//*******************The Log class
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.uitl.Date;
import java.text.DateFormat;

public class Log{
   private static final String filePath = PropertyReader.getResource("Log_File_Path");//Supposing we have define in the last ProperyReader class and the file
  
   public static final String EXCEPTION                  =   "Exception";
   public static final String CREATE_STAFF           =   "Create Staff";
   public static final String EDIT_STAFF                 =   "Edit Staff";
   public static final String DELETE_STAFF            =   "Delete Staff";
   public static final String RECORD_HAS_EXIST  =   "Record Has Exist";

   public static void log(String msg_type, Exception e){
      StringBuffer errMsg = new StringBuffer(e.toString);
     
      for(int i=0;i<e.getStackTrace().length;i++){
         errMsg.append("\n\t at");
         errMsg.append(e.getStackTrace()[i].toString);
      }
      log(msg_type,errMsg.toString());
      OptionPanel.showErrMsg("Sorry,System may have an error \n System will exit");
      System.exit(-1);
   }

  public static void log(String msg.type,Staff staff){
     String msg = null;
     if(msg_type == CREATE_STAFF){
         msg = staff.toString() + "has benn created";
     }else if(msg_type == EDIT_STAFF){
         msg = staff.toString() + "has been Changed";
     }else if(msg_type == DELETE_STAFF){
         msg = staff.toString() + "has been Deleted";
     }else if(msg_type == RECORD_HAS_EXIST){
         msg = staff.toString() + "has exist in the database";
     }
     log(msg_type,msg);
  }

  private static void log(String msg_type,String msg){
      BufferedWriter out = null;
      DateFormat df = DateFormat.getDateInstance(DateFormat.MEDIUM);
     
      try{
        out = new BufferedWriter(new FileWriter(getLogFilePath(),true));//如果為 true，則將字節(jié)寫(xiě)入文件末尾處，而不是寫(xiě)入文件開(kāi)始處
        out.write("["+df.format(new Date()) + "] <" + msg_type + "> :" + msg);
        out.newline();
        out.newline();
      }catch(IOException e){
          e.printStackTrace();
      }finally{
         try{
           if(out!=null){
              out.close();
           }
         }catch(IOException e){
            e.printStackTrace();
         }
      }
  }

  private static String getLogFilePath(){
     File logDir = new File(filePath);
     if(!logDir.exists()){
       logDir.mkdir();
     }
    
     int i = 1;
     String fileName = filePath + "log_";
     File file = new File(fileName + i + ".txt");
   
     while(file.exists() && file.length() > 30000L) {
         i++;
         file = new File(fileName + i + ".txt");
     }
   
      return fileName + i + ".txt"
  }
}

//*****************************The OptionPanel Dialog Class for the Log Class
import javax.swing.JOptionPane;

public class OptionPanel {
   private static final String appTitle = PropertyReader.getResource("App_Title");//suposing the file has been established and the property app-title stands for the name of application
   private static final MainFrame frame = MainFrame.getMainFrame();

   public static void showWarningMsg(String msg){
      JOptionPane.showMessageDialog(frame,msg,appTitle,JOptionPane.WARNING_MESSAGE);
   }
   public static void showErrMsg(String msg){
       JOptionPane.showMessageDialog(frame,msg,appTitle,JOptionPane.Error_MESSAGE);
   }
   public static int showConfirmMsg(String msg){
        return JOptionPane.showConfirmDialog(frame,msg,appTitle,JOptionPane.YES_NO_OPTON,JOptionPane.QUESTION_MESSAGE);
   }
}

In a project, we can write a class to read the properties.As following,

import java.io.InputStream;
import java.io.IOException;
import java.util.Properties;

public class PropertyReader{
   private static Properties property = null;
  
   static{
      InputSteam stream = null;
      try{
        stream=PropertyReader.class.getResourceAsStream("/resource/properties.properties");
        property = new Properties();
        property.load(stream);
      }catch(IOException e){
          e.printStackTrace();
      }finally{
          if(stream != null){
             try{
                stream.close();
             }catch(IOException e){
                e.printStackTrace();
             }           
          }
      }
   }
   public static String getResource(String key){
     if(property == null){
       return null;// init error;
     }
     
     return property.getProperty(key);
   }
}

Most developers have heard of, and possibly used, scripting languages such as Ruby, JavaScript, and Python. These dynamic languages are enjoying a resurgence in popularity, largely because of their flexibility and simplicity, and the productivity gains they promise.

Java 6 comes with built-in support for scripting languages. You can embed scripts in various scripting languages into your Java applications, passing parameters, evaluating expressions, and retrieving results. And you can do it all pretty seamlessly.

First of all, you obtain a new ScriptEngine object from a ScriptEngineManager, as shown here:

ScriptEngineManager manager = new ScriptEngineManager();


ScriptEngine engine = manager.getEngineByName("js");

Each scripting language has its own unique identifier. The "js" here means you're dealing with JavaScript.

