Booting Thin Client Diskless Workstation

Bootp, shorts for Bootstrap Protocol, is an UDP network protocol which is originally defined in RFC 951 to assign IP address for network clients. Bootp is well suitable to apply in diskless workstation, workstation without operating system installed, or simply called thin client.

Bootp is not DHCP! Although both of these two protocols sound similar at first thought, but they are technically different and could be co-exists in the same server or network segment.

Hospitality management system giant, Micros System Inc, makes good use of bootp in its high rank Point-Of-Sale system called Micros 8700 HMS.

When the diskless Micros PC Workstation power on, the bootp enabled network interface card will broadcast its MAC address to the network. When the bootp daemon running on the Micros host receives the broadcast packets, it will assign a valid IP address follow by transferring a DOS operating system image to the PC Workstation according to the MAC-IP-Image mapping maintained in the bootpd configuration file.

Once the image transferring (via tftp protocol) completed, the diskless PC Workstation starts to boot up with the OS image parking in memory segment that act as RAM-DISK. When the boot up completed, the Micros diskless PC workstation functions as if it is a normal desktop PC pre-installed with DOS OS.

Bootpd server and clients could be reside on different network segment by deploying bootp relay agent. To make thing simple or get it up and running right during initial roll out, put both bootpd server and client on the same network segment.

Checklist when thin client unable getting IP address:

1. Replace a known good unit of thin client to rule out possibilities of
   
   
• Faulty boot ROM embedded in NIC that is bootp enabled
• Faulty Ethernet patch cable
• faulty network access point or LAN point
  
  
2. Bootp daemon is not running. In Linux/Unix, execute
   
   ps -ef | grep bootpd
               or
   lsof -i | grep 67
   
   to confirm bootp daemon is running and listening to legacy port number (as shown in /etc/services file)
   
   
3. Incorrect MAC address to IP address mapping maintained in /etc/bootptab bootpd configuration file
   
   
4. ARP cache conflict at bootpd server. Executing the command
   
   arp -a
   
   to list the bootpd server arp cache. Confirm that there is no ARP cache conflict. To delete the conflict, for example conflict on IP address 192.168.1.3, execute command
   
   arp -d 192.168.1.3
   
   
5. Use cross-over patch cable or straight Ethernet cable and a hub to directly link up the bootpd server and client to form an simple isolate network. If it works in this simple network infrastructure, then get network experts sit in for assistant. There might be firewalls or routers that have blocked the UDP packets from reaching to bootpd server.

Related information:

• Tftp protocol in brief
  
  
• Host A sends an read request (RRQ) or write request (WRQ) packet to host B. The packet containing the filename and transfer mode.
• Host B replies with an acknowledgement packet (ACK) to WRQ or directly with a DATA packet in case of RRQ. The reply also serves to inform host A of which port on host B the remaining packets should be sent to.
• The source host sends numbered DATA packets to the destination host, all but the last containing a full-sized block of data. The destination host replies with numbered ACK packets for all DATA packets.
• The final DATA packet must contain less than a full-sized block of data to signal that it is the last. If the size of the transferred file is an exact multiple of the block-size, the source sends a final DATA packet containing 0 bytes of data.
  
  
• Search more related info with Google Search engine built-in

Repair Corrupted Outlook PST OST File

PST, known as Microsoft Outlook personal folder file or email archive file, used to archive emails out from the mail box at server side to a local storage or network drive.

OST, known as Microsoft Outlook offline folder file, allows user to work with Microsoft Exchange mail box in an offline mode. For example, emails composed, Contacts or Calendar changes, etc, will be storing in the offline folder. These changes made in offline folder will be automatically synchronize with Microsoft Exchange Server once hook up to the network - emails composed will be sending out immediately and Contacts or Calendar changes are updated to server side objects.

Both the Microsoft Outlook PST and OST files are believed using MSDE database engine.

MSDE is a light-weight freeware version of Microsoft SQL Server database engine that Microsoft offers to attract database users (especially MS Access users, developers, students, educators, etc) to develop database projects using Microsoft SQL Server. The latest release of MSDE is called SQL Server Express edition.

MSDE built with limitation of accessing up to 2GB worth of data only. The same limitation occurs in MS Outlook PST and OST file as well!

Watch the size of PST and OST file! If they getting fatty, trim them down quickly to save archives of email from hitting the 2GB limitation or a file corruption will happened soon! The best practice is to create multiple PST or OST files to categorize email archives. For those email with attachment, it is easily reaching the 2GB limitation. So, more PST or OST files are needed to archive such emails with attachment!

