Category Archives: Xen

RAC in KVM is possible without iSCSI

(This post is for Jerry. He will know when he reads it)

I have been a great supporter of many flavours of virtualisation and my earliest experience with Xen goes back to Oracle VM 2 which was based on RHEL 4 and an early version of Xen. Why am I saying this? Because Xen is (was?) simple and elegant. Especially for building RAC systems: paravirtualised Linux was all you needed, and a dual-core machine: Xen is very lightweight even though recent achievements in processor architecture (nested page tables, single root IO virtualisation, others) make it more desirable to use hardware virtualisation with paravirtualised drivers. This is what this post is about!

Shared storage in Xen

As you know you need shared block devices for RAC for voting disks, OCR, data files, redo logs, the lot. In Xen that’s as straight forward as it gets:

disk = [

The “w!” means the block device is shared. Simple. Make the file available to the second RAC node and you are done.

In 2009 (yikes!) I ask the question if you could have RAC on KVM with the same technique. Who would have known then that Karl would be a colleague on day? Fast forward a few years and I have implemented such a solution. And it works in the lab. Continue reading

Availability Infrastructure & Management SIG March 14th 2012

I am proud to be able to speak at the first instalment of the Availability, infrastructure and management SIG on March 14th in  the London City office.

The event is announced on the UKOUG website here:

Unfortunately I will be between you and lunch! I hope that works out, and I don’t overrun.

I am going to demonstrate my (little) knowledge of Oracle Enterprise Manager 12.1. I looked at it for one of my customers and came to like it. As it is very different from the previous versions of the product, a more closely focused session seems appropriate. An Internet connection permitting, I am going to demonstrate navigation through the new interface, self update, target discovery and if time permits, I will patch a single instance HA environment (also known as Oracle Restart).

If all demos work this could be quite an entertaining sessions, questions are welcome!

Did you know the cluvfy healthcheck?

While I was performing a three day seminar recently in Switzerland I came across this new option in cluvfy.

Normally you’d run cluvfy in preparation of the installation of Grid Infrastructure or a set of RAC binaries to ensure everything is ready for the next step in the RAC install process. Beginning with, there is another option that’s been sneaked in without too much advertisement: the healthcheck.

Part of the “comp” checks, it takes the following options:

cluvfy comp healthcheck [-collect {cluster|database}] [-db db_unique_name] [-bestpractice|-mandatory] [-deviations] [-html] [-save [-savedir directory_path]

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Getting started with Xen virtualisation on Ubuntu 11.10

After a long time and lots of problems I decided to abandon openSuSE 11.4 and its xen implementation in favour of the PVOPS kernel and a different distribution.

It’s been difficult to choose the correct one for me, for now I’m working with Ubuntu 11.10. One reason is that it’s said to be user friendly, and highly customisable. It comes with all the right ingredients for running different hypervisors, including my favourite: xen.

Important update! See “Security” below.

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Move the EM12c repository database

I have made a little mistake creating a RAC database for the OEM 12c repository-I now need a little more lightweight solution, especially since I’m going to do some fancy failover testing with this cluster soon! An single instance database without ASM, that’s what I’ll have!

Now how to move the repository database? I have to admit I haven’t done this before, so the plan I came up with is:

  1. Shut down the OMS
  2. Create a backup of the database
  3. Transfer the backup to the destination host
  4. Restore database
  5. Update OEM configuration
  6. Start OMS

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The tale of restoring the OCR and voting files on Linux for RAC

As part of a server move from one data centre to another I enjoyed working in the depths of Clusterware. This one has been a rather simple case though: the public IP addresses were the only part of the package to change: simple. One caveat though was the recreation of the OCR disk group I am using for the OCR and 3 copies of the voting file. I decided to reply on the backups I took before the server move.

Once the kit has been rewired in the new data centre, it was time to get active. The /etc/multipath.conf file had to be touched to add the new LUNs for my +OCR disk group. I have described the processes in a number of articles, for example here:

A few facts before we start:

  • Oracle Enterprise Linux 5.5 64bit
  • device-mapper-multipath-0.4.7
  • Grid Infrastructure (actually it is Oracle Database SAP Bundle Patch
  • ASMLib

I have already described how to restore the OCR and voting files in in “Pro Oracle Database RAC 11g on Linux”, but since then the procedure has changed slightly I thought I’d add this here. The emphasis is on “slightly”. Continue reading

Installing Oracle Enterprise Manager 12c on OL 5.7

I have been closely involved in the upgrade discussion of my current customer’s Enterprise Managers setup from an engineering point of view. The client uses OEM extensively for monitoring, alerts generated by it are automatically forwarded to an IBM product called Netcool.

Now some of the management servers are still on in certain regions, and for a private cloud project I was involved in an 11.1 system was needed.The big question was: wait for 12.1 or upgrade to 11.1?

So to cut a long story short I have been very keen to get to the OEM 12c beta programme, but unfortunately wasn’t able to make it. Also, I wasn’t at Open World this year which means I didn’t get to see any of the demos. You can imagine I was quite curious to get my hands on it, and when it has been released a few days ago I downloaded it to my lab machine. I created a new domU for the database- plus latest PSU and another one for the management server. I assigned 2 CPUs each, the database server got 2G of memory while the OMS received 8.Don’t take this as a recommendation though, it’s only for lab use! I wouldn’t use less than 24G of memory for a production management server, and it would obviously follow the MAA recommendations and be installed behind an enterprise grade load balancer etc. Needless to say I’d use RAC+Data Guard for the repository database.

Continue reading