Now you can start having some fun. Interacting with a script is easy and intuitive. You can assign scripting variables using the put() method and evaluate the script using the eval() method,. which returns the most recently evaluated expression processed by the script. And that pretty much covers the essentials. Here's an example that puts it all together:

engine.put("cost", 1000);
String decision = (String) engine.eval(
"if ( cost >= 100){ " +
"decision = 'Ask the boss'; " +
"} else {" +
"decision = 'Buy it'; " +
"}");
assert ("Ask the boss".equals(decision));

You can do more than just pass variables to your scripts— you can also invoke Java classes from within your scripts. Using the importPackage() function enables you to import Java packages, as shown here:

				

        engine.eval("importPackage(java.util); " +
                    "today = new Date(); " +
                    "print('Today is ' + today);");

Another cool feature is the Invocable interface, which lets you invoke a function by name within a script. This lets you write libraries in scripting languages, which you can use by calling key functions from your Java application. You just pass the name of the function you want to call, an array of Objects for the parameters, and you're done! Here's an example:

				

        engine.eval("function calculateInsurancePremium(age) {...}");
        Invocable invocable = (Invocable) engine;
        Object result  = invocable.invokeFunction("calculateInsurancePremium",
                                     new Object[] {37});

You actually can do a fair bit more than what I've shown here. For example, you can pass a Reader object to the eval() method, which makes it easy to store scripts in external files, or bind several Java objects to JavaScript variables using a Map-like Binding object. You can also compile some scripting languages to speed up processing. But you probably get the idea that the integration with Java is smooth and well thought-out.

前幾天好不容易下到了JDK6mustang，今天恰好有時(shí)間升級(jí)了一下Netbeans默認(rèn)的JDK版本。這里簡(jiǎn)單的說(shuō)明一下升級(jí)的方法。如果我 們不修改Netbeans的屬性，需要在JavaPlatform manager中加入另一版本的類(lèi)庫(kù)。新建工程后如果要修改類(lèi)庫(kù)，還需要修改項(xiàng)目的類(lèi)庫(kù)屬性，現(xiàn)在通過(guò)修改默認(rèn)的JDK類(lèi)庫(kù)，便可方便很多，更不需要重新 安裝NB。

我的NB裝在D盤(pán)中，可以在該路徑找到文件D:\Netbeans-5.5\etc\Netbeans.conf，我們將原有的默認(rèn)類(lèi)庫(kù)netbeans_jdkhome="D:\Java\jdk1.5.0_07"修改為 netbeans_jdkhome="D:\Java\jdk1.6.0"便輕松的完成了升級(jí)，當(dāng)然在tools-〉JavaPlatform manager〉中當(dāng)然也可以將我們慣用的D:\Java\jdk1.5.0_07加入為可選用類(lèi)庫(kù)。

第三步，輸入啟動(dòng)類(lèi)。輸入帶有 main 方法的類(lèi)名

今天在sun的網(wǎng)站上轉(zhuǎn)了一圈，等了好幾天的Visual Web Pack終于出來(lái)了.

先介紹一下

Creates a new Visual Web Pack project containing an empty web application. This project enables you to use Visual Web Pack features like the Visual Designer to drag and drop JSF components, visual and dialog box support for binding components to data providers, and generation of Java code and Web XML files. The project uses the IDE-generated build script to build, run, and debug your project.

創(chuàng)建一個(gè)可視化頁(yè)面工程包 包含一個(gè)空白頁(yè)面應(yīng)用程序.這個(gè)工程能讓你使用可視化開(kāi)發(fā)包的各種屬性，諸如用可視化設(shè)計(jì)工具拖放JSF(java server face)組件,可視化的對(duì)話框支持將組件數(shù)據(jù)源（或者數(shù)據(jù)提供者）綁定在一起，并且生成java代碼和xml頁(yè)面文件。這一工程由集成開(kāi)發(fā)環(huán)境（IDE）生成的構(gòu)建腳本來(lái)構(gòu)造，執(zhí)行和調(diào)試你的項(xiàng)目。

(翻譯的不好請(qǐng)見(jiàn)諒)

還支持ajax，呵~~呵~~~。

最終裝好的效果圖:

全面支持拖放，呵呵，上次裝了一個(gè)java studio creator結(jié)果運(yùn)行死慢死慢的，這一次把這一功能轉(zhuǎn)移到了netbeans挺好用，速度也不錯(cuò)，我這臺(tái)筆記本都能挺過(guò)來(lái)，臺(tái)式機(jī)估計(jì)沒(méi)什么問(wèn)題。

安裝時(shí)要注意的地方:

1.netbeans必須為5.5正式版本，beta版本的檢測(cè)不到。點(diǎn)擊進(jìn)入netbeans首頁(yè)

2.下載JDK 5_60或者以后的版本我用的是JDK 5_09版本，安裝的時(shí)候最好不要把原來(lái)的卸載，有時(shí)候老程序不認(rèn)新的JDK。點(diǎn)擊進(jìn)入JDK下載頁(yè)面

點(diǎn)擊這里進(jìn)入Visual Web Pack 的下載頁(yè)面。

October 20, 2006 - Anyone who believes college students today are lacking in initiative, creativity, or work ethic should take a close look at the recent accomplishments of a team of students at the Ecole de Technologie Superieure (ETS) in Montreal, Quebec. Over the past three years, this team of 12 has been heads-down working on the mechanical design, electrical system, and Java™ control and navigation software for an AUV—a submarine—and preparing it for the International Autonomous Underwater Competition sponsored by the Association for Unmanned Vehicles Systems International (AUVSI) and the Office of Naval Research (ONR) in San Diego, California.