Office 2000 and higher with latest patches installed is nice enough to alert users with an error message and disallow users from adding or receiving new email item, so to safeguard PST or OST file to become oversize and corrupted. Earlier versions of MS Outlook does not display any error or warning messages and allow users to oversize the PST or OST file until corruption!

Microsoft offers a tool called PST2GB to recover a MS Outlook PST file that is corrupted after storing over 2GB worth of data. Microsoft alleged that PST2GB is not a tool that is 100% work at all time! If PST2GB does work, it does not recover all of the data (the truncated data is missing).

PST2GB merely create a truncated copy of the PST file to under 2GB. The copy that is left after the PST2GB completes does not have all the original data because the PST2GB forcibly cuts a user defined amount of data (below 2GB) from the PST file.

In brief,

1. Data or the emails archive after the truncation boundary will gone missing.
2. There must be enough disk space, 2GB free disk space if as maximum as possible of recovery desired.

Steps to recover corrupted PST file as per Microsoft KB296088 (applied to MS Outlook 97 to MS Outlook 2002)

1. Download the PST2GB from Microsoft Download Center
   
   
2. Extract the downloaded file 2gb152.exe to an empty folder for these five files - Msstdfmt.dll, Msvbvm60.dll, Pst2gb.exe, Readme.rtf, Readme.txt
   
   
3. Start the Pst2gb.exe program.
   
   
4. Click Browse to select the oversize PST file and then click Open.
   
   
5. Click Create, select the name and location of the truncated data file to be created, and then click Save.
   
   
6. Enter the amount of the data that intended to truncate in the PST file. There is no absolute ideal figure for this but for the best results is using 20 to 25MB, more or less. If that works, repeat the process and truncate the original oversize PST file by only 15MB. If that works, then try the process with 5MB. If 25MB does not work, repeat the process and truncate the original PST by 35MB. If the process does not work, increase the amount until the process is successful.
   
   
7. Run the Inbox Repair Tool scanpst.exe on the smaller PST file.
   
   
8. Open the repaired PST file in Microsoft Outlook.
   
   
9. (Recommended but optional) If the file opens, right-click the root folder of the PST, click Properties, and then click Compact Now to start the compression. For a file of this size, the compression may take approximately 4-8 hours.
   
   
10. If the file does not open, discard the truncated PST file, and repeat the process with the original PST file. Truncate more data than in the first attempt, and try the process again.
    
    

If the following error message arise when trying to run the PST2GB Utility

Run-time Error '713': Class not Registered. You need the following file to be installed on your machine. MSSTDFMT.DLL

To resolve this error, follow these steps:

1. Microsoft Windows 98, Microsoft Windows 98 SE, Microsoft Windows ME
   
   
1. Copy the MSstdfmt.dll file to the C:\Windows\System folder.
   
   
2. Open a command prompt, and then type the following command
   
   REGSVR32 C:\Windows\System\MSSTDFMT.DLL
   
   
2. Microsoft Windows NT, Microsoft Windows 2000, and Microsoft Windows XP
   
   
1. Copy the MSstdfmt.dll to the C:\<windir>\System32 folder.
   
   
2. Open a command prompt and type the following command
   
   REGSVR32 C:\<windir>\System32\MSSTDFMT.DLL
   
   where <windir> is either the WINNT or the Windows directory.

Related information:

• PST2GB from Microsoft official download site
• Inbox Repair Tool for MS Outlook 2000 to MS Outlook 2003
• Inbox Repair Tool for MS Outlook 97
• Inbox Repair Tool for MS Outlook 98
• OST Integrity Check Tool for Outlook 2000
• Mailbox Recovery for Microsoft Exchange 2000 Server
• Search more related info with Google Search engine built-in

Repair Corrupted Windows Boot.ini

Boot up to Windows Recovery Console and execute command bootcfg to repair corrupted or recreate missing Windows boot.ini file.

The bootcfg command able to scan hard disks for installation of Windows NT 4.0 and above and then add them to existing boot.ini file. The command also able to rebuild a new boot.ini file if one does not exist.

A brief of bootcfg command usage and syntax

• bootcfg /add scans the computer for Windows systems installed (for example Windows 2000 and Windows XP in a dual boot setup), displays the results to choose and add it to the Boot menu.
• bootcfg /rebuild iterates through all Windows installations found in the PC, allows user to specify which installations to rebuild the boot.ini file.
• bootcfg /list reads the boot.ini file and displays the operating system identifier, the operating system load options, and the operating system location (path).

