Oracle: Unbreak my Linux Heart

We had a strange issue during Oracle WebLogic development yesterday. Setting up a secure connection between a client and the WebLogic Admin server took really long on our shiny new hardware (Dell R710) compared the older servers (Dell 2950). After we made sure everything was exactly the same, people started to blame C1 and C1E states and other powersave or cpu throttling measures. However, given the different in setup times (2-6 sec vs 50-90 sec), I suspected it to be something else. Throttling down from 2.23 GHz to 1.6 GHz cannot cause such a great difference. Or at least be unlikely. Lo and behold, it turned out to be related to the seeding of the random number generator in Java. Normally this is linked to /dev/random but can be sped up by using /dev/urandom , which uses some entropy of your system. Still, the urandom device, while faster, still caused a 20-fold difference. As a workaround, you can tell your JVM which seed generator to use and prevent JVM from waiting or looking or ...

Robin at yo61.com found a great and handy way to discover the MAC addresses of the embedded NICs of your Dell (PowerEdge) servers. Instead of going through DRAC, logging in, starting Java, etc. you can also get the same using the RAC command line interface: racadm racdump. Read the article on yo61.com for complete details. Excellent! If only I could find a similar command for my 500 PE2950 servers with DRAC5...

Slashdot : "Oracle Corporation (NASDAQ: ORCL) and Sun Microsystems (NASDAQ: JAVA) announced today they have entered into a definitive agreement under which Oracle will acquire Sun common stock for $9.50 per share in cash. The transaction is valued at approximately $7.4 billion, or $5.6 billion net of Sun's cash and debt." Note: Oracle's server is currently Slashdotted. LOL

After 64 bit Flash from Adobe, 64 bit Wine, we now also get 64-Bit Java For Linux ! This 64-bit plug-in is coming as part of Java SE 6 Update 12 Build 02, which was released last Friday. This 64-bit compatibility is for both Linux and Windows, while Sun's own Solaris operating system will pick up the 64-bit support once it has a 64-bit version of Firefox. Yeah, everyone's catching up, finally!

Ran across an interesting tidbit on the Dell PowerEdge mailing list again. There was a question regarding the web server used in Dell's OpenManage . It turns out to be a formerly commercial web server written in Java that has since gone open source: Servertec .

Found a useful post on the Dell PowerEdge mailing list . There was a discussion to get DRAC5 and Firefox working, especially on Linux but for Windows its also useful. Mark Watts finally gave the correct instructions . Reports are that FF 1.5 also works but 3.x still does not. [Update: When using DRAC v1.40 , there are supposed to be Java plugins for Firefox 3.x] [Update2: I can confirm that DRAC5 v1.40 works fine with FF2+ in Windows and Linux. Haven't tried OS X yet.]

I recently had a question about Linux that created more questions the longer I thought about it. The question was: "Given the app doesn't care, would you recommend 32 bit or 64 bit Oracle Linux for a server?" Driver compatibility plays a part, as does the amount of RAM the app needs. If you need more than 4 GB of RAM, you'll have to use a 64bit kernel... or do you...? I'm still not absolutely sure about it as information is a bit ambiguous. While some say you cannot allocate more than 3.7 GB of RAM to any one process on a 32 bit machine, using PAE , others say to just check free -m or vmstat . Red Hat lists /proc/meminfo as a good source of information and explains what you see there. All said and done, I still don't know for sure. I have a VM with 4 cores and 8 GB of RAM, and it says: [root@server ~]# uname -a Linux server 2.6.9-55.0.0.0.2.ELsmp #1 SMP Wed May 2 14:59:56 PDT 2007 i686 i686 i386 GNU/Linux [root@server ~]# cat /proc/meminfo MemTotal: 805...

Since we are virtualizing many of our Linux servers, this post was of interest to us: "VMmark 1.0 utilized only 32-bit workloads, which was a reasonable mix when the benchmark was first defined roughly three years ago. However, 64-bit applications and OSes are becoming much more prevalent and we need the ability to characterize this more complex reality. To address this, [ for vmware 1.1 ] we have transitioned three of the VMmark workloads - Java server, database server, and web server - to 64-bit. In order to maintain comparability with the existing version 1.0 results, we have retained the underlying virtual hardware definitions and load levels for each workload." This will let us benchmark our specific ESX host setup and test Oracle Linux VM servers under various settings...