SONIA Team Click here for more images

For no college credits, no pay, and no guarantee of success, the ETS team designed and built an AUV that could meet the complex and demanding mission requirements of the competition. Detailed in an 18-page document, these requirements included the ability to autonomously pass through a gate, detect a flashing light, find and connect with a docking station, locate a pipe and drop material into a bin—all underwater and with no communication with the team.

The submarine is called SONIA, which stands for Système d’Opérations Nautiques Intelligent et Autonome, and is just over one meter long, with a dry weight of 20 kg and a unique box-shaped design. It is equipped with sensors and two color video cameras. Navigation data input is provided by a compass and two gyroscopes as well as active and passive sonar arrays.

SONIA outperformed all but two of the 21 entries in the student competition, securing a place for ETS on the podium for a fourth year in a row. With an overall budget of just $15,000 U.S. (provided by ETS and a variety of corporate sponsors), the ETS team scored higher than teams with six-figure budgets. The competition was won by the University of Florida, but the ETS team came out ahead of renowned engineering schools such as MIT, Georgia Tech, and Virginia Tech.

Innovative Design, Expert Software Engineering

Two of the characteristics that set SONIA apart from competitors were its innovative box-shaped design and the sophistication of its core software systems.

SONIA underwater Click here for more images

The ETS team’s expertise with Java software proved a decisive advantage. Martin Morissette, software team leader of the SONIA team, is currently entering his third year in software engineering, and recently completed a six-month internship at Sun Labs, where he worked on the “Squawk VM,” a small J2ME™ virtual machine (VM) written almost entirely in Java. The Squawk VM provides the ability to run wireless transducer applications directly on the CPU without any underlying OS, saving overhead and improving performance.

“I learned a great deal during my time with Sun Labs that was extremely useful in the development of the navigation software for SONIA,” said Morissette. “The fact is, Java is an excellent programming language for robotics. All schools teach Java, so everyone on the software team knows how to use it. It’s object-oriented; it’s portable so it runs on Macs, PCs, Linux, whatever; it’s very efficient so we don’t have to worry about memory management; and there are lots of APIs available. And if you know how to write your applications properly, it can be very fast.”

The ETS team used Java for mission control and SONIA’s control systems, Java Management Extensions (JMX) for management, and a Java 3-D Simulator to simulate a broad range of mission scenarios. The team is now investigating the possibilities of Real-time Java, introduced at this year’s JavaOne Conference, for AUV and other robotics applications.

Consensus Building and Peer Review

According to Mr. Mercier, teamwork was every bit as important as technology in the ETS team’s success. “I can’t stress strongly enough that our ability to work together was the key to our success in the competition,” he said. “This is not about 12 individuals working on separate tasks by themselves. Every step of the way, we worked as a team and built consensus, so in the end everyone learned more. And that’s what this is really all about.”

For example, each software change was subject to peer review. All team members would receive an e-mail containing the previous version of the software, the new version incorporating a proposed change, and the rationale behind the change. Far from slowing the process down, the peer review concept got more team members more actively engaged, and ultimately resulted in far higher quality, according to Mr. Mercier. These peer reviews also ease the integration of new team members. Being a volunteer based project, volunteers come and go on a regular basis.

At the same time, the team shared tips and tricks with peers at other educational institutions. “This is more of a friendly rivalry than a dog-eat-dog competition,” said Tennessee Carmel-Veilleux, electrical team leader of the SONIA team. “We like to exchange information with some of the other teams, keep in touch with them. Who knows—we may all be working together some day.”

In recognition of the team’s willingness to work with other teams, and for achievements at the Unmanned Underwater Vehicle Competition, Felix Pageau, team captain, won the Andy Estabrook Award for "initiative and vision in the unmanned underwater systems.” Given for the first time to a student, the award was presented by the Lindbergh Chapter, San Diego, CA, of the AUVSI. Andy Estabrook was a pioneer in unmanned robotics and this award was created to honor his accomplishments in the advance of unmanned systems technology.

What’s next for the ETS team? The team itself is growing rapidly, thanks in part to the success at this year’s competition. The team leaders now find themselves in management roles as the team’s ranks have swollen to 34. “We’re going to compete again next year, and we’re going to focus on making our software more stable, more reliable, and faster,” said Mr. Morissette. In the mean time, the team leaders will be presenting their work at a variety of conferences worldwide—from Florida and Washington D.C. to Cologne, Germany.

And when will they get around to more traditional college activities such as frat parties and beer runs? “Probably never,” said Mr. Mercier. “We’re geeks. We’re doing what we love.”