Related information:

• The bootcfg command syntax and usages
• Search more related info with Google Search engine built-in

Sending Windows Console Message

Windows Me or 9x comes with one handy network chatting program called Winpopup. Simple GUI allows user at one computer to chat over the network with counterparts sitting at another networked Windows.

However, there is not similar Winpopup replacement for Windows 2000 and above. There are two ways to send a message, better known as console message or Windows Alerts, to networked system running Windows 2000 and above.

1. Via the Computer Management window
   
   
1. Right-click on the My Computer icon on Desktop
2. Click on the Manage option from the pop up context menu
3. Click on the Action menu of Computer Management window
4. Goto All Tasks option
5. Click on the Send Console Message... option to call up Send Console Message window.
   
   
   
   
2. Via Command Prompt
   
   
1. Click on the Start button
2. Click on the Program menu
3. Click on the Accessories menu
4. Click on the Command Prompt application
5. At the Command Prompt window, type
   
   net send 192.168.1.2 "testing messages"
   
   to send a messages "testing messages" to PC with 192.168.1.2 IP address.
   
   It is possible to replace IP address with DNS name or domain name to send console message to all workstations of the said domain.
6. Type net help send for more syntax and usage information.
   
   

Related information:

• Search more related info with Google Search engine built-in

Restart VNC Remotely

Opsss! Can't VNC over to remote hosts!

Might need to restart the VNC server, but how?

• Restart Windows-based (Windows 2000 and above) VNC server
  
  
1. Right-click the My Computer icon on Desktop
   
   
2. Click the Manage option from the pop up context menu
   
   
3. Click the Action menu of the Computer Management windows
   
   
4. Click the Connect to another computer... option
   
   
5. Type the IP address or DNS name of the target PC running the VNC server
   
   
6. Enter the login authentication info when prompt
   
   
7. After connect successfully, click the Services and Applications on the left panel.
   
   
8. Click the Services option
   
   
9. Search for VNC Server service on the right panel, right-click on it, and click Restart option to restart the VNC server.
   
   
• Restart Linux-base VNC daemon
  
  
1. Telnet or ssh over to target host that running the VNC daemon
   
   
2. Type the command vncserver -kill:1 to kill the VNC daemon running on DISPLAY:1, for example.
   
   
3. Type vncserver :1 to bring up the VNC daemon running on DISPLAY:1 again.
   
   
4. To ensure VNC daemon startup listening for connection, type
   
   netstat -ant | grep 5901
   
   where 5901 is the legacy VNC daemon listening port of DISPLAY:1 in the previous step. If the port is open and listening means that VNC daemon is up and running successfully.

Related information:

• Running VNC daemon on Linux
• Search more related info with Google Search engine built-in

Install Recover Console To Boot Menu

Recover Console is not install to local hard disk by default during Windows installation.

In order to access to Recovery Console, normally practice is to boot up the system from the appropriate Windows setup CD. If the system is running on Windows XP, use the Windows XP setup CD. Note that Recover Console only available in Windows 2000 and above.

Other than access the Windows Recovery Console from bootable Windows setup CD, it is possible to install the Windows Recovery Console to local hard disk and configure it to appear as one of the Windows boot up option.

Install Recovery Console to local hard disk and enable Recovery Console as part of the Windows boot up menu option:

1. Click on the Start button
   
   
2. Click on the Run menu
   
   
3. Type D:\i386\winnt32.exe /cmdcons by assuming D: drive is CD-ROM drive letter in which the Windows XP Setup CD is loaded.
   
   
4. Click OK button and then follow the instructions on the screen to complete the straight forward setup and restart the computer at the end of setup process.
   
   
5. After the Windows reboot, edit the file C:\boot.ini with notepad editor. Note that this file is hidden system file which is not "appear" in Windows Explorer by default, unless turning on the view hidden file options.
   
   
6. If view hidden file option is not turn on, turn it on by
   
   
1. Open My Computer
2. Click on the Tools menu
3. Click on the Folder Options
4. Click on the View tab
5. Click on the Hidden files and folders
6. Click to select Show hidden files and folders option button.
7. Click to clear Hide protected operating system files check box
8. click OK to complete the turning on view hidden file procedures.
   
   
7. At the bottom of the file, append this line
   
   C:\cmdcons\bootsect.dat="Recovery Console" /cmdcons
   
   Note that changing the description "Recovery Console" to whatever meaningful name is possible.
   
   
8. Save and exit the edited file. On the next system boot up, notice that there is one new boot option called Recovery Console in the Windows boot up menu.

Related information:

• Tweaking Windows Recovery Console
• Search more related info with Google Search engine built-in

Microsoft Freeware Visual Studio Express

Yes! Effective 19 April 2006, all Visual Studio 2005 Express Editions are free permanently!



