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Published: 09 March 2011

Currently I reinstalled my Samsung Galaxy S (with insanity 6.3) and came across "an error occured while downloading your recovery." when trying to flash clockworkmod recovery. With installing a superuser version from the market and reinstalling clockworkmod my problem seems to be solved. There seems to be a bug in the superuser app I was using previously.

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Published: 04 November 2010

I recently installed a usb-harddisk on my server and mounted it on a guest with virt-manager. The performance was very bad, i had 50Kbyte when testing with hdparm.

I remounted it in virt-manager as IDE drive instead of USB-Drive and voila i had full performance again. It seems that the USB-drive mounting is a bit bugged.

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Published: 04 November 2010

I am using KVM for a while now and reinstalled my XEN-Server. I have to mention it's not the same hardware. XEN was on a 2 year old Server with 4G memory and Debian Lenny32, KVM is on a 6 months old 8G memory Server with Debian Squeeze. So i have a bit better hardware and a 64bit System on KVM.

I like that KVM is out-of-the-box working with virsh/virt-manager the performance improvement is enormous, especially with 64MB-RAM systems like I use for my wiki. I use LVM for the guest-disks (I did it even for the XEN-guests) and compared to use files it's even a huge performance improvement.

The only thing that's easier in XEN is that you can mount the guest-partitions and can access them directly in KVM you need to use kpartx (not hard but one step more) to achieve this.

I started to move to KVM because it seems as XEN development slowed down and there is much more development activity and support for KVM. I think that was a good decision.

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Published: 24 October 2010

I recently needed to install a Oracle 11g Database on Debian, and wrote down the notes here. Please send me a message

if i missed a step or something is easier to achieve than I did.

install mandatory packages

some packages are probably not necessary, I put them together from old notes from me and several weblinks if you know which are not necessary send me a list and i will correct it

apt-get install binutils autoconf automake bzip2 gcc less libc6-dev make libstdc++5 unzip zlibc build-essentials libaio1

!!!doxygen reported as not needed by Tobia, tx for this! Also watch his comment if you use OpenVZ!

x-terminal

I chose fluxbox but you can also take anything else like xterm, gnome, kde….

apt-get install fluxbox

prepare user and groups

groupadd oinstall
groupadd dba
useradd oracle -m -d /home/oracle -g oinstall -G dba -s /bin/bash
passwd oracle

check environment

there are several kernel parametersw that have to be changed to succesfully install the database, here is a script that helps you to determine them

echo "sem: ";echo "min 250 32000 100 128"; echo "is " `cat /proc/sys/kernel/sem`; echo; \
echo "shmall: ";echo "min 2097152"; echo "is " `cat /proc/sys/kernel/shmall`; echo; \
echo "shmmax - should be able to hold the SGA - max 4G-1byte: ";echo "is " `cat /proc/sys/kernel/shmmax`; echo; \
echo "shmmni: ";echo "min 4096"; echo "is " `cat /proc/sys/kernel/shmmni`; echo; \
echo "file-max: ";echo "min 6815744"; echo "is " `cat /proc/sys/fs/file-max`; echo; \
echo "ip_local_port_range: ";echo "min/max 9000  65500"; echo "is     " `cat /proc/sys/net/ipv4/ip_local_port_range`; echo; \
echo "rmem_default: ";echo "min 262144"; echo "is " `cat /proc/sys/net/core/rmem_default`; echo; \
echo "rmem_max: ";echo "min 4194304"; echo "is " `cat /proc/sys/net/core/rmem_max`; echo; \
echo "wmem_default: ";echo "min 262144"; echo "is " `cat /proc/sys/net/core/wmem_default`; echo; \
echo "wmem_max: ";echo "min 1048576"; echo "is " `cat /proc/sys/net/core/wmem_max`; echo; \
echo "aio-max-nr: ";echo "max 1048576"; echo "is " `cat /proc/sys/fs/aio-max-nr`; echo;