For more information:

• SONIA website: http://sonia.etsmtl.ca
• Project Squawk (Java implementation of Project SunSPOT):http://research.sun.com/projects/squawk/
• Real-Time Specification for Java (RTSJ): http://www.rtsj.org
• Association for Unmanned Vehicle Systems International (AUVSI) http://www.auvsi.org/
• AUVSI Lindbergh Chapter: http://www.sd-auvsi.org/index.html

(2006年5月25日訊)　Sun Microsystems公司發(fā)布了一個(gè)具有革命性的新的文檔系統(tǒng)Solaris ZFS 1.0，它提供了多項(xiàng)突破性的功能，包括公共管理任務(wù)的自動(dòng)化、保護(hù)數(shù)據(jù)免受非法行為的侵害，以及提供實(shí)際上無(wú)限的縮放能力。Solaris ZFS 1.0將作為我們這個(gè)星球上最先進(jìn)的操作系統(tǒng)Solaris 10 OS的下一個(gè)商業(yè)版本的一個(gè)組成部分在今年6月份對(duì)外正式提供。此外，Solaris 10 OS的最新版本Solaris 10 6/06將先進(jìn)的前攝性自愈技術(shù)和聯(lián)網(wǎng)技術(shù)，與對(duì)PostgreSQL開(kāi)源數(shù)據(jù)庫(kù)的全面支持結(jié)合起來(lái)，進(jìn)一步強(qiáng)化了Solaris 10 OS作為宿主高性能的關(guān)鍵數(shù)據(jù)庫(kù)解決方案的首選平臺(tái)的地位。

作為世界上最先進(jìn)的文檔系統(tǒng)，Solaris ZFS可以自動(dòng)檢測(cè)和修改細(xì)小的數(shù)據(jù)錯(cuò)誤或遭遇意外侵害的數(shù)據(jù)，以提供信息的完整性。Solaris ZFS還因?yàn)椴恍枰碜诠芾砥鞫蟠蠛?jiǎn)化了數(shù)據(jù)的管理，而卷宗管理器是今天數(shù)據(jù)管理事務(wù)中最耗時(shí)、最費(fèi)錢(qián)的部分。例如，今天，一項(xiàng)典型的系統(tǒng)管理任務(wù)可能 需要40多分鐘來(lái)完成，但是采用Solaris ZFS，僅僅需要幾秒鐘的時(shí)間，且沒(méi)有系統(tǒng)宕機(jī)的危險(xiǎn)，從而大大降低了數(shù)據(jù)管理的成本費(fèi)用。此外，Solaris ZFS還是世界上第一個(gè)128位的文檔系統(tǒng)，這使系統(tǒng)具有了實(shí)際上無(wú)限的數(shù)據(jù)容量。Solaris ZFS提供的先進(jìn)的縮放能力和管理能力，使它成為許許多多傳統(tǒng)UNIX?文檔系統(tǒng)的理想替代品。

Solaris是宿主高性能數(shù)據(jù)庫(kù)的杰出平臺(tái)。最近，Oracle指名Solaris 10 OS作為其開(kāi)源64位開(kāi)發(fā)和部署環(huán)境的理想平臺(tái)。現(xiàn)在，Sun還將開(kāi)源PostgreSQL數(shù)據(jù)庫(kù)集成在Solaris 10 OS的最新版本內(nèi)，對(duì)PostgreSQL數(shù)據(jù)庫(kù)提供全面支持。Sun與PostgreSQL社團(tuán)開(kāi)展合作，讓他們采用Solaris 10 OS提供的各種先進(jìn)技術(shù)，如前攝性自愈技術(shù)、Solaris分區(qū)特性和Solaris動(dòng)態(tài)跟蹤能力(DTrace)等。

“面對(duì)不斷增長(zhǎng)的依順性要求，今天的數(shù)據(jù)量每9～12個(gè)月就要翻番，但今天的文檔系統(tǒng)還植根在上世紀(jì)70年代的技術(shù)之中，”Sun公司主管系統(tǒng)軟件部的 副總裁Tom Goguen說(shuō)，“Solaris ZFS從設(shè)計(jì)之初就是要迎接今天數(shù)據(jù)管理的挑戰(zhàn)，它的預(yù)期壽命是20～30年。這一128位的文檔系統(tǒng)所能存儲(chǔ)的自愈數(shù)據(jù)是今天已有文檔系統(tǒng)的160億 倍，同時(shí)還大大簡(jiǎn)化了卷宗的管理。Solaris ZFS將是今年內(nèi)發(fā)布的最重要的創(chuàng)新技術(shù)之一。”

Solaris 10是我們這個(gè)星球上最先進(jìn)的操作系統(tǒng)，它可在650多款SPARC和x64/x86平臺(tái)上運(yùn)行，獲得來(lái)自獨(dú)立軟件廠商的2,200多種應(yīng)用程序的支持。 其無(wú)與倫比的功能性和硬件平臺(tái)的支持，加上它所提供的行業(yè)唯一的應(yīng)用兼容性保證，加快了Solaris 10 OS在全球的應(yīng)用步伐，目前Solaris 10 OS的注冊(cè)許可數(shù)已超過(guò)450萬(wàn)。

具有革命性的新的文檔系統(tǒng)技術(shù)

Solaris ZFS 1.0具有任何其他商用文檔系統(tǒng)技術(shù)所無(wú)法匹敵的優(yōu)異性能。客戶可以從Solaris ZFS技術(shù)中享用到先進(jìn)的數(shù)據(jù)完整性技術(shù)、使用和管理的簡(jiǎn)易性、難以置信的高性能，以及實(shí)際上無(wú)限的縮放能力。