Microsoft Express Edition includes a wide range of Microsoft flagship development tools such as MS SQL Server 2005, Visual Basic 2005, Visual C# 2005, Visual C++ 2005, Visual J# 2005, Visual Web Developer 2005. As long as Express keyword attached, such as Visual Studio 2005 Express Editions, it is a genuine Microsoft freeware edition.

For those who familiar with MSDE, SQL Server Express is the replacement. Microsoft alleged that the name MSDE was confusing to customers and partners because many did not realize that it was associated with SQL Server. By changing the name from MSDE to SQL Server Express there will be less confusion among customers and partners.

Everyone could use the Expression edition at no cost for the purpose of testing, learning, and even compile and sell the development project. Before this, Microsoft freeware such as Visual Basic Learning edition couldn't compile development into executable.

Related information:

• Product comparison of Visual Studio 2005
• Visual Studio Express frequently asked questions
• Price comparison of Visual Studio 2005 products
• Search more related info with Google Search engine built-in

System And Network Monitoring Freeware

Nagios is the answer!


It is licensed under the terms of the GNU General Public License Version 2 as published by the Free Software Foundation.

Nagios is a powerful system and network monitoring application. It monitors hosts and services specified, alerting administrators when threshold triggered, and when they recover to healthy state.

Nagios is only available in Linux or UNIX variants. Although, it could helps to monitor Windows servers as well via the Windows version of Nagios client.

Nagios features:

1. Monitors network services such as SMTP, POP3, HTTP, NNTP, PING, etc.
2. Monitors server resources such as processor load, disk usage, etc.
3. Simple plugin design that allows users to easily customize own service checks.
4. Parallelized service checks.
5. Ability to define network devices hierarchy using "parent" hosts, allowing detection of and distinction between network devices that are down and those that are unreachable.
6. Notifications to contacts of email, pager, or user-defined method, when service or host status change.
7. Ability to define event handlers to be run during service or host events for proactive problem resolution.
8. Automatic log file rotation.
9. Support for implementing redundant monitoring hosts.
10. Optional web interface for viewing current network status, notification and problem history, log file, etc.

Related information:

• Nagios official site
• Nagios 2.0 documentation
• Nagios Plugin is the open project at Source Forge to create Nagios plugin
• Nagios Exchange is the official repository for third party Nagios plugin
• Nagios plugin development guidelines
• Search more related info with Google Search engine built-in

Internet Explorer Turns FTP Browser

FTP is a legacy file transfer protocol that has been widely used since the day of networked computing.

Other than using the serious typing of command line FTP client, such as the standard FTP client offers by all Windows system, Internet Explorer able to serve as GUI FTP browser too!

Follow these simple steps to turn IE into a graphical FTP client:

1. Click the Tools menu from Internet Explorer,
2. Click on Internet Options,
3. Click the Advanced tab,
4. Check the check box labeled as "Enable Folder View For FTP Sites",
5. Check the check box labeled as "Use Passive FTP". Set this option only if the PC is behind a firewall.
6. Click OK button to complete the setting.
7. Now, IE is ready to serve as graphical FTP browser. For example, type ftp://keith@188.8.1.10 in the IE address bar and press ENTER to instruct IE connect to FTP server 188.8.1.10 using FTP user account keith. Enter the password when prompt.
8. Click OK and wait. After successful authentication, an interface similar to Windows Explorer shown. Copy files or folders as usual!

Related information:

• Search more related info with Google Search engine built-in

Tweaking Windows Recovery Console

The Windows Recovery Console is designed to help system administrators recover Windows-based computer that fails to start up properly. It is available only in command prompt. Hence the name "Console" attached. It looks like the Windows 9x boot disk, but Windows Recovery Console is more powerful and features rich than the old Windows boot disk.

Basically, Windows Recovery Console allow system administrators to:

1. Copy, rename, replace, and access to operating system files and folders
2. Enable or disable Windows services for next system bootup
3. Repair the file system boot sector or the Master Boot Record (MBR)
4. Create and format partitions

By default setup, Windows Recovery Console with Administrator account logon allows access to only

1. the root folder
2. the %SystemRoot% folder and sub folders of the Windows installation
3. the Cmdcons folder
4. the removable media drives such as the CD-ROM drive or the DVD-ROM drive

Trying access to folders other than those listed above will rejected with an "Access Denied" error message. Besides that, Windows Recovery Console disallow copy files from local hard disk to removable storage such as floppy disk. However, Windows Recovery Console allow copy files from removable storage to local hard disk or copy files from one hard disk to another hard disk.

