Transferring Linux install media to USB thumb drive

Optical drives are nowadays less common on laptops which makes making bootable install medias a little easier. Yes, easier by requiring you to use USB thumb drives. There are different ways to achieve what you want and here is couple of examples how to transfer Linux install media to USB thumb drive on Windows and Mac OS X.

First you need to download the install media of your choice as ISO image which you want to transfer to your USB thumb drive. In theory you need a media which is meant for USB thumb drive or is a Hybrid ISO image but practically all modern distributions' media are Hybrid ISO images.

Windows

Plug in the USB thumb drive and format it with FAT32 file system

Download UNetbootin and transfer ISO content to USB thumb drive using UNetbootin.

  1. Select Diskimage and click the ". . ." button to find and open the ISO file. Make sure Type is USB drive and the Drive letter is what your Windows detect and click OK. Your ISO content will be copied to USB thumb drive.
  2. Next you also need to copy the ISO file that you used with UNetbootin to the root of the USB thumb drive, e.g. the ISO file should be F:\linuxmint-16-cinnamon-dvd-64bit.iso

Now you can proceed to boot up the machine that you want to install with e.g. Linux Mint 16.

Linux

Creating bootable USB thumb drive in Linux is much simpler. You just need install media which is meant for USB thumb drive or is a Hybrid ISO image. With hybrid images, you can simply write the content of the ISO and make a bootable USB stick which can install Linux by using the 'dd' command.

You just need to have the ISO image and one command:

$ sudo dd bs=4M if=linux-image.iso of=/dev/sdX oflag=direct

Where sdX is the device where your USB thumb drive is, e.g. sdb. If your system doesn't support 'oflag=direct', you can just leave it out as it is simply intended to speed up the process a bit. If you leave the bs-option off the default will be 512 bytes and takes forever.

Mac OS X

OS X's DiskUtil can't burn ISO images to USB and gives "Invalid argument" but fortunately just like with Linux also Mac OS X makes things easy for you. You just need the install media which is meant for USB thumb drive or is a Hybrid ISO image. With hybrid images, you can simply write the content of the ISO and make a bootable USB stick which can install Linux by using the 'dd' command.

$ dd if=linux-image.iso of=/dev/rdiskX bs=8192

Where rdiskX is the device where your USB thumb drive is, e.g. rdisk1. You can see the device (disk identifier) from DiskUtility.app by selecting your USB stick and checking the Device section.

It's useful to notice that on OS X you can use the '/dev/rdiskX' device which stands for raw disk and is much faster than the block level device '/dev/diskX' which is buffered and where data undergoes extra processing. For example rdiskX gives "823132160 bytes transferred in 625.470137 secs (1316022 bytes/sec)" and diskX gives "823132160 bytes transferred in 1296.675998 secs (634802 bytes/sec)".

If you get an error e.g. "dd: /dev/rdisk2: Resource busy" then you have to make sure the Mac OS X isn't using it and thus unmount it's partitions. Open the DiskUtility.app, and on your USB hard drive, unmount any of it's partitions. Do not eject the USB hard drive.

Do a clean install of Windows 8 with an upgrade key

There are times when you have to do a clean install of your Windows 8 but if you have just an upgrade key you need to make couple of extra hoops before you can activate the new install. The upgrade key doesn't prevent you installing to a clean disk but when you try to activate, you get an error 0x8007007B, saying your product key can only be used for upgrading. Another fine example how Microsoft makes things complicated for legitimate users.

Fortunately there's a way to fix that issue as Lifehacker's article tells:

  • Open the Registry Editor (Win + R, type regedit).
  • Navigate to "HKEY_LOCAL_MACHINE/Software/Microsoft/Windows/CurrentVersion/Setup/OOBE/" and change the MediabootInstall key's value from 1 to 0.
  • Open the Command Prompt (Win + R, type cmd). Right-click on the Command Prompt icon and run it as an administrator.
  • Type slmgr -rearm and press Enter.
  • Reboot Windows.

After that is done and you get back into Windows, you should be able to run the Activation utility and activate Windows as normal, without getting an error.

Apparently you can also call Microsoft Support and they will walk you through the proper way doing this because they understand you may have bought a new drive. There is a dialog you can get to in system tools where it will ask you for a numerical code. The support personnel will give you the number, you click "OK" after typing it in, then go the activation again and it works. This process is likely doing the work around mention above, but through an approved administrative process.