• 端到端的數(shù)據(jù)完整性―― 基于校驗(yàn)和與事務(wù)性寫(xiě)入復(fù)制(copy-on-write)機(jī)制的突破性的結(jié)合，Solaris ZFS可提供滿足CIO和系統(tǒng)管理員要求的數(shù)據(jù)準(zhǔn)確性。Solaris ZFS擁有先進(jìn)的錯(cuò)誤檢測(cè)機(jī)制，能識(shí)別被損壞的數(shù)據(jù)，并將之在運(yùn)行中修改過(guò)來(lái)。例如，鏡像的一側(cè)被意外地重寫(xiě)，ZFS可以對(duì)之檢測(cè)、修補(bǔ)和恢復(fù)，且完全不 干擾服務(wù)的進(jìn)行。
• 簡(jiǎn)化的管理――Solaris ZFS提供了一種基于共享的架構(gòu)模式，使所有的共享數(shù)據(jù)和功能納入虛擬內(nèi)存管理。Solaris ZFS文檔系統(tǒng)可以自動(dòng)地增長(zhǎng)或收縮，而無(wú)需占據(jù)額外存儲(chǔ)空間的卷宗管理器。Solaris ZFS還提供了在任何時(shí)間點(diǎn)上對(duì)文檔系統(tǒng)進(jìn)行瞬間快照的能力，這就大大節(jié)約了一般系統(tǒng)管理員手工恢復(fù)文檔所花費(fèi)的時(shí)間和資源。
• 性能的巨大提升――Solaris ZFS的架構(gòu)設(shè)計(jì)有助于提高速度。寫(xiě)入復(fù)制的設(shè)計(jì)可將隨意寫(xiě)入轉(zhuǎn)變?yōu)榭焖龠B續(xù)寫(xiě)入。其輸入/輸出(I/O)帶寬在有數(shù)據(jù)存儲(chǔ)時(shí)可自動(dòng)加大。無(wú)論工作量如 何，多種字區(qū)尺寸會(huì)自動(dòng)做出最佳配合。智能化的預(yù)取感式讀取可加快運(yùn)行速度。而且，它的高級(jí)的、可擴(kuò)展的I/O子系統(tǒng)設(shè)計(jì)采用了記分板式的流水線操作和依 賴(lài)性時(shí)序安排，同樣提供了極大的性能提升。
• 無(wú)限的數(shù)據(jù)容量――Solaris ZFS是世界上第一個(gè)128位文檔系統(tǒng)，具有實(shí)際上無(wú)限的數(shù)據(jù)容量。
  

Sun公司簡(jiǎn)介

一個(gè)獨(dú)具特色的理念――“網(wǎng)絡(luò)就是計(jì)算機(jī)”，指引著Sun各項(xiàng)技術(shù)的發(fā)展，為全球各個(gè)重要的市場(chǎng)增添活力。Sun共享創(chuàng)新和創(chuàng)建社團(tuán)的思想體系處于新 一代網(wǎng)絡(luò)計(jì)算－參與時(shí)代－的最前沿。Sun的足跡遍及全球100多個(gè)國(guó)家和地區(qū)，其互聯(lián)網(wǎng)的網(wǎng)址為http://www.sun.com。Sun公司的中 文網(wǎng)址為http://www.sun.com.cn。

ZFS是第一個(gè)128位的文件系統(tǒng)，同時(shí)ZFS又被Sun Microsystems稱(chēng)作史上最后一個(gè)文件系統(tǒng)。因?yàn)檫@個(gè)文件系統(tǒng)含有多項(xiàng)創(chuàng)新技術(shù)，不僅成功地解決現(xiàn)有文件系統(tǒng)的問(wèn)題和陋習(xí)，而且前瞻性地考量了未 來(lái)對(duì)存儲(chǔ)空間的需求，單個(gè)文件系統(tǒng)可以達(dá)到256 quadrillion（264） Zettabytes（221）。 ZFS不僅符合POSIX文件系統(tǒng)的標(biāo)準(zhǔn)，而且提供了許多高級(jí)功能比如：Quota(配額)，Reservation(預(yù)留), Compression(壓縮)， Snapshot(快照)，Clone（克隆）等。如果你還在堅(jiān)持使用現(xiàn)有32位或者64位的文件系統(tǒng)，如果你還在“痛并不快樂(lè)著”地用著各式各樣的 Volume Manager，那就很值得看看這里列出的使用ZFS的十條理由。

1. 再也不需要fsck, scandisk

不管你是在用Linux，UNIX還是Windows，相信大家都有過(guò)類(lèi)似的體會(huì)：當(dāng)系統(tǒng)意外斷電或者非法關(guān)機(jī)，系統(tǒng)重起后發(fā)現(xiàn)文件系統(tǒng)有 inconsistent的問(wèn)題，這時(shí) 候就需要fsck或者scandisk 來(lái)修復(fù)，這段時(shí)間是非常耗時(shí)而且最后不一定能夠修復(fù)成功。更糟糕的是，如果這是一臺(tái)服務(wù)器需要做fsck的時(shí)候，只能offline（下線），而且現(xiàn)有應(yīng) 用往往都是大硬盤(pán)，相應(yīng)fsck修 復(fù)時(shí)間也很長(zhǎng)，這對(duì)許多使用該服務(wù)器的用戶來(lái)說(shuō)幾乎不能忍受的。而使用ZFS后大家可以徹底拋棄fsck這種工具，因?yàn)閆FS是一個(gè)基于COW（Copy on Write）機(jī)制的文件系統(tǒng)。COW是不會(huì)對(duì)硬盤(pán)上現(xiàn)有的文件進(jìn)行重寫(xiě)，保證所有硬盤(pán)上的文件都是有效的。所以不會(huì)有這種inconsistent的概 念，自然就不需要這種工具了。

