PCI, SCSI, and Fibre Channel

The PCI standard had its origins in the PC world, and has supplanted the two earlier standard microprocessor backplane buses�VME and Multibus. VME is, however, still used in real-time systems and in some process control applications. It started as a 16-bit bus and later grew to 32 bits; for the most part, VME-based systems used Motorola 68000-family microprocessors.

Multibus I was also a 16-bit bus initially, but Multibus systems tended to house Intel processors. While Intel extended the definition of Multibus I to 32 bits as Multibus II, the new version never saw wide adoption and disappeared fairly quickly.

We can summarize PCI�s major characteristics as follows:

� Two data transfer widths�32 bits and 64-bits

� Two clock rates�33MHz and 66MHz

� Various available bandwidths (133, 266, and 532 MB/sec), depending on clock rate and data width, and with burst-mode transfers

� The ability to support both 32 and 64 controllers on the same bus

� The ability to automatically discover the configuration of devices on the bus at system initialization (known as Plug and Play; this avoids tedious parameter setting in control tables)

� The ability to plug in and remove controllers without stopping the system, a capability known as hot plug.

PCI offers�even in its slowest version�substantially higher throughput than the earlier buses (and higher than MCA and EISA, too, which offered 33MB/sec and 40MB/sec respectively).

The significantly greater demands of more recent technologies, such as Gigabit Ethernet or Fibre Channel, have led to a proposal for a first extension to PCI, called PCI-X, with 32- or 64-bit data widths running at 66, 100 or 133MHz. The bandwidth of a 64-bit, 133MHz PCI-X interface is 1064MB/sec. Along with the physical enhancements, the bus protocol has also been improved in order to enhance efficiency.

The capabilities have been further extended into PCI-X 2.0, whose specifications were approved early in 2002. The goals of PCI-X 2.0 may be summarized as:

� Meet performance needs with an interface capable of handling 64-bit data widths running at 266 or 533MHz and with a throughput of 2128 or 4256 MB/sec respectively

� Support the use of earlier-generation cards to protect earlier investments (of course, this simply means that old cards must work with the new bus; a PCI-X 2.0 system with a mix of cards meeting earlier specifications and cards meeting 2.0 specifications will run at the speed of the slowest card)

� Become an industry standard

� Integrate well with the InfiniBand initiative (see below)

These various buses all represent the classical way to connect up peripherals and controllers �New I/O Structures: InfiniBand�we will examine the limitations of the classical approach and show why a new I/O architectural approach is called for.

Source of Information : Elsevier Server Architectures 2005

Understanding 64-Bit Computing

Since it was introduced for Windows operating systems, 64-bit computing has changed substantially. Not only do computers running 64-bit versions of Windows perform better and run faster than their 32-bit counterparts, they are also more scalable because they can process more data per clock cycle, address more memory, and perform numeric calculations faster. Windows 7 supports two different 64-bit architectures:

� x64 This architecture is based on 64-bit extensions to the x86 instruction set, which is implemented in AMD Opteron (AMD64) processors, Intel Xeon processors with 64-bit extension technology, and other processors. This architecture offers native 32-bit processing and 64-bit extension processing, allowing simultaneous 32-bit and 64-bit computing.

� ia64 This architecture is based on the Explicitly Parallel Instruction Computing (EPIC) processor architecture, which is implemented in Intel Itanium (IA64) processors and other processors. This architecture offers native 64-bit processing, allowing 64-bit applications to achieve optimal performance.

Sixty-four-bit computing is designed for performing operations that are memory intensive and that require extensive numeric calculations. With 64-bit processing, applications can load large data sets entirely into physical memory (that is, RAM), which reduces the need to page to disk and increases performance substantially. The EPIC instruction set enables Itanium-based processors to perform up to 20 operations simultaneously.

Currently, the prevalent firmware interfaces are:
� Basic input/output system (BIOS)
� Extensible Firmware Interface (EFI)
� Unified Extensible Firmware Interface (UEFI)

Itanium-based computers differ in many fundamental ways from computers based on the x86 and x64 specifications. While Itanium-based computers use EFI and the GUID partition table (GPT) disk type, computers based on x86 use BIOS and the master boot record (MBR) disk type. Computers based on x64 use UEFI wrapped around BIOS or EFI. This means that there are differences in the way you manage computers with these architectures, particularly when it comes to setup and disk configuration. However, with the increasing acceptance and use of UEFI and the ability of Windows 7 to use both MBR and GPT disks regardless of firmware type, the underlying chip architecture won�t necessarily determine what firmware type and disk type a computer uses. This decision is in the hands of the hardware manufacturer.

Source of Information : Microsoft - Windows 7 Administrators Pocket Consultant 2010

I/O

Neither systems architects nor computer architecture researchers have paid as much attention to I/O as they have to processors. The rationale for this lack of attention is completely unclear to us, since I/O is a key part of a system, being both a driver for system performance and an opportunity for value add�unlike processors, where the economies of scale predominate.

We provided a generic server model with the purpose of identifying the various interconnects of interest, mentioning the interconnects between processor, memory and I/O.

An I/O system comprises a number of elements.

As shown in this diagram, the various elements of a classical I/O subsystem are as follows:

� A system controller implementing the connection between processor(s), memory and the I/O bus(es). In practice, this is often a chip integrating two functions�a memory controller and an I/O controller.

� One or more I/O buses. The industry has converged on the PCI (Peripheral Component Interconnect) bus and its extensions.

� I/O controllers connected to an I/O bus. Peripheral devices�for example, disks directly connected to the system, long-distance network connections (WAN, for Wide Area Network) and local network connections (LAN, for Local Area Network) are connected to these controllers.

� Directly-attached magnetic peