[Linux-cluster] Resource tree in service?

[emmanuel segura]

Hello Jakov

rgmanager has an internal order and this order is used to know what the
services (start|stod) sequence

vim +/special/ /usr/share/cluster/service.sh

So sometime force i the hierarchy in the service definetion is not needed

2013/2/18 Jakov Sosic <jsosic at srce.hr>

> Hi.
>
> First of all, I'm running CentOS 6.3. Now, my problem is the following.
> I have this kind of resource tree in my service:
>
> <service autostart="0" domain="domain12" name="pgmaster">
>    <ip ref="192.168.50.101">
>       <ip ref="10.200.200.101">
>          <fs ref="intern">
>             <postgres-8 ref="pgmaster"/>
>          </fs>
>       </ip>
>    </ip>
> </service>
>
>
> This configuration in cluster.conf starts postgresql in a way that
> database listens only on the first ip address of the service
> (listen='192.168.50.101').
>
> If I reorder the code to look like this:
>
>
> <service autostart="0" domain="domain12" name="pgmaster">
>    <fs ref="intern">
>       <ip ref="192.168.50.101">
>          <ip ref="10.200.200.101">
>             <postgres-8 ref="pgmaster"/>
>          </ip>
>       </ip>
>    </fs>
> </service>
>
> then postgres can't even start because no IP address was found (listen='').
>
> So, script obviously checks only first level of hierarchy in the
> cluster.conf.
>
> I've examined the script further, and found out that postgres-8.sh uses
> bash function 'build_ip_list()' from "config-utils.sh" script.
>
> That function iterates through ip's, by using ccs_tool, like this:
>
> # ccs_tool query '/cluster/rm/service[@name="pgmaster"]/ip[$x]/@ref'
>
> $x is integer that equals 1, and is being iterated until ccs_tool
> returns error.
>
> In the first case presented, this is the output that I get:
>
> # ccs_tool query '/cluster/rm/service[@name="pgmaster"]/ip[1]/@ref'
> 192.168.50.101
>
> # echo $?
> 0
>
> # ccs_tool query '/cluster/rm/service[@name="pgmaster"]/ip[2]/@ref'
> Query failed: Invalid argument
>
> # echo $?
> 1
>
>
> Now, for the current state of scripts to work ok, I have to model my
> service in this manner:
>
> <service autostart="0" domain="domain12" name="pgmaster">
>    <ip ref="192.168.50.101"/>
>    <ip ref="10.200.200.101"/>
>    <fs ref="intern">
>       <postgres-8 ref="pgmaster"/>
>    </fs>
> </service>
>
> Now both IP addresses get figured out by ccs_tool query, and postgresql
> starts fine with listen='192.168.50.101,10.200.200.101'.
>
>
> My question is, is this a bug, or should I always put all my ip
> addresses at the root level of service hierarchy, out of dependency tree?
>
> And is this a problem for a service, I mean, what is the ordering in
> which resources are started? In this scenario if the order of execution
> of resources isn't deterministic but random, there is a possibility for
> a service to fail, if IP addresses didn't get up before the service
> started.
>
> If that's not the case, and if ip addresses have to be in the dependency
> relation to other resources, then "config-utils.sh" script should have
> to be rewritten, in a way that searches for IP addresses deeply in a
> hierarchy and not only at root level...
>
>
>
>
> Thank you for all your comments.
>
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>



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