2. 管理簡(jiǎn)單

　　ZFS作為一個(gè)全新的文件系統(tǒng)，全面拋棄傳統(tǒng)File System + Volume Manager + Storage的架構(gòu)，所有的存儲(chǔ)設(shè)備是通過(guò)ZFS Pool進(jìn)行管理，只要把各種存儲(chǔ)設(shè)備加 入同一個(gè)ZFS Pool，大家就可以輕松的在這個(gè)ZFS Pool管理配置文件系統(tǒng)。大家再也不用牢記各種專(zhuān)業(yè)概念，各種命令newfs, metinit及各種Volume Manager的用法。在ZFS中我們只需要兩個(gè)命令，zpool(針 對(duì)ZFS Pool管理)和zfs(針對(duì)ZFS文件系統(tǒng)的管理)，就可以輕松管理128位的文件系統(tǒng)。舉個(gè)例子，我們經(jīng)常會(huì)遇到系統(tǒng)數(shù)據(jù)增長(zhǎng)過(guò) 快，現(xiàn)有存儲(chǔ)容量不夠，需要添加硬盤(pán)，如果依照傳統(tǒng)的Volume Manager管理方式，那我 們需要預(yù)先要考慮很多現(xiàn)有因素，還要預(yù)先根據(jù)應(yīng)用計(jì)算出需要配置的各種參數(shù)。在ZFS情況下，我們的系統(tǒng)管理員可以徹底解放，再也不需要這種人為的復(fù)雜 考慮和計(jì)算，我們可以把這些交給ZFS，因?yàn)閆FS Pool會(huì)自動(dòng)調(diào)節(jié)，動(dòng)態(tài)適應(yīng)需求。我們只需一個(gè)簡(jiǎn)單的命令為 這個(gè)ZFS Pool加入新的硬盤(pán)就可以了：

zpool add zfs_pool mirror c4t0d0 c5t0d0

　　基于這個(gè)動(dòng)態(tài)調(diào)節(jié)的ZFS Pool之上的所有的文件系統(tǒng)就可以立即使用到這個(gè)新的硬盤(pán)，并且會(huì)自動(dòng)的選擇最優(yōu)化的參數(shù)。

　　而且ZFS同時(shí)也提供圖形化的管理界面，下面是一個(gè)ZFS圖形化管理的一個(gè)截屏：

[attachment=2119]

3. 沒(méi)有任何容量限制

ZFS（Zettabyte File System）文件系統(tǒng)就如其名字所預(yù)示，可以提供真正的海量存儲(chǔ)，在現(xiàn)實(shí)中幾乎不可能遇到容量問(wèn)題。在現(xiàn)有的64位kernel（內(nèi) 核）下，它可以容納達(dá)到16 Exabytes(264)大小的單個(gè)文件，可以使用264個(gè)存儲(chǔ)設(shè)備，可以創(chuàng)建264個(gè)文件系統(tǒng)。

4. 完全保證 數(shù)據(jù) 的正確和完整

由于ZFS所有的數(shù)據(jù)操作都是基 于Transaction（事務(wù)），一組相應(yīng)的操作會(huì)被ZFS解 析為一個(gè)事務(wù)操作，事務(wù)的操作就代表著一組操作要么一起失敗，要么一起成功。而且如前所說(shuō)，ZFS對(duì) 所有的操作是基于COW（Copy on Write）， 從而保證設(shè)備上的數(shù) 據(jù)始終都是有效的，再也不會(huì)因?yàn)橄到y(tǒng)崩潰或者意外掉電導(dǎo)致數(shù)據(jù)文件的inconsistent。

還有一種潛在威脅 數(shù)據(jù)的可能是來(lái)自于硬件設(shè)備的問(wèn)題，比如磁 盤(pán)，RAID卡的硬件問(wèn)題或者驅(qū)動(dòng)bug。現(xiàn)有文件系統(tǒng)通常遇到這個(gè)問(wèn)題，往往只是簡(jiǎn)單的把錯(cuò)誤數(shù)據(jù)直接交給上層應(yīng)用，通常我們把這個(gè)問(wèn)題稱(chēng)作 Silent Data Corruption。而在ZFS中，對(duì)所有數(shù)據(jù)不管是用戶數(shù)據(jù)還是文件系統(tǒng)自身的metadata數(shù) 據(jù)都進(jìn)行256位的Checksum（校 驗(yàn)），當(dāng)ZFS在提交數(shù)據(jù)時(shí)會(huì)進(jìn)行校驗(yàn)，徹底杜絕這種Silent Data Corruption情況。

5. 提供優(yōu)異 性能和擴(kuò)展性

　　和傳統(tǒng)File System + Volume Manager + Storage架構(gòu)不同，ZFS則是直接基于存儲(chǔ)設(shè)備提供所有的功能，因此有自己獨(dú)有的創(chuàng)新特性，性能自然非比尋常。