By the way, restarting Windows 8 is most easily done by left-clicking once on an empty spot on the desktop and holding Alt + F4).

Monitoring Java EE application with JavaMelody

Software development is much more than just coding application by requirements and deploying it to production as the real work really starts after it has been shipped: maintenance, improvements and problem solving. And for that it's good to have some data. It's said "if you can't measure it, you can't improve it" and in ideal situations you plan for measuring your app but often you have to do it in production to detect and diagnose performance problems. There are different ways to measure a Java EE application and one good tool to achieve performance and monitoring statistics is Javamelody which has low overhead, is non-intrusive, informative and simple to setup but still very capable.

"If you can not measure it, you can not improve it." - Lord Kelvin

Application performance can be measured by two main methods: computational resources used by the application and the performance as seen by a user of the application. By measuring these quantities we get an empirical performance baseline of the application which then can used to detect changes in performance. By using performance monitoring, which is an act of non-intrusively collect or observe performance data from running application, we get measurements to identify or isolate potential issues from real operation of an application without having a severe impact on runtime responsiveness or throughput.

There are different ways to achieve performance and monitoring statistics and it's useful to plan for measuring application's performance while still in development as later on you surely want to know how it is performing. You can do it by leveraging different JMX-based tools like Metrics and Servo but if you didn't really plan for it you still have choices. You can use tools like standard JDK tools (jconsole, jstat, jmap, jstack, hprof) for low level JVM monitoring or some monitoring application like Javamelody. And as time is always scarce in development it's useful to deploy a tool like JavaMelody which provide quick and easy access to performance monitoring. But if you are interested of some narrow focus measurement you're better of with some custom tool.

Monitoring with JavaMelody

JavaMelody is an open source (LGPL) application to monitor Java or Java EE application servers in QA and production environments. It is a tool to measure and calculate statistics on real operation of an application depending on the usage of the application by users and is mainly based on statistics of requests and on evolution charts which can be viewed on the current day, week, month, year or custom period. The statistics can be viewed on a HTML page and sent as PDF reports by email.

JavaMelody lists the following use cases:

  • It allows to improve applications in QA and production
  • Give facts about the average response times and number of executions
  • Make decisions when trends are bad, before problems become too serious
  • Optimize based on the more limiting response times
  • Find the root causes of response times
  • Verify the real improvement after optimization

Setting up

Setting up JavaMelody is quite easy and the needed steps are covered in User guide. Integrating JavaMelody to your application can be done in less than 10 minutes, by automatic discovery of environment: it only requires to copy 2 jar files and to add 10 lines in a xml file. But for more detailed and wider measurements you need couple more lines to xml files and here are the changes I made for our Wicket, Spring, JPA, Hibernate -Java EE project.

JavaMelody and dependencies

Getting JavaMelody and it's dependencies is easy with Maven2 and you just need to add javamelody-core and if you want to have PDF reports also iText in your pom.xml:

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<!-- javamelody-core -->
<dependency>
	<groupId>net.bull.javamelody</groupId>
	<artifactId>javamelody-core</artifactId>
	<version>1.45.0</version>
</dependency>
<!-- itext, option to add PDF export -->
<dependency>
	<groupId>com.lowagie</groupId>
	<artifactId>itext</artifactId>
	<version>2.1.7</version>
	<exclusions>
		<exclusion>
			<artifactId>bcmail-jdk14</artifactId>
			<groupId>bouncycastle</groupId>
		</exclusion>
		<exclusion>
			<artifactId>bcprov-jdk14</artifactId>
			<groupId>bouncycastle</groupId>
		</exclusion>
		<exclusion>
			<artifactId>bctsp-jdk14</artifactId>
			<groupId>bouncycastle</groupId>
		</exclusion>
	</exclusions>
</dependency>

Monitoring application

JavaMelody needs just a monitoring filter before the description of webapp's servlet in WEB-INF/web.xml or not even that as described in the User guide. But usually you want a little bit more than the minimum 10 additional lines in web.xml.

By adding the customResourceFilter you get customized look & feel, you can exclude some urls from statistics with url-exclude-pattern regular expression pattern, eamil-parameters are for weekly reports and by including monitoring-spring.xml you can monitor DataSource with a Spring post-processor and objects initialized with Spring.

