Service Guard Order/Priority Packages Halt.

[Maigualida]

Hello guys,

Somebody knows where obtains the daemon of packages of service guard the order of packages when executing cmhaltcl?

Thank you

PS = Is my first time in the forum, and wanted to congratulate them by the technical support that offers us day to day.

[Francesco Campalastri]

Hi Maigualida, welcome to you.

there are no rules halting packages. They halt alltogether.

Remember that giving the command from one node, the remote node will have remsh command execution. The remote packages will halt a little bit slower.


If you need to order the application halt you need to organize the "waits" into the control scripts.


Bye

[Maigualida]

Thanx Francesco for the quick answer,

My question this directed but well, to the scene of K packages in a node, and I require that one of them stops first who another one, for examplem case of NFS with some database.

I have observed, maybe by chance, that the halting is made by alfabetical order in the same node...

if nfs_pkg and oracle_pkg exist en /etc/cmcluster, stops first a NFS and soon oracle, you see?

I am going to review waits and I comment to you.

Thanks again...

[A. Clay Stephenson · Accepted solution]

There really is no defined order of package startup and shutdown. Bear in mind that the packages may well be on different nodes.

Cmhaltcl commands are very rare. I can't think of a time (other than development) when I've done it without halting the packages.

If package A depends upon Package B then I would tend to combine them in a single package or write some rather tricky startup/halt package scripts. If the packages are on the same node then you can simply test for the existence of a file but if on different nodes then it becomes more involved.

One technique that you might find useful is a set of multi-host semaphores built around Perl sockets.

See this thread:
http://forums.itrc.hp.com/cm/QuestionAnswer/1,,0x312e8f960573d611abdb0090277a778c,00.html

or for a better explanation see the April 2003 issue of SysAdmin magazine (www.sysadmin.com) where I explained this in better detail. The above example and the magazine article dealt with backup issues but the exact issues can also arise with MC/SG.

Regards, Clay

[Sridhar Bhaskarla]

Hi,

'cmhaltcl' should ask you to bring down the packages before you could shutdown the cluster unless you use it with "-f" option which is very uncommon. With "-f" all are simultaneously brought down.

If you are maintaining the cluster someone else configured, you may want to look into the scripts to see how they were written. It is a common practice to put dependencies in the package script startup/shutdown scripts that would affect the order.

-Sri

[John Poff]

Hi,

As mentioned above, if you need the packages to stop and start in a certain order you should control them in a package script.

I think that if you just issue a cmhaltcl/cmruncl command, the packages will be halted/started in the order that they were added to the cluster via cmapplyconf.

JP

[Maigualida]

Thanks Clay, Jhon and to all by its answers,

The question arose in the course h6487, where we proved combinations of flags in cntl scripts of three packages, that as Clay comments, works if the packages are in the same node, that was the case of study...

But I thought that some other method existed with which package manager initiated/stopped the packages, and if it existed, so that to work of more? ;)

Jhon comments about the order of application of cmapplyconf, and thinking it, it is the form in which the daemon finds out as packages must administer. has sense

it sounds interesting to create pl for packages in different nodes, I must prove it .

It seems to me interesting to know about the SG demons (cmcld, cmlogd, cmlvmd, etc), to finalize this subject, some of you it knows where could find detail of operation of the daemons? in addition to the material of HA in doc.hp.com?

Thanx :)
Regards.

[melvyn burnard]

If any one is interested, the SG diivision have put together a small set of tools, knowon as the
HA Reference Architecture Toolkit, or HARAT.
This will be presented to htis Autumn's HPWORLD attendees, but here is hte basic information.
The HARA Toolkit is a simplified and improved version of a previously designed set of tools. The haratoolkit.tar file will untar to /opt/cmcluster/harat and the HARA Toolkit Users Guide is what documentation is available. These scripts are distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
One of hte parts of this toolkit is the ability to create packahes wiht dependencies upon other paqckages being up or down.
I attach the pdf file, which hopefullly you will be able to read.