Monday, June 28, 2010

Oracle VirtualBox 3.2 features for the database

I haven't updated my blog in a while, so I thought what better way to get things going again than post my latest interactions with VirtualBox.  Ever since the Oracle branded version of VirtualBox rolled out with version 3.2 on May 18, there have been many new features and improvements.
Prompted by last week's "What's new in 3.2?" Oracle VirtualBox Webinar by Andy Hall and Achim Hasenmueller of the VirtualBox team I decide to list my favorite new features - Page Fusion, Support for  deleting snapshots while running a guest and disabling host I/O cache.  I listed these features as my fave because of their direct relationship with running Oracle Databases in  a VirtualBox environment and RAC in particular.  (I'll post a blog about my new Oracle 11gR2 RAC on VirtualBox in the next installment).  Page Fusion increases VM guest density via memory de-duplication.  In a nutshell it gives you the ability to run more VMs with less RAM. Snapshots are a pretty handy feature especially when it comes to building complex environments such as Oracle RAC.  Multiple snapshots enable me to go back and forth in time - so 8 hours of configuration is not lost if I decided I wanted to make a configuration change.  However, it does come at a cost - disk space.  Deleting snapshots helps free up some of this space and it helps that you can do this while the VM is running.  I must admit that I had some trouble while attempting this after the first 3.2 update.  I lost several disks while attempting this.  I theorized this to be due to a bug which happened when pre-existing 3.2 snapshots where deleted.  So this 'bug' was filed but I haven't heard if any fixes were provided yet.  All in all it works great.  Next up, host I/O caching has been the default method used for VirtualBox.  Writes by the guest OS are cached by the host which potentially increases speed.  In some situations however, host I/O caching causes slow down on the host and causes the guest VM to hang.  I experienced this while building my first EL5 guest on VirtualBox on Ubuntu linux host.  You can disable host I/O caching for each controller by unchecking the box next to 'enable host I/O cache'.
Oracle has certainly continued to build on what was already a great product.  It is not without faults however, since there have been several complaints about stability since version 3.2.
As of this post the general maintenance release 3.2.6 is available and I expect this to resolve many of the initial problems of the 3.2 release.

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