Resources allocation when the machine reboots

[Enrico Venturi]

Hello colleagues
I've a system composed by 3 machines: A, B and C.
A allocates some resources, e.g. shared disks and virtual IP's, then it is stopped for (supposing) maintenance reasons.
In the meanwhile B is running, it detects the A stop and it decides to allocates those resources for itself, i.e. it allocates the shared disks and the virtual IP ...
As soon as the machine A restarts it could try to allocate again the resources, therefore a conflict can arise....
No, my question is:
when the machine restarts, does it try automatically to allocate any previously used resources? or not?
Is there eny mechanism to avoid that?
I guess it's possible to allocate the resources in a "volatile" way ... or something similar.
Any helps?

thanks a lot
Enrico

[Luk Vandenbussche · Accepted solution]

Volumegroups are activated at startup when the value of AUTO_VG_ACTIVE=1
You find this value in the file /etc/lvmrc.

I hope you mean with resource allocation only the filesystems?

Be aware that there can also be problems with the virtual IP adress, when they are automaticly active at startup

[Sridhar Bhaskarla]

Hi Enrico,

What you are talking is 'exactly' what serviceguard does. I looked at your previous posts and saw one with "Getting rid of ServiceGuard" subject. So, looks like you really got rid of serviceguard?

It is possible to allocate the resources in a 'volatile'? May be. But it is easier and safer with ServiceGuard. Otherwise, you will have to write quite a bit of scripting to simulate Serviceguard behaviour and I can assure that still it can get you into trouble.

I can only give you ideas on which you have to develop the solution yourselves. Do not enable shared VGs on reboot through /etc/lvmrc. Do not add the floating IP in netconf file. Instead have a script that starts either through crontab or through startup but runs continuously with some sleep in between - that checks to see if the VGs are activated on the other node (either through SSH or REMSH) and the floating IP activated etc.,. If not, activate them. Have the same script running on the other box. Or to be much safer, get paged whenever the systems go down and do the stuff manually.

Well..if I were you, I wouldn't do anything above. I would convince my management to buy Serviceguard for me if they think that the servers are too critical.

-Sri