DNS and DHCP will still work from the Service Node, if setup correctly. In other words, you have configured the service node as the DNS server and/or DHCP server for the nodes and there is no requirement on the Management Node for dns or dhcp. You will not be able to run any xcat commands on the service node, if the Management Node is down. xCAT requires access to the database configured on the MN for the xcat cluster ( mysql, postgresql) to run most xcat commands. Even to recognize that the node is in the xcat cluster.
Lissa K. Valletta
8-3/B10
Poughkeepsie, NY 12601
(tie 293) 433-3102
From: Josh Nielsen <jniel...@hudsonalpha.org>
To: xCAT Users Mailing list <xcat-user@lists.sourceforge.net>,
Date: 01/10/2014 12:59 PM
Subject: Re: [xcat-user] How to create and deploy an xCAT Service Node
Hi Wang Xiaopeng (I apologize if I got your name wrong before),
You said: "SN cannot work without MN since there's only one database which
is running on MN. If MN is down you cannot run lots of commands on SN. In
fact xCAT does NOT recommend to run any command on SN."
Will DNS and DHCP still work however from an SN when the MN is down? I
would need the SN to still resolve the compute nodes' DNS requests on the
cluster subnet and issue DHCP leases/renewals as necessary. It looks like
SNs are intended to take responsibility on behalf of the MN for serving the
compute nodes' necessary services, such that you designate each node's
"xcatmaster" as the SN like: chdef -t group compute1 servicenode=sn1
xcatmaster=sn1-nic. If that is the case then shouldn't DNS & DHCP still be
resolved from the SN by a node even when the MN is down?
Thanks,
Josh
On Wed, Jan 8, 2014 at 6:32 PM, Xiao Peng Wang <w...@cn.ibm.com> wrote:
The doc mentioned by Josh will lead you in the correct direction to setup
Service Node.
Several information for you:
Roughly, your understand is correct that you can install and
configure a SN automatically when prepare/configure correctly for
SNnode definition (correct group like service, correct attribute
like postscripts, correct osimage like
rhels6.4-x86_64-install-service) and xCAT rpm repository.
Generally, the /tftpboot and /install on SN are mounted from xCAT
MN, so them will be identical with the dirs on MN in any time.
SN cannot work without MN since there's only one database which is
running on MN. If MN is down you cannot run lots of commands on SN.
In fact xCAT does NOT recommend to run any command on SN.
Thanks
Best Regards
----------------------------------------------------------------------
Wang Xiaopeng (王晓朋)
IBM China System Technology Laboratory
Tel: 86-10-82453455
Email: w...@cn.ibm.com
Address: 28,ZhongGuanCun Software Park,No.8 Dong Bei Wang West Road,
Haidian District Beijing P.R.China 100193
Inactive hide details for Josh Nielsen ---2014/01/09 03:48:01---Hi
Russell, For some reason that wiki page never came up in my Josh Nielsen
---2014/01/09 03:48:01---Hi Russell, For some reason that wiki page never
came up in my Google searches even
From: Josh Nielsen <jniel...@hudsonalpha.org>
To: xCAT Users Mailing list <xcat-user@lists.sourceforge.net>,
Date: 2014/01/09 03:48
Subject: Re: [xcat-user] How to create and deploy an xCAT Service Node
Hi Russell,
For some reason that wiki page never came up in my Google searches even
when I placed quotes around "service node". Thanks! I'll take a look
through it.
Regards,
Josh
On Wed, Jan 8, 2014 at 12:25 PM, Russell Jones <russell-l...@jonesmail.me
> wrote:
Hi Josh,
This should be helpful for you (it was for me when first learning
how to set this up):
http://sourceforge.net/apps/mediawiki/xcat/index.php?title=Setting_Up_a_Linux_Hierarchical_Cluster
On 1/8/2014 11:52 AM, Josh Nielsen wrote:
Hello all,
I am trying to move my xCAT installation toward a
hierarchical structure by including Service Nodes but I am
finding a dearth of information on how to create a service
node on the xCAT wiki and even the Sumavi xCAT guide. At
first I began following the instructions for a setting up a
management node (which involves a new xCAT install, an
independent xCAT database, etc.) on a VM intended to the the
SN but then realized that that must be wrong.
I have noticed the xCAT 'servicenode' database table present
on the Management Node (listed with tabdump). I am wondering
if I can simply designate a new node (in my case a VM) to be
the prospective SN, designate which services (like dhcp, dns,
etc.) to enable/disable in the 'servicenode' table, and then
do a fresh 'rinstall' to that VM and have it be automatically
& fully configured as an SN from postinstall scripts (which I
presume are already present and will be automatically applied
to that node by some xCAT logic of parsing the 'servicenode'
table and associating any relevant postscripts to be run with
the node).
If so will it create the /install and /tftpboot directories
(including ISOs made with copycds) on each SN identical to
the contents of the MN? Is it that simple or is there more
involved than that?
In addition I want to be able to take down the Management
Node in the future for maintenance and be able to do just
about everything that the MN can do from the SNs (including
dhcp leases, rpower commands, updatenode, psh, etc) while the
MN is down. Is that possible? Any clarifications would be
appreciated.
Thank you,
Josh Nielsen
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