RAC Investigation on Low-Memory Linux

September 2nd, 2010 § Leave a Comment

Back in the Oracle 9i days, I was one of those people who got on eBay to buy firewire PCI cards and disks that could do non-exclusive login.  Remember that?  The first time a little test cluster could be cheap enough for the home enthusiast?  I still have the parts in my closet.

Of course, we all know what happened after that – virtualization.  It didn’t take long before my home-built test clusters were running on VMware.  (Personally, I think that virtualization really started because of those NES and SNES emulators.  Most great achievements start with a geek who wants to play more video games.)  There are lots of people now who run RAC on virtual environments and it’s easy to find tutorials on the web for many different OS and VM combinations.

Low-Memory Linux

Something I haven’t seen many other people do is RAC with a very small memory configuration.  Like 760M of memory per server. (!)  Of course you’d only do this for a hobby setup – never on a system where you want any kind of support.  But I’m kinda cheap… and running RAC on these small VMs means that I don’t have to go buy an expensive new home computer.  My current gateway laptop with Vista Home does the job quite nicely!

10.2 and 11.1 RAC will install and run on servers with 760M of memory. But things were a little unstable at first. Now I’m the curious type… I like to fiddle with things… so I investigated a little bit.

Basic Unix Investigation

There are two basic investigation scenarios:

what happened in the past My main tool is sar (System Activity Reporter). Or Java-based ksar on my desktop – it gets data via ssh and graphs it.
what is happening now My starting point is vmstat and top. To dig a little deeper, I might then use other tools like ps, free, iostat or netstat.

In this particular case, I noticed pretty quickly from the top utility that one process was consuming over 30% of the system’s memory!  » Read the rest of this article «

DBCA Missing – Oracle 11.2 ASM/Grid

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Oracle provides three ways to manage ASM: (1) through SQL, (2) through the web-based database console or grid control, and (3) through the server-based java GUI tool DBCA.  These are your choices for adding storage, replacing a disk, growing a volume, etc. But if you’re an experienced DBA who recently started playing with 11gR2 ASM, [...]

Michigan OakTable – Illinois Visitors?

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ASM Mirroring – No Hot Spare Disk

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Five Reasons to do RAC Attack at Collaborate

April 6th, 2009 § 0

Last week Dan broke the news that we’re bringing RAC Attack back to Collaborate! We’ve run this workshop several times now: it’s gotten better every time and we’ve always received overwhelmingly positive feedback. This is going to be a great workshop in Orlando that you don’t want to miss! A Short History We first ran [...]

ASM Negative Free Space

March 17th, 2009 § 3

In the last post I showed mathematically how ASM calculates the free usable space that it displays. However one of the first questions I received after presenting that internally was from someone concerned about all of the unusable space being saved just in case we lose a disk. (In my worked example it was 1/6 [...]

ASM Space Calculations and Hot Spares

March 12th, 2009 § 1

This is quick and dirty. I hope to get a more polished write-up of what it means and how it works, but since I’m so busy right now I don’t know if I’ll get to it soon. In the meantime someone just might find this useful or informative so I’m just going to put it [...]