Although, limitations imposed on default setup that stated above could be resolved by

1. First, enable setting in Local Security Policy.
   
   
   1. Click on Start button,
   2. Click on Run menu,
   3. Type gpedit.msc and click OK button,
   4. Click on Computer Configuration, Windows Setting, Security Setting, Local Policies, Security Options,
   5. Look for "Recovery Console: Allow floppy copy and access to all drives and all folders" policy on the right pane and double-click it,
   6. Select Enabled,
   7. Click OK
   
   Note! As a security measures, it might be wise to double-click on "Recovery Console: Allow automatic administrative logon" policy too and disable it.
   
   
2. Second and last, boot up to Windows Recovery Console, logon with Administrator login account, and execute these two commands:
   
   
   1. set AllowRemovableMedia = true
   2. set AllowAllPaths = true
      
      
   It might be useful to turn on these two features too:
   
   
   3. set AllowWildCards = true to allow wildcard support for some commands such as del.
   4. set NoCopyPrompt = true to disable prompt when overwriting an existing file.

Related information:

• Install Windows Recovery Console
• Search more related info with Google Search engine built-in

Restart Disabled Windows Services

What could be done besides rebooting Windows server when a particular Windows service become unavailable to start, stop, pause, resume, or restart?

Restarting a Windows service, particular a poorly coded third party Windows service, may turns out to become unable to start, stop, pause, resume, or restart, after the service timeout and fail to startup successfully again. All these five common actions or tasks are dimmed and become unavailable. Restart the Windows server is not the only way, and might not advisable too, to resolve the problem.

Try this before deciding to reboot the Windows server:

1. Right-click on the Windows service,


2. Select property,


3. Set the Startup type to Disabled,


4. Click OK,


5. Set to Startup type again to either Manual or Automatic,


6. Click OK again,


7. Now, this particular Windows service might able to perform one of the five common actions again. Restart the Windows server if these do not work perfectly too.

Fine Tuning Nagios Performance

These optimization tips are suggested by Nagios official documentation. It might be useful to fine tune Nagios for optimum performance and effective monitoring service.

1. Enabling aggregated status updates with the aggregate_status_updates option to greatly reduce the load on the monitoring host especially when monitoring a large number of services. The downside of this approach is getting delay notification on status change.


2. If standard status log is used instead of aggregated status updates, consider putting the directory where the status log is stored on a ramdisk. Ramdisk helps to speed thing up by saving a lot of interrupts and disk thrashing.


3. Use max_concurrent_checks option to restrict the number of maximum concurrently executing service checks. Nagios is overloaded if the extinfo CGI showing high latency values, say more than 10 seconds, for the majority of service checks.


4. The overhead needed to process the results of passive service checks is much lower than that of normal active checks. Passive service checks are only really useful if there are some external applications doing some type of monitoring.


5. Compiled plugin (C/C++) runs more efficient and faster than interpreted script (Perl, etc) plugins. If really want to use Perl plugins, consider compiling them into true executable using perlcc utility which is part of the standard Perl distribution or compiling Nagios with an embedded Perl interpreter.
   
   In order to compile in the embedded Perl interpreter, set the --enable-embedded-perl option in the configuration script before compiling Nagios. In addition, use the --with-perlcache option to enable embedded interpreter caching the compiled Perl scripts for later reuse.


6. The check_ping plugin used to check host states will performs much faster if break up the checks. This is due to the fact that Nagios judges the status of a host after executing the plugin once.
   
   Hence, it would be much faster to set the max_attempts value to 10 and only send out 1 ICMP packet each time, instead of specifying a max_attempts value of 1 in the host definition and having the check_ping plugin send 10 ICMP packets to the host.
   
   However, the pitfalls of this arrangement will happens when the hosts are slow to respond may be assumed to be down. Another option would be to use a faster plugin check_fping as the host_check_command instead of check_ping.


7. Do not schedule regular checks of hosts unless absolutely necessary. Set the value to 0 for check_interval directive in the host definition to disable regular checks of a host. Use a longer check interval if really need to have regularly scheduled host checks.


8. Disable the use_aggressive_host_checking option to speed up host checks. The trade off is that host recoveries can be missed under certain circumstances.


9. Set the command_check_interval variable to -1 if running a lot of external commands, i.e passive checks in a distributed setup, will cause Nagios to check for external commands as often as possible. This is important because most systems have small pipe buffer sizes (4KB). If Nagios doesn't read the data from the pipe fast enough, applications that write to the external command file (the NSCA daemon) will block and wait until there is enough free space in the pipe to write their data.


