Virtualisation Howtos

Here I wrote down how I installed virtual Linux servers with UML and XEN. Hopefully this will help you get the best out of your Linux server hosting.

 

So far I have four HOWTOs:

I moved the commands for creating and deleting virtual servers into scripts, so that additional virtual servers can be installed easily.

There is also a script for backing up a virtual server while it ist running.

LVM snapshotting is used for backups without disturbing the servers. Unfortunately, this is not stable yet in kernel 2.6.

 

 
 
Apache Tomcat/5.5 - Error report

HTTP Status 500 -

type Exception report

message

description The server encountered an internal error () that prevented it from fulfilling this request.

exception 

org.apache.jasper.JasperException: Unable to compile class for JSP: 

An error occurred at line: 16 in the jsp file: /start.jsp
ESAPI.Encoder cannot be resolved to a type
13:   <%=mess.getMessage(Messages.START_HEADLINE)%>
14:   <br/>
15:   <form method="post" action="<%=postURL%>"  enctype="multipart/form-data">
16: 	<textarea name="<%=keyFile%>" rows="10" cols="80"><%=ESAPI.Encoder.encodeForHTML(xml, false)%></textarea>
17: 	<input type="hidden" name="<%=keyFilename%>" value="xml"/>
18: 	<%=embeddedParam%>
19: 	<br/>


Stacktrace:
	org.apache.jasper.compiler.DefaultErrorHandler.javacError(DefaultErrorHandler.java:93)
	org.apache.jasper.compiler.ErrorDispatcher.javacError(ErrorDispatcher.java:330)
	org.apache.jasper.compiler.JDTCompiler.generateClass(JDTCompiler.java:435)
	org.apache.jasper.compiler.Compiler.compile(Compiler.java:298)
	org.apache.jasper.compiler.Compiler.compile(Compiler.java:277)
	org.apache.jasper.compiler.Compiler.compile(Compiler.java:265)
	org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:564)
	org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:302)
	org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:329)
	org.apache.jasper.servlet.JspServlet.service(JspServlet.java:265)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
	sun.reflect.GeneratedMethodAccessor48.invoke(Unknown Source)
	sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
	java.lang.reflect.Method.invoke(Method.java:597)
	org.apache.catalina.security.SecurityUtil$1.run(SecurityUtil.java:244)
	java.security.AccessController.doPrivileged(Native Method)
	javax.security.auth.Subject.doAsPrivileged(Subject.java:517)
	org.apache.catalina.security.SecurityUtil.execute(SecurityUtil.java:276)
	org.apache.catalina.security.SecurityUtil.doAsPrivilege(SecurityUtil.java:162)

note The full stack trace of the root cause is available in the Apache Tomcat/5.5 logs.

Apache Tomcat/5.5