Re: oracle rac 10g and OS clusterware.
- From: Dan Norris <dannorris@xxxxxxxxxxxxx>
- To: john.hallas@xxxxxxxxxx, ujang.jaenudin@xxxxxxxxx, Peter McLarty <peter.mclarty@xxxxxxxxxxxxxxxxxx>
- Date: Wed, 5 Dec 2007 18:36:17 -0800 (PST)
Thanks for the love, John :).
In my experience, node eviction only takes place when there's a component
failure in the cluster. From what I've seen, that's almost always a hardware
failure and I'd characterize it as "rare". However, as I'm sure someone will
point out if I don't say it, if it happens just one time ever, that's all it
takes to cause a very big problem if the cluster doesn't detect the failure
properly and handle it properly (and quickly). While I'm sure there are plenty
of stories about unpleasant experiences with Oracle Clusterware's method of
node eviction, I'd submit that if you look hard enough, you're always bound to
find someone with a bad experience about something that you think is very
solid.
The short answer to your question is that I think node eviction is a rare
occurrence on most "normal" configurations.
Dan
----- Original Message ----
From: John Hallas <john.hallas@xxxxxxxxxx>
To: dannorris@xxxxxxxxxxxxx; ujang.jaenudin@xxxxxxxxx; Peter McLarty
<peter.mclarty@xxxxxxxxxxxxxxxxxx>
Cc: oracle-l@xxxxxxxxxxxxx
Sent: Wednesday, December 5, 2007 8:21:09 AM
Subject: RE: oracle rac 10g and OS clusterware.
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Good response
Dan. How often does node eviction take place on a ʽnormalʼ
configuration (if there is such a thing).
PS I came
across an excellent presentation of yours this morning on HA options for Oracle
http://www.dannorris.com/wp-content/uploads/2007/11/ha-options-for-oracle-db-oow2007-slides.pdf
John
From:
oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf
Of Dan Norris
Sent: 05 December 2007 03:32
To: ujang.jaenudin@xxxxxxxxx; Peter
McLarty
Cc: oracle-l@xxxxxxxxxxxxx
Subject: Re: oracle rac 10g and OS
clusterware.
Ujang,
Oracle Clusterware 10g will always handle node fencing (aka eviction) by
rebooting one or more nodes. Oracle didn't have it's own cluster manager
software for most platforms on 9i. So, if your customer was on a platform where
Oracle didn't have a cluster manager of its own (it only had Linux and
Windows), then building the RAC cluster would have required some 3rd party
software. Some of the 3rd party cluster managers used different schemes to
fence nodes from the cluster. Many of them used I/O fencing which was somewhat
less disruptive in that it didn't require a node reboot, but required more
proprietary interfaces to be used to access and manage storage.
The answer to your question is that it depends. You will always have to have
Oracle Clusterware if you're building a 10g cluster. However, if you
additionally use a 3rd party clusterware (one that uses I/O fencing instead of
reboots to handle node eviction), Oracle Clusterware will not handle cluster
membership and therefore won't impose its "reboot the other node"
scheme of node eviction. I should mention that I believe this is true in most
cases, but not all cases.
If you use just Oracle Clusterware (which is the only requirement and handles
all cluster management needs albeit with using node reboots to evict them from
the cluster), you'll be subject to node reboots if node eviction is required.
See Kirk McGowan's post on Oracle Clusterware's node eviction methods at
http://blogs.oracle.com/kmcgowan/2007/08/09#a13
for some additional insight.
Dan
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