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...
<context-param>
	<param-name>contextConfigLocation</param-name>
	<param-value>
		classpath:net/bull/javamelody/monitoring-spring.xml
		classpath:applicationContext-service.xml
		classpath:applicationContext-persist.xml
		classpath:applicationContext-web.xml
		classpath:applicationContext-security.xml
    </param-value>
</context-param>
 
<!-- Must be defined before javamelody filters -->
<filter>
	<filter-name>springSecurityFilterChain</filter-name>
	<filter-class>org.springframework.web.filter.DelegatingFilterProxy</filter-class>
</filter>
<filter-mapping>
	<filter-name>springSecurityFilterChain</filter-name>
	<url-pattern>/*</url-pattern>
</filter-mapping>
 
<!--====================== Monitoring ===================================-->
<!-- Custom CSS -->
<filter>
	<filter-name>customResourceFilter</filter-name>
	<filter-class>net.bull.javamelody.CustomResourceFilter</filter-class>
	<init-param>
		<param-name>monitoring.css</param-name>
		<param-value>/styles/monitoring.css</param-value>
	</init-param>
</filter>
<filter-mapping>
	<filter-name>customResourceFilter</filter-name>
	<url-pattern>/monitoring</url-pattern>
</filter-mapping>
<!-- Monitor filter -->
<filter>
	<filter-name>monitoring</filter-name>
	<filter-class>net.bull.javamelody.MonitoringFilter</filter-class>
	<init-param>
		<param-name>storage-directory</param-name>
		<param-value>logs/monitoring</param-value>
	</init-param>
	<init-param>
		<param-name>url-exclude-pattern</param-name>
		<param-value>(/images/.*|/js/.*|/styles/.*)</param-value>
	</init-param>
	<init-param>
		<param-name>admin-emails</param-name>
		<param-value>first.last@example.com</param-value>
	</init-param>
	<init-param>
		<param-name>mail-session</param-name>
		<param-value>MailSession</param-value>
	</init-param>
	<init-param>
		<param-name>mail-periods</param-name>
		<param-value>week,month</param-value>
	</init-param>
</filter>
<filter-mapping>
	<filter-name>monitoring</filter-name>
	<url-pattern>/*</url-pattern>
</filter-mapping>
<listener>
	<listener-class>net.bull.javamelody.SessionListener</listener-class>
</listener>
...

Spring Security config

For restricting the access to monitoring statistics I added the following to the Spring Security's applicationContext-security.xml. There are also other options for security. The key point here is to make sure, that the monitoring-filter in web.xml (above) is defined after the Spring Security filter chain.

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<http auto-config="true" use-expressions="true">
    ...
    <intercept-url pattern="/monitoring/**" access="hasRole('ROLE_ADMIN')" />
	<intercept-url pattern="/**"
			access="hasAnyRole('ROLE_ADMIN, 'ROLE_USER'')" />
</http>

Monitoring SQL and datasources

For monitoring datasources and SQL I just added jndi-lookup to applicationContext-persist.xml. Other options to enable JDBC monitoring are described in the User guide.

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...
<jee:jndi-lookup id="dataSource" jndi-name="jdbc/myAppDS"/>
 
<bean id="entityManagerFactory"
	class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
	<property name="dataSource" ref="dataSource" />
...

Business facades (Spring)

If the application to monitor contains some objects initialized by Spring, EJB or Guice their methods execution can also be added to statistics. As described in the User guide for monitoring Spring Business facades there are couple of options and for example with JdkRegexpMethodPointcut in applicationContext-web.xml you can catch objects with regular expression like "all that have Service in their names".

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...
<bean id="facadeMonitoringAdvisor" class="net.bull.javamelody.MonitoringSpringAdvisor">
	<property name="pointcut">
		<bean class="org.springframework.aop.support.JdkRegexpMethodPointcut">
			<property name="pattern" value=".*Service.*" />
		</bean>
	</property>
</bean>
...

EHCache statistics

If you want to see also EHCache statistics add statistics="true" to ehcache.xml config file.

