Re: Dependencies in resources

Scooter Morris <scooter@xxxxxxxxxxxx> · Fri, 24 Jul 2009 09:59:46 -0700

Alfredo,

    Thanks!  That was very helpful, although I have a couple more
questions for the list.  What I am trying to do seems well suited for
the existing "depend" and "depend-mode" capability.  Essentially, I'm
trying to use this to "group" services.  So, assume I have 3 services:
A, B, and C (in my case, A is an IP service, B and C both have an fs
and a script resource).  I want B and C to depend on A such that B and
C will only start on the node where A is running.  I assume I can do
this by:

   <service autostart="1" name="B" recovery="relocate"
depend="service:A" depend-mode="hard">

      <fs ... />

      <script .../>

    </service>

    <service autostart="1" name="C" depend="service:A"
depend-mode="hard">

      <fs .../>

      <script .../>

    </service>

    <service autostart="1" name="A" recovery="relocate">

      <ip ref="xxx.xxx.xxx.xxx"/>

    </service>

Unfortunately, this didn't work as expected.  If I start A on node 1,
services B and C seem perfectly happy to run on any other node.  If a
coerce everybody on the same node, and relocate (or disable A),
services B and C continue on blissfully ignoring the status of A.  Do I
need to write and event handler for this situation (which seems much
simpler than the follow-service script)?

Again, thanks in advance!

-- scooter

Moralejo, Alfredo wrote:

  Take a look
into

  https://inquiries.redhat.com/go/redhat/ReferenceArchitectureSAPClusterSuite

  Deploying
Highly Available SAP Servers
using Red Hat Cluster Suite

  Gives some
example about dependencies on
services etc..

  A very good
document

  From: linux-cluster-bounces@xxxxxxxxxx
[mailto:linux-cluster-bounces@xxxxxxxxxx] On
Behalf Of Scooter Morris

  Sent: Thursday, July
23, 2009
11:08 PM

  To: linux clustering

  Subject:

Dependencies in resources

  Hi all,

    I saw in a message on the net about a depends="service:xxxx" option
for
services in cluster.conf for 5.3beta.  Did this single-level dependency
support make it into the 5.3 release?  It would be really, really
useful
if it did!  If not, can anyone suggest a way that I can have a multiple
services depend on a single IP?

Thanks in advance!

-- scooter

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