  * Dynamic Striping vs. Static Striping

由于ZFS是基于COW和一個(gè)全局動(dòng)態(tài)的ZFS Pool，任何一次寫(xiě) 操作，都是對(duì)一塊新數(shù)據(jù)塊（Block）的一次寫(xiě)操作。ZFS從ZFS Pool中動(dòng)態(tài)挑選出一個(gè)最優(yōu)的設(shè)備，并且以一個(gè)transaction（事 務(wù)）線性寫(xiě)入，充分有效地利用了現(xiàn)有設(shè)備的帶寬，我們把這個(gè)特性稱(chēng)為Dynamic Striping。而相對(duì)應(yīng)的Static Striping則是傳統(tǒng)文件系統(tǒng)所使用的方式，Static Striping需要管理員預(yù)先對(duì)這組Stripe進(jìn)行正確地計(jì)算人為 設(shè)置，而且如果加入新的設(shè)備則需要再次人為的計(jì)算和設(shè)置，更為嚴(yán)重的是如果人為計(jì)算錯(cuò)誤，則會(huì)直接影響系統(tǒng)的性能。而在使用Dynamic Striping這種特性之后，我們根本不需要人為介入，ZFS會(huì)自動(dòng)調(diào)整，智能的為你 提供最佳的設(shè)備，最快的操作方式。

  * 支持多種 大小的數(shù)據(jù)塊（Multiple Block Size）

　　ZFS支持多種大小的數(shù)據(jù)塊定義，從512字節(jié)到1M字節(jié)。和傳統(tǒng)文件系統(tǒng)往往都是固定大小數(shù)據(jù)塊不同，ZFS則是可以動(dòng)態(tài)的根據(jù)不同 大小的文件進(jìn)行計(jì)算，動(dòng)態(tài)的選擇最佳的數(shù)據(jù)塊。

因?yàn)椴煌笮?shù)據(jù) 塊，直接影響到實(shí)際使用硬盤(pán)容量和讀取速度。如果使用較小的數(shù)據(jù)塊，存儲(chǔ)文件所導(dǎo)致的碎片則較少，讀寫(xiě)小文件更快一些，但是會(huì)導(dǎo)致需要?jiǎng)?chuàng)建更多的 metadata，讀寫(xiě)大文件則會(huì)更費(fèi)時(shí)。如果使用較大的數(shù)據(jù)塊，使用的metadata較少，更利于讀寫(xiě)大文件，但是會(huì)導(dǎo)致更多的碎片。ZFS根據(jù)實(shí)際 調(diào)查現(xiàn)有文件使 用的情況，分析出一個(gè)選擇數(shù)據(jù)塊大小的算法，動(dòng)態(tài)的根據(jù)實(shí)際文件大小確定最佳的數(shù)據(jù)塊。所以ZFS是 非常智能的，在不需要系統(tǒng)管理員介入，就可以得到一個(gè)自我調(diào)優(yōu)的結(jié)果。當(dāng)然ZFS也支持用戶對(duì)單個(gè)文件或者整個(gè)文件系統(tǒng) 所使用的數(shù)據(jù)塊大小的自定義設(shè)置。

  * 智能預(yù)讀取（Intelligent Prefetch）

　　多數(shù)的操作系 統(tǒng)都 有這種將數(shù)據(jù)預(yù)先讀取的功能，而ZFS則是建立在文件系統(tǒng)上直接提供的一種更加智能的數(shù)據(jù)預(yù)讀取功能。它不僅可以智能地識(shí)別出多種讀取模式， 進(jìn) 行提前讀取數(shù)據(jù)，而且可以對(duì)每個(gè)讀取數(shù)據(jù)流進(jìn)行這種預(yù)讀取智能識(shí)別，這個(gè)對(duì)許多流媒體提供者來(lái)說(shuō)是件非常好的事情。

　　在擴(kuò)展性上，和現(xiàn)有文件系統(tǒng)多是基于一個(gè)受限的靜態(tài)模型不同，ZFS是采用ZFS Pool這個(gè)動(dòng)態(tài)概念，它的metadata也是動(dòng)態(tài)，并且讀寫(xiě)操作都是可并行的，并且具有優(yōu)先級(jí)概念，所以即使在大數(shù)據(jù)量，多設(shè)備的情況下仍可以保證性能的線性增長(zhǎng)。

6. 自我修復(fù)功能

  * ZFS Mirror 和 RAID-Z

傳統(tǒng)的硬盤(pán)Mirror及RAID 4，RAID 5陣列方式都會(huì)遇到前面提到過(guò)的問(wèn)題：Silent Data Corruption。如果發(fā)生了某塊硬盤(pán)物理問(wèn)題導(dǎo)致數(shù)據(jù)錯(cuò)誤，現(xiàn)有的Mirror，包括RAID 4，RAID 5陣列會(huì)默默地把這個(gè)錯(cuò)誤數(shù)據(jù)提交給上層應(yīng)用。如果這個(gè)錯(cuò)誤發(fā)生在Metadata中，則會(huì)直接導(dǎo)致系統(tǒng)的Panic。 而且還有一種更為嚴(yán)重的情況是：在RAID 4和RAID 5陣列中，如果系統(tǒng)正在計(jì)算Parity數(shù)值，并再次寫(xiě)入新數(shù)據(jù)和新Parity值的時(shí)候發(fā)生斷電，那么整個(gè)陣列的所有存儲(chǔ)的數(shù)據(jù)都毫無(wú)意義了。