10. System configuration / hardware setup directly affecting how the operating system (and Nagios application) performs. CPU and memory speed are obviously factors that affect system performance, but disk access is biggest bottleneck. Don't store plugins, status log, etc on slow storage medium such as old IDE drives or NFS mounts. Always opt to use UltraSCSI drives or fast IDE drives whenever possible.
    
    Note! Many Linux installations do not attempt to optimize IDE disk access. Use hdparam to change the IDE hard disk access parameters to gain speedy features of the new IDE drives.

Tweaking Windows Server LargeSystemCache

LargeSystemCache determines whether Windows 2000 Server should maintains a standard size or a large size file system cache, and influences how often the system writes changed pages back to hard disk.

Increasing the size of the file system cache generally improves server performance, but it reduces physical memory space available to applications and services. In addition, writing system data less frequently minimizes use of the kernel disk subsystem, but the changed pages occupy memory that might otherwise be used by applications.

LargeSystemCache is DWORD registry data type that could be located at registry path

HKLM\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management

Setting LargeSystemCache to 1 (system default)

Establishes a large system cache working set that can expand to physical memory, minus 4 MB, if needed. The system allows changed pages to remain in physical memory until the number of available pages drops to approximately 250. This setting is recommended for most computers running Windows 2000 Server as file server on large networks.

Setting LargeSystemCache to 0

Establishes a standard size file system cache of approximately 8 MB. The system allows changed pages to remain in physical memory until the number of available pages drops to approximately 1,000. This setting is recommended for servers running applications that do their own memory caching, such as Microsoft SQL Server, and for applications that perform best with ample memory, such as Internet Information Services web server.

Other than access to registry via regedit.exe and edit directly, alternative method to tweak LargeSystemCache is by

1. accessing to the Server Optimization tab in Network And Dial-up Connections,
2. right-click My Network Places,
3. click Properties,
4. right-click Local Area Connection,
5. click Properties,
6. click File And Printer Sharing For Microsoft Networks,
7. and then click the Properties button,
8. to set the LargeSystemCache to 0, select the Maximize Data Throughput For Network Applications option,
9. to set the LargeSystemCache to 1, select Maximize Data Throughput For File Sharing.

The default setup of Windows 2000 Server initialize LargeSystemCache to 1 which is ideal when running as file server. However, setting LargeSystemCache to 1 can degrade service performance. As such, it is not appropriate when running as application servers such as Web server, SQL server, Exchange server. In this case, reset LargeSystemCache to 0 by selecting the Maximize Data Throughput For Network Applications option in Network And Dial-up Connections.

Compare And Find Best Compression Format

Compression ratio depends on data and algorithm used for compression. Compression speed counts on CPU power and data compression algorithm in used. Some compression utilities such as 7za, gzip, bzip2, etc, come with options to set level of compression. Setting to higher level of compression will means more time taking to compress and decompress too!

Follow the links below to the comparison of various file compression formats. Find the best compression scheme that suit better for a particular application.

• Lzop official site
• Rzip official site
• 7za / 7-Zip / LZMA related article
• Maximum Compression benchmark
• Practical compressor test benchmark
• Ultimate command line compressor benchmark
• Linux compression tools benchmark. Find the balance between level of compression ratio and time require to complete the compression process.

Excerpt from the source:

lzop is the fastest tool. It finishes about three times faster than gzip but still compresses data almost as much. It finishes about a hundred times faster than lzma and 7za.

Get even higher compression ratios by combining lzma with tar to increase storage space effectively by 400%.

The data compression tool with the best trade-off between speed and compression ratio is rzip. With compression level 0, rzip finishes about 400% faster than gzip and compacts data 70% more. Rzip default compression level is another top performer too as it can increase effective disk space by 375% but in only about a fifth of the time lzma can take.

Rzip accomplishes this feat by using more working memory. Whereas gzip uses only 32KB of working memory during compression, rzip can use up to 900MB! But that's okay since memory is getting cheaper and cheaper.

7-Zip Better File Archiver Freeware

7-Zip is a full function file archiver freeware!

7-Zip default to compress files in .7z compression format using LZMA compression algorithm.

LZMA, shorts for Lempel-Ziv-Markov chain-Algorithm, is a data compression algorithm developed on 2001. It uses a dictionary compression scheme similar to LZ77 (such as Gnuzip - better known as gzip in Linux world) but features with

• high compression ratio
• variable dictionary size up to 4GB
• compressing speed at about 1MB/s and decompressing speed at about 10-20MB/s on 2GHz CPU
• little memory require for decompressing depends on dictionary size
• small code size for decompressing at about 5KB
• supporting multi-threading and Intel Pentium 4 HT technology

Besides supporting 7z compression format, 7-Zip too able to compress and decompress some other popular compression formats.