change necessary parameters

you have just to change the parameters that don't fit, but feel free to set them all to the minimum with this script

echo "kernel.sem = 250 32000 100 128" >> /etc/sysctl.conf
echo "kernel.shmall = 2097152" >> /etc/sysctl.conf
# !!!! needs to fit YOUR SGA (=main memory for database, be sure to have enough ram for PGA etc.)!!!!
echo "kernel.shmmax = 1200000000" >> /etc/sysctl.conf
#echo "kernel.shmmni = 4096" >> /etc/sysctl.conf
echo "fs.file-max = 6815744" >> /etc/sysctl.conf
#echo "net.ipv4.ip_local_port_range = 1024 65000" >> /etc/sysctl.conf
echo "net.core.rmem_default = 262144" >> /etc/sysctl.conf
echo "net.core.rmem_default = 262144" >> /etc/sysctl.conf
echo "net.core.rmem_max = 4194304" >> /etc/sysctl.conf
echo "net.core.wmem_default = 262144" >> /etc/sysctl.conf
echo "net.core.wmem_max = 1048576" >> /etc/sysctl.conf
echo "fs.aio-max-nr = 1048576" >> /etc/sysctl.conf

change some limits

also some limits have to be set

echo "oracle soft nproc 2047" >> /etc/security/limits.conf
echo "oracle hard nproc 16384" >> /etc/security/limits.conf
echo "oracle soft nofile 1024" >> /etc/security/limits.conf
echo "oracle hard nofile 65536" >> /etc/security/limits.conf

create directories

I prefer to separate software, database files and recovery files so i put them in /u01 /u02 /u03

mkdir -p /u01/app/oracle
mkdir -p /u02/oradata
mkdir -p /u03/flash_recovery_area
chown -R oracle:oinstall /u01 /u02 /u03
chmod -R 775 /u01 /u02 /u03

NOTE: seems they just say “recovery_area” or even “fast_recovery_area” now to the “flash_recovery_area”
additional steps

These steps prevent errors when the installer links some libraries

ln -s /usr/bin/awk /bin/awk
ln -s /usr/bin/basename /bin/basename

finish preparations

reboot

== call the installer But before calling the installer check with above script if the kernel parameters are fine now

su oracle
/pathtoinstallfileshere/database/runInstaller -ignoreSysPrereqs

installer

The installer should guide you through each step in simple and advanced mode. When the requirements are checked you can savely bypass the warnings, because not everything can be checked on an unsupported ;-) environment.

!!!I really want to keep this up-to-date so please send me a note if i missed something or something is easier to handle than i did it!!!

Errors that can happen and how to bypass them

java exception when calling the installer

happened at my side because I installed it over vnc This should help:

xhost localhost

Error in invoking target 'install' of makefile ins_ctx.mk

seems to be a problem with a newer? glibc version in the make.log file you should find something like

warning: libstdc++.so.5, needed by /u01/app/oracle/product/11.2.0/dbhome_1/ctx/lib//libsc_fa.so, not found

simply install libstdc++5 apt-get install libstdc++5

Details

Published: 25 September 2010

Details

Published: 25 August 2010

Some time ago (after noticing my stuff was not working anymore ), I wrote a Utility Class for the Amazon Product API. I now published it as part of my new Amazon Tools project, that can be downloaded as complete class with examples here. It's licensed under Simplified BSD License.