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<ehcache xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="http://ehcache.org/ehcache.xsd">
    <defaultCache eternal="true" maxElementsInMemory="100" overflowToDisk="false" statistics="true" />
    <cache name="fooCache" maxElementsInMemory="1000" eternal="false" overflowToDisk="false" />
    <cache name="barCache" maxElementsInMemory="1000" eternal="false" overflowToDisk="false" />
</ehcache>

Database information and statistics

JavaMelody already shows datasource and SQL information but it's also possible to display information and statistics on the database like the longest requests in cumulative time with display of the cpu time and of the elementary cost. For showing that information the user in the database used by the monitored application must have the necessary rights to read those information and statistics.

In Oracle database the request practically means select * from v$session and you can grant access as 'system' user with GRANT SELECT any dictionary TO myapplicationuser. Strangely granting just the select for v$session (GRANT SELECT ON sys.v_$session TO myapplicationuser;) wasn't enough.

Reports

There is also a possibility to get weekly, daily or monthly report in pdf format sent by email to one or several people. It needs iText library for webapp and Java's JavaMail and Activation libraries in your server for the mail session.

With WebLogic you add some email parameters in webapp's web.xml (above) and configure a Mail Session in WebLogic AdminServer: Services > Mail Sessions with JNDI Name and JavaMail properties. The report provides the same information you can find in monitoring web page with high and detailed level information.

Statistics' storage

Javamelody data is stored in files on disk and there are 2 types of files: *.rrd files for values in graphics in RRD format (using jrobin library) and *.ser.gz for values in statistics.

The performance statistics are stored to temp/javamelody directory by default which means /tmp/javamelody in Linux and in Windows when running webapp in Eclipse something like Users/developer/AppData/Local/Temp/javamelody. If you want to reset the counters just delete all the files. The location can be changed with storage-directory parameter and if the name of the directory starts with '/', it is considered as an absolute path, otherwise it is considered as relative to the temporary directory.

There is also option to use centralized collect server to store statistics and for monitoring of several applications.

Viewing performance monitoring

After you have set up your webapp to have the monitoring you can see statistics at URL like http:////monitoring depending your configuration.

Some example JavaMelody statistics from development:

Overhead

Monitoring and filtering doesn't come without costs and there has been discussions on JavaMelody wiki about the overhead the monitoring does. It is said that the overhead is so low that it can be enabled continuously in Quality Assuarance environment and if no problem arises in QA, also continuously in production environment. And with little overhead you will be able to know what needs optimizing in the QA or production servers so that the overhead of JavaMelody will practically be negative.

The discussion contained some notes:

  • Architecture of JavaMelody is lightweight so it has a lower overhead as compared it to other available solutions
  • It is only statistics and not events so the overhead of memory is quite minimal.
  • It does monitoring not profiling: there is no instrumentation of classes and instead "interceptors" for http, jdbc, spring or ejb3.
  • No database and no recording of each events even in a file or over the wire: only statistics of requests are kept. The overhead of cpu is minimal with no I/O on the wire and minimal I/O on disk (just to take a backup of statistics at a regular interval). The overhead of some other good monitoring solutions is in the recording of each event in a database or in a master server.
  • You have the choice to use centralized collect server which unloads the memory, the backup storage and the generation of reports to another server while adding I/O on the wire for sending deltas of the statistics.

Summary

"If you can not measure it, you can not improve it." It doesn't matter how you do it but if you want to use real user data and environment just do it non-intrusively with performance monitoring tools like Javamelody.

Eclipse and Maven Console

Eclipse 3.7 Indigo has integrated Maven m2e plugin but is missing some expected functionality which was previously present in Sonatype releases by default. If you want your Maven Console to show something you must also install the optional "m2e - slf4j over logback logging" plugin.

When installing the m2e plugin there is an optional feature "m2e - slf4j over logback logging" which is needed for the Maven Console to work. Without it the plugin produces no output to Eclipse's Maven Console view so that it is impossible to track plugin's activity (background maven builds, source and javadoc downloads, etc).

There is a bug filed about it but it is resolved with comment "As a tool, m2e is not in the position to impose any specific slf4j logging backend on the host Eclipse installation." That seems kinda strange as without the optional component the plugin is missing useful parts.

Just "Install new sofware > Indigo > Collaboration > "m2e - slf4j over logback logging (Optional)" and your Maven Console is back in business.