• Supported compression file formats:
  7Z, ZIP, GZIP, BZIP2 and TAR
• Unzip compressed file formats:
  7Z, ZIP, GZIP, BZIP2, TAR, RAR, CAB, ISO, ARJ, LZH, CHM, Z, CPIO, RPM, DEB, and NSIS

While the classic Winzip, WinRAR, PowerArchiver, etc discontinue as true freeware, 7-Zip becomes better alternative freeware of file archiver as it is distributed under the GNU LGPL, with exception for the RAR plugin.

Others attractive features of 7-Zip such as:

• Supports files size up to 16000000000GB
• Unicode file name
• Self-extracting capability for 7z format
• Integration with Windows Shell
• Ability of using any compression, conversion or encryption method
• Multilingual interface up to 63 languages at time of writing.
• Available in various platforms such as both Windows 32-bit and 64-bit version, Unix, FreeBSD, Redhat, Fedore Core, Debian, Gentoo, Mac OS X, BeOS etc

DisablePagingExecutive Boost Windows Performance

Tweaking Windows core performance by editing registry key called DisablePagingExecutive only if

1. plenty of memory installed, e.g. 1 GB RAM or more
2. most of the memory being unused or idle on most of the time (wasting resource!), and
3. Windows 2000 and above (Windows XP, Windows 2003) is running.

DisablePagingExecutive is a DWORD data type that could be located at registry path

HKLM\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management

The initial setup of Windows XP default DisablePagingExecutive value to zero. Setting this value to 1 to enable Windows core to fully utilize the huge memory installed. Tweaking this registry key benefits driver debugging too as all of the code and data are always memory resident. It also improves Windows system core performance by preventing high frequency of disk read in order to get code and data out from hard disk to memory for processing!

Related information:

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Unzip RAR With ExtractNow Freeware

ExtractNow is a great non-adware freeware used to decompress RAR compression file format!

As its name suggests, ExtractNow is merely an decompressing utility and is not a complete archival software. Nevertheless, this simple free utility is more than enough to satisfy today most decompressing functions. Other than supporting RAR compression file format, ExtractNow also support today majority compression file format such as ZIP, ISO, BIN, IMG, IMA, IMZ, 7Z, ACE, JAR, GZ, LZH, LHA, and SIT!

ExtractNow developer suggest not to bundle DLL that used to enable SIT compression file format support in its installer so as to reduce (installer) file size. Having say that, separate download of DLL is needed if expected to enable SIT support in ExtractNow.

Related information:

• ExtractNow official site
• Click here to separate download DLL to enable SIT file compression support
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Sharing Big File With File Splitter

Email a big file of few megabytes as attachment is never a good idea as it will likely to hang up the email server. Because of that, most email servers are likely configured to not relay or process email with non friendly attachment too. If it is really need to email such attachment,

• Split the file into pieces of smaller size with file splitter such as File Chopper.
• Compress the file to highest possible compression ratio and creating span disk (support by most zip utilities such as WinRar & Power Archiver)
• Upload the file to public file server such as upload.com and rapidshare.de that offers file sharing services.

  CAUTION! It is better to zip the files with strong encryption before uploading to any public file sharing providers. Zip the files with encryption helps to reduce file size as well as protect sensitive data from the eyes of non expected readers!

• Combination of the three method - split the file, compress it with password encryption, and host the split-compressed file to public file server.
  
  File splitter is preferable than span disk feature of zip utilities as file split could be rejoined with Windows built-in command whereas "span disk" require the receiving end to have similar zip program installed.

Related information:

• File Chopper is a tiny file splitter program that able to chop a file into arbitrary file size and automatically generate a MS-DOS batch file used to rejoin the pieces of file back to its original file. The batch file is using Windows built in DOS copy command to do the job. For example, typing
  copy /b File.1 + File.2 WholeFile.exe
  to rejoin split files called File.1 and File.2 back to its original and workable file called WholeFile.exe
• Uploading.com only allow unlimited download at certain countries or registered users only. Downloading speed is quite fast as at time of writing.
• Rapidshare.de works similar to uploading.com
• Using Lycos Mail account. The redesign of Lycos Mail upgraded to allow unlimited attachment size as claimed in its official site, provided not exceeding the default 3GB email storage space allocated to each email account. Although, the recipient's email system might not accepting such emails with huge attachment size. So, use Lycos Mail to send email with unlimited attachment size only to recipient's Lycos Mail email account! Perhaps, this is the Lycos Mail's intention to get more users to attach with Lycos Mail and not the others like Yahoo! Mail or Gmail!
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Using VNC And Redhat Linux

VNC shorts for Virtual Network Computing which is based on Remote Frame Buffer (RFB) protocol. VNC enable any VNC compatible clients running on any platform to access remotely, in graphical mode, to any VNC compatible server running on any platform!

