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Re: [Linux-cluster] Cluster Setup Questions

iana wrote:

---------------8< snip, snip ---------------------------------

What has to be decided:
Currently, no fencing is decided and two options are considered:
1. APC AP7921 Rack PDUs (still don't quite imagine how it'll work
with servers with dual power supplies, but this can be solved)
2. Integrated IBM Slimline RSA II controller (Don't know if it's
supported by RHCS).

We have a fence agent for RSA II, but it has never been tested with the slimline controller; only the standard RSA II controller.

AP7921 is a supported power switch and a good choice. In a dual power supply environment, just configure the general device in the UI under fence devices, then configure two fences for each node (on the same fence level). The ui app will note that there are two power fences on the level and then write the correct 'off-on' sequence into the conf file. If you have any questions about the conf file and dual power supplies, just post your file here and someone will be able to help.


I  found  from  the  mailing  list, that there are problems with power
fencing   when  losing  LAN  connectivity  (no  heartbeat  =>  servers
powercycle each other). Haven't found a way to overcome it, though ;(

The  manual says that RHCS can work with single storage only. Is there
a  way  to  overcome it without storage virtualization? I really don't
want building software RAID arrays over MAN.

If  not  - I can establish SAN mirroring then, and mirror all the suff
from  "primary"  storage  to  backup  storage.  Is there a way to make
cluster   automatically   check   health   of   "active"  storage  and
automatically  remount  FS  from backup storage if active storage goes
down?  The only solution I found is to do this from customized service
status script..

If  so  -  can I run the cluster without common FS resource? My simple
tests show that that's possible, but want proofs.

The questions:
Besides the questions asked above, the two main questions are:
* How should I design the cluster so it works like I want?
* How should I implement it?

Some smaller questions:
* If the status script returns 0 - status is ok. What happens if not?
Does the Cluster Software first try to restart the service or fails it
over to the next node? If tries to restart - by which means ('service
XXX restart', kill -9, or smth else)?

*  How  does  cluster  software  check  the  status  of infrastructure
resources  (IPs,  FSes, heartbeat). Can I change the course of actions
there by writing my own scripts?

Thanks in advance to those brave enough to answer =)

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