在ZFS中則提出了相對(duì)應(yīng)的ZFS Mirror和RAID-Z方式，它在負(fù)責(zé)讀取數(shù)據(jù)的時(shí)候會(huì)自動(dòng)和256位校驗(yàn)碼進(jìn)行校驗(yàn)，會(huì)主動(dòng)發(fā)現(xiàn)這種Silent Data Corruption，然后通過(guò)相應(yīng)的Mirror硬 盤(pán)或者通過(guò)RAID-Z陣列中其他硬盤(pán)得到正確的數(shù)據(jù)返回給上層應(yīng)用，并且同時(shí)自動(dòng)修復(fù)原硬盤(pán)的Data Corruption 。

  * Fault Manager

在Solaris 10中，包含 一個(gè)ZFS診斷引擎和Solaris的 Fault Manager（這也是Solaris 10的 另一個(gè)新特性）交互，可以實(shí)時(shí)地診斷分析并且報(bào)告ZFS Pool和存儲(chǔ)設(shè)備的錯(cuò)誤，用戶可以通過(guò)Fault Manager及時(shí)得到一個(gè)非常友善的消息。這個(gè)診斷引擎雖然不會(huì)采取主動(dòng)的行為去修復(fù)或者解決 問(wèn)題，但是會(huì)在消息中提示系統(tǒng)管理員可采取的動(dòng)作。類(lèi)似下面一個(gè)ZFS報(bào)錯(cuò)消息，其中REC-ACTION就是建議采取的動(dòng)作：

SUNW-MSG-ID: ZFS-8000-D3, TYPE: Fault, VER: 1, SEVERITY: Major

EVENT-TIME: Fri Mar 10 11:09:06 MST 2006

PLATFORM: SUNW,Ultra-60, CSN: -, HOSTNAME: neo

SOURCE: zfs-diagnosis, REV: 1.0

EVENT-ID: b55ee13b-cd74-4dff-8aff-ad575c372ef8

DESC: A ZFS device failed. Refer to http://sun.com/msg/ZFS-8000-D3 for more information.

AUTO-RESPONSE: No automated response will occur.

IMPACT: Fault tolerance of the pool maybe compromised.

REC-ACTION: Run ’zpool status -x’ and replace the bad device.

7. 安全

　　在安全上，ZFS支持類(lèi)似NT風(fēng)格NFSv4版的ACL（讀取控制列表）。而且前面所提到的256位驗(yàn)證碼，用戶可選擇多種驗(yàn)證方式，包括SHA-256驗(yàn)證算法，從而在物理存儲(chǔ)單元級(jí)別上保證數(shù)據(jù)的安全性。

8. 超強(qiáng)功能

ZFS作為“最后一個(gè)文件系統(tǒng)”，涵蓋了基本的文件系統(tǒng)和Volume管理的功能，同時(shí) 一并提供許多企業(yè)級(jí)別的超強(qiáng)功能：Quota(配額)，Reservation(預(yù)留), Compression(壓 縮)， Snapshot(快照)，Clone（克隆）。并且速度非常快。有了這個(gè)文件系統(tǒng)，大家再也不需要任何Volume Manager了。

9. 兼容性

ZFS是一個(gè)完全兼容POSIX規(guī)范的文件系統(tǒng)，所以處于上層的應(yīng)用程序是完全不受影響。ZFS也提供一個(gè)Emulated Volume模塊，可以把任何一個(gè)ZFS文件系統(tǒng)作為普通的塊設(shè)備使用。同時(shí)ZFS也可以使用基于Volume Manager構(gòu)建的Volume作為存儲(chǔ)設(shè)備單 元。這樣在不需要修改應(yīng)用程序，不修改已有文件系統(tǒng)下，給了大家最大的自由度去獲得ZFS提供的各 種特性。

10. 開(kāi)源

　　ZFS是Sun Microsystems公 司作為OpenSolaris的一個(gè)開(kāi)源項(xiàng)目運(yùn)作并且完全免費(fèi)使用，點(diǎn)擊這里(http://www.opensolaris.org/os/community/zfs/source/) 可以直接瀏覽到ZFS的代碼。 這就代表著我們不僅同時(shí)可以享受商業(yè)公司的高質(zhì)量，也可以獲得開(kāi)源模式的優(yōu)點(diǎn)。

雖然目前只有Solaris支持該文件系統(tǒng)，但是這種開(kāi)源的模式必定會(huì)促進(jìn)更多基于ZFS的應(yīng)用。現(xiàn)在已經(jīng)有國(guó)外開(kāi)發(fā)者正在將ZFS移植到Linux和 Mac OS上來(lái)。如果想要體驗(yàn)一下ZFS，由于目前它和Solaris 10綁定在一起，所以需要下載最新版的Solaris 10 6/06 (http://www.sun.com/software/solaris/get.jsp)。

參考:

Solaris ZFS Administration Guide: http://docs.sun.com/app/docs/doc/819-5461?l=zh&q=ZFS

Solaris 10 Zone FAQ: http://www.sun.com/software/solaris/faqs/zfs.xml

Automatic Performance Tuning in the Zettabyte File System: http://tesla.hpl.hp.com/self-manage03/Finals/henson-self-tune.pdf