For example, a VNC client running on Windows XP able to remote access to the Redhat Linux X windows via VNC daemon running on Redhat Linux, or the Redhat Linux VNC client able to access to Windows XP and run the Windows program in Windows XP via the VNC session.

The term daemon is normally refers to Linux/Unix-based server application/process. So as here. And the term "server" is then refers to a Windows-based server application/process.

VNC provides not only GUI remote access but also persistent desktop where the long running program or unfinished editing works could be kept running while VNC session is closed. User could reconnect back later at some other places and straight away continue to work on the incomplete tasks.

However, there is a different in handling convention VNC session between Linux to Windows and Windows to Linux. When access from Linux VNC client to Windows VNC server, the screen seen in Linux VNC client is the same as one see in front of the real physical GUI console. When a Windows VNC client connects to Linux VNC daemon such as VNC Server, the screen seen in Windows VNC client is different from the real physical GUI console. This happens because the Linux X windows use the default :0 display (X server screen number) on startup and the port is not sharable with other sessions. The work around is by using x11vnc or the Redhat bundled Vino as VNC daemon.

Vino allow legacy VNC client access directly to the :0 display. For example, Redhat Enterprise Linux ES 4 comes with vino RPM package. Once installed, the Vino is called Remote Desktop and normally grouped under Preference menu. Its simple GUI configuration make it easier to startup the Vino's VNC daemon!

VNC Server is bundled with all Redhat Linux distribution. Once installed, start the VNC Server by typing vncserver at command prompt. The vncserver command, is actually a shell scripts file, bring up the first VNC Server daemon listening to TCP port 5801 & 5901 by default. To bring up second VNC Server daemon, specify a port number other than the default. For example, type vncserver :2 to bring second daemon listening to TCP port 5802 & 5902. Port number starting from 5801 is meant for Java-enabled web browser connection, while port number starting from 5901 is meant for legacy VNC client connection. Although VNC Server could not directly connecting to :0 display by default as Vino or x11vnc do, this feature could be enabled by using VNC loadable module for the X Window system or upgrade to VNC Server version 4.x.

x11vnc works like Vino but has much more features bundled such as built-in SSL encryption/authentication, file transfer, etc. x11vnc is written in plain C language and uses only standard libraries. So, there is no compatibility and performance issues by using x11vnc as VNC daemon, indeed!

Connecting from VNC client of any platform to Windows VNC server is quite straightforward. Just type the IP address of the Windows VNC server in VNC client will do. However, a combination of IP address and display port is used to connecting VNC client of any platform to Linux VNC daemon. The display port number is taken from the last 2 digits of Linux VNC daemon listening port number (ignore leading zero if any). For example, type http://10.170.46.111:5801 at any Java-enable web browser in order to connect to a Linux VNC daemon that listening to port 5801 or type 10.170.46.8:1 at any legacy VNC client in order to connect to Linux VNC daemon listening to port 5901.

Related information:

• x11vnc official site
• VNC Server v4.x official site
• TightVNC VNC utilities
• UltraVNC VNC utilities
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What Happen When Deleting A File

What happen to a file when deleting it from Windows? The native Windows OS delete function simply remove the file entry (complete path and filename) from directory entries. The file's data content, however, is still remain untouched in the storage area. That is why to copy a file of few hundred megabytes take some minutes while deleting it takes just few seconds.

Disk formatting isn't different. Unless low level format or Zero Fill is performed, an advanced undelete utilities able to recover data from a hard drive formatted with high level or native disk format utilities. With low level format, the entire hard disk is then filled with "zero", hence overwrite any data reside in the hard disk!

Note, it is better to use low format utilities from the respective hard disk manufacturer instead of generic low formatter (such as the BIOS built-in function) to avoid the hard disk unusable later!

Related information:

• How to undelete a file from Windows
• How to delete a sensitive file securely
• SDelete command line utility used to delete sensitive data securely
• Sure Delete Window GUI utility used to delete sensitive data securely
• Create File - Windows 2000 Resource kit used to generate empty file of arbitrary size up to 4GB (when running on Windows XP)
• WipeFree command line utility used to generate dump file to fill up free disk space where the deleted file reside
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