...@us.ibm.com>" 
mailto:makap...@us.ibm.com>>
Reply-To: 
"gpfsug-discuss@spectrumscale.org<mailto:gpfsug-discuss@spectrumscale.org>" 
mailto:gpfsug-discuss@spectrumscale.org>>
Date: Thursday, 5 April 2018 at 14:37
To: "gpfsug-discuss@spectrumscale.org<mailto:gpfsug-discuss@spectrumscale.org>" 
mailto:gpfsug-discuss@spectrumscale.org>>
Subject: Re: [gpfsug-discuss] Dual server NSDs - change of hostname

To my mind this is simpler:  IF you can mmdelnode without too much suffering, 
do that. Then reconfigure the host name and whatever else you'd like to do. 
Then mmaddnode...

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Re: [gpfsug-discuss] Dual server NSDs - change of hostname

[Simon Thompson (IT Research Support)]

Yeah that was my thoughts too given Bob said you can update the server list for 
an NSD device in 5.0. I also thought that bringing up a second nic and changing 
the name etc could bring a whole world or danger from having split routing and 
rp_filter (been there, had the weirdness, RDMA traffic continues but admin 
traffic randomly fails, but hey, if you like the world crashing down around 
you….)

Simon

From:  on behalf of 
"makap...@us.ibm.com" 
Reply-To: "gpfsug-discuss@spectrumscale.org" 
Date: Thursday, 5 April 2018 at 14:37
To: "gpfsug-discuss@spectrumscale.org" 
Subject: Re: [gpfsug-discuss] Dual server NSDs - change of hostname

To my mind this is simpler:  IF you can mmdelnode without too much suffering, 
do that. Then reconfigure the host name and whatever else you'd like to do. 
Then mmaddnode...


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Re: [gpfsug-discuss] Dual server NSDs - change of hostname

[Marc A Kaplan]

To my mind this is simpler:  IF you can mmdelnode without too much 
suffering, do that. Then reconfigure the host name and whatever else you'd 
like to do. Then mmaddnode...


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Re: [gpfsug-discuss] Dual server NSDs - change of hostname

[Uwe Falke]

Hm, 
you can change the host name of a Scale node.
I've done that a while ago on one or two clusters. 

>From what I remember I'd follow these steps: 

1. Upgrade the OS configuring/using the old IP addr/hostname
(2. Reinstall Scale)
(3. Replay the cluster data on the node)
4. Create an interface with the new IP address on the node (not 
necessarily connected)
5. Ensure the node is not required for quorum and has currently no mgr 
role. You might want to stop Scale on the node.
5. mmchnode -N  --daemon-interface  ; mmchnode -N 
 --admin-interface . Now the node has kind of 
disappeared, if the new IF is not yet functional, until you bring that IF 
up (6.)
(6. Activate connection to other cluster nodes via new IF)

2. and 3. are required if scale was removed / the system was re-set up 
from scratch
6. is required if the new IP connection config.ed in 4 is not operational 
at first (e.g. not yet linked, or routing not yet active, ...) 


Et voila, the server should be happy again, if stopped before, start up 
Scale and check.

No warranties, 
But that's how I'd try. 
As usual: if messing with IP config, be sure to have a back door to the 
system in case you ground the OS network config . 


 
Mit freundlichen Grüßen / Kind regards

 
Dr. Uwe Falke
 
IT Specialist
High Performance Computing Services / Integrated Technology Services / 
Data Center Services
---
IBM Deutschland
Rathausstr. 7
09111 Chemnitz
Phone: +49 371 6978 2165
Mobile: +49 175 575 2877
E-Mail: uwefa...@de.ibm.com
---
IBM Deutschland Business & Technology Services GmbH / Geschäftsführung: 
Thomas Wolter, Sven Schooß
Sitz der Gesellschaft: Ehningen / Registergericht: Amtsgericht Stuttgart, 
HRB 17122 




From:   John Hearns 
To: gpfsug main discussion list 
Date:   04/04/2018 21:33
Subject:[gpfsug-discuss] Dual server NSDs - change of hostname
Sent by:gpfsug-discuss-boun...@spectrumscale.org



Following up from my previous email (I should reply to that email I know)
What we really want to achieve is changing the FQDN of an existing server.
The server will be reinstalled with an updated OS (RHEL 6-à RHEL 7)
During the move we wish to change the domain name of the server.
So we will be taking the server offline and bringing the same physical 
server back up with a new domain name.
Has anyone done a procedure like this?
 
Thankyou
 
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Re: [gpfsug-discuss] Dual server NSDs

[Alex Levin]

We are doing the similar procedure right now. Migrating from one group of
nsd servers to another.
Unfortunately,  as I understand,  if you can't afford the
cluster/filesystem downtime and not ready for 5.0 upgrade yet ( personally
I'm not comfortable with ".0" versions of software in production :) ) - the
only way to do it is remove disk/nsd from filesystem and add it back with
the new servers list.

Taking a while , a lot of i/o ...