	/**
	 * signs the request Url for the Amazon API  
	 * @param str      pUrl 			   unsigned Url  
	 * @param str      pSecretAccessKey                it's a hash to sign the Url, 
         *                                                 you get that from the Amazon-Partner network
	 * 						   together with your AccessKey 
	 * @return 		                           signed Url
	 */
	function &signRequestUrl($pUrl,$pSecretAmazonHash){
	    // retrieve Parameter from urls 
	    $arrUrlParts    = parse_url($pUrl);
	    $vParams		= $arrUrlParts['query'];
  	    // parameters are separated by & so we put them in 
            // another array, in there are values like "aa=bb" "xx=yy"	    
            $arrParams		= explode('&',$vParams);
	    // loop and put pair/values in array
	    foreach($arrParams as $vPair){
	    	// easy separating of the name/val by using explode
	    	$arrPair 	   = explode('=',$vPair);
	    	$arrParamsSort[$arrPair[0]] = $arrPair[1];  
	    }
	    // Timestamp needed if there is none present
	    $arrTemp = array_change_key_case($arrParamsSort,CASE_UPPER); 
	    // format from amazon-docs
	    if (empty($arrTemp['TIMESTAMP'])){
	    	$arrParamsSort['Timestamp'] = gmdate('Y-m-d\TH:i:s\Z');
	    }
	    // sort the array, needed to make the Url canonical
	    ksort($arrParamsSort);
	    // canonical means that the parameters are sorted 
            // so it's easier to check if urls are different
	    $vCanonicalString = '';
	    foreach ($arrParamsSort as $vKey => $vVal){
		// rawurlencode => 5.3 should be RFC 3986 compliant 
		// for php versions below this should do the job  
		$vNewVal = str_replace('%7E','~', $vVal);
	    	$vCanonicalString = $vCanonicalString.$vKey.'='.rawurlencode($vNewVal).'&';
	    }
	    // remove last &
	    $vCanonicalString = rtrim($vCanonicalString,'&');
	    // from he amazon docs
	    $vSignString	  = "GET\n".strtolower($arrUrlParts['host']).
            "\n".$arrUrlParts['path']."\n".$vCanonicalString;
	    // generate the hash from the request
	    $vSignature		  = hash_hmac('sha256',$vSignString,$pSecretAmazonHash,true);
	    // and base64 encode it
	    $vSignature 	  = rawurlencode(base64_encode($vSignature));
	    // rebuild the url with the signature
	    $vRet = $arrUrlParts['scheme']."://".$arrUrlParts['host'].
            $arrUrlParts['path']."?".$vCanonicalString."&Signature=".$vSignature;
	    return $vRet;
	}
 

Details

Published: 14 May 2010

I was looking for a solution to use multiple desktops in Windows7 like its possible on Linux since.... ever?

To use multiple desktops is very convenient if you develop software, a lot of application are often just used once ore twice a day but you have to tab through them very often. There seems to be no solution from Microsoft, and i could not really find any other good solution, until i ran over Virtual Dimension. The last update was in 2005. I was very skeptical because the software was not maintained for over five years. But... this is why i write this article its GREAT STUFF!. Why?

1. it installs pretty fast and is pretty small (~400k)
2. very easy to configure, intuitive handling
3. possible to use drag and drop of the applications (you can move your applications between the desktops

I dont know how it can be possible that somebody writes software that works for five years on different OS versions, but its incredible.

I hope Francois Ferrand will continue to work on this project.

Details

Published: 10 May 2010

1

java.security.AccessControlException: 
access denied (java.lang.RuntimePermission accessClassInPackage.sun.java2d)

Details

Published: 08 May 2010

If you get that error when invoking the Oracle-Forms Layout-Editor and you are sure the naming of the bean and also the FORMSxx_BUILDER_CLASSPATH variable is set correctly, then you should check with which java-version your bean is compiled. To display it correctly in version 10.x you need JDK 1.4.2_06 or lower. I don't know which version you need for version 11, please comment if you have any infos about that.

Details

Published: 24 March 2010

If you programmatically modify a window by using SET_WINDOW_PROPERTY a WHEN-WINDOW-RESIZED event should be triggered. If in the meantime a message is dispatched by a bean (WHEN-CUSTOM-ITEM-EVENT) the WWRSZ is NOT processed. It seems to be a matter of timeing how long the message to the server takes because it does not always occur (of course same code.... nothing changed...).

Hopefully i can reproduce it on a minimal form for the ORACLE-support.