John, in case the  single nsd filesystem, I'm afraid,  you'll have to
unmount it to change 

--Alex



On Wed, Apr 4, 2018, 2:25 PM Buterbaugh, Kevin L <
kevin.buterba...@vanderbilt.edu> wrote:

> Hi John,
>
> Yes, you can remove one of the servers and yes, we’ve done it and yes, the
> documentation is clear and correct.  ;-)
>
> Last time I did this we were in a full cluster downtime, so unmounting
> wasn’t an issue.  We were changing our network architecture and so the IP
> addresses of all NSD servers save one were changing.  It was a bit …
> uncomfortable … for the brief period of time I had to make the one NSD
> server the one and only NSD server for ~1 PB of storage!  But it worked
> just fine…
>
> HTHAL…
>
> Kevin
>
> On Apr 4, 2018, at 4:11 AM, John Hearns  wrote:
>
> I should say I already have a support ticket open for advice on this issue.
> We have a filesystem which has NSDs which have two servers defined, for
> instance:
> nsd:
>   device=/dev/sdb
>   servers=sn007,sn008
>   nsd=nsd1
>   usage=dataOnly
>
> Can I remove one of these servers?  The object is to upgrade this server
> and change its hostname, the physical server will stay in place.
> Has anyone carried out an operation similar to this?
>
> I guess the documentation here is quite clear:
>
> https://www.ibm.com/developerworks/community/wikis/home?lang=en#!/wiki/General%20Parallel%20File%20System%20(GPFS)/page/NSD%20server%20balance
> 
> “If you want to change configuration for a NSD which is already belongs
> to a file system, you need to unmount the file system before running
> mmchnsd command.”
> -- The information contained in this communication and any attachments is
> confidential and may be privileged, and is for the sole use of the intended
> recipient(s). Any unauthorized review, use, disclosure or distribution is
> prohibited. Unless explicitly stated otherwise in the body of this
> communication or the attachment thereto (if any), the information is
> provided on an AS-IS basis without any express or implied warranties or
> liabilities. To the extent you are relying on this information, you are
> doing so at your own risk. If you are not the intended recipient, please
> notify the sender immediately by replying to this message and destroy all
> copies of this message and any attachments. Neither the sender nor the
> company/group of companies he or she represents shall be liable for the
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Re: [gpfsug-discuss] Dual server NSDs

[Buterbaugh, Kevin L]

Hi John,

Yes, you can remove one of the servers and yes, we’ve done it and yes, the 
documentation is clear and correct.  ;-)

Last time I did this we were in a full cluster downtime, so unmounting wasn’t 
an issue.  We were changing our network architecture and so the IP addresses of 
all NSD servers save one were changing.  It was a bit … uncomfortable … for the 
brief period of time I had to make the one NSD server the one and only NSD 
server for ~1 PB of storage!  But it worked just fine…

HTHAL…

Kevin

On Apr 4, 2018, at 4:11 AM, John Hearns 
mailto:john.hea...@asml.com>> wrote:

I should say I already have a support ticket open for advice on this issue.
We have a filesystem which has NSDs which have two servers defined, for 
instance:
nsd:
  device=/dev/sdb
  servers=sn007,sn008
  nsd=nsd1
  usage=dataOnly

Can I remove one of these servers?  The object is to upgrade this server and 
change its hostname, the physical server will stay in place.
Has anyone carried out an operation similar to this?

I guess the documentation here is quite clear:
https://www.ibm.com/developerworks/community/wikis/home?lang=en#!/wiki/General%20Parallel%20File%20System%20(GPFS)/page/NSD%20server%20balance
“If you want to change configuration for a NSD which is already belongs to a 
file system, you need to unmount the file system before running mmchnsd 
command.”
-- The information contained in this communication and any attachments is 
confidential and may be privileged, and is for the sole use of the intended 
recipient(s). Any unauthorized review, use, disclosure or distribution is 
prohibited. Unless explicitly stated otherwise in the body of this 
communication or the attachment thereto (if any), the information is provided 
on an AS-IS basis without any express or implied warranties or liabilities. To 
the extent you are relying on this information, you are doing so at your own 
risk. If you are not the intended recipient, please notify the sender 
immediately by replying to this message and destroy all copies of this message 
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Re: [gpfsug-discuss] Dual server NSDs - change of hostname

[valdis . kletnieks]

On Wed, 04 Apr 2018 10:02:09 -, John Hearns said:

> Has anyone done a procedure like this?

We recently got to rename all 10 nodes in a GPFS cluster to make the
unqualified name unique (turned out that having 2 nodes called 'arnsd1.isb.mgt'
and 'arnsd1.vtc.mgt' causes all sorts of confusion). So they got renamed to
arnsd1-isb.yadda.yadda and arnsd1-vtc.yadda.yadda.

Unmount, did the mmchnsd server list thing, start going through the servers,
rename and reboot each one.  We did hit a whoopsie because I forgot to fix the
list of quorum/manager nodes as we did each node - so don't forget to run
mmchnode for each system if/when appropriate...

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Re: [gpfsug-discuss] Dual server NSDs

[Oesterlin, Robert]

Short answer is that if you want to change/remove the NSD server config on an 
NSD and its part of a file systems, you need to remove it from the file system 
or unmount the file system. *Thankfully* this is changed in Scale 5.0.

In your case (host name change) – if the IP address of the NSD server stays the 
same you *may* be OK. Can you put a DNS alias in for the old host name? Well, 
now that I think about it the old host name will stick around in the config – 
so maybe not such a great idea.


Bob Oesterlin
Sr Principal Storage Engineer, Nuance

From:  on behalf of John Hearns 

Reply-To: gpfsug main discussion list 
Date: Wednesday, April 4, 2018 at 1:46 PM
To: gpfsug main discussion list 
Subject: [EXTERNAL] [gpfsug-discuss] Dual server NSDs

Can I remove one of these servers?  The object is to upgrade this server and 
change its hostname, the physical server will stay in place.
Has anyone carried out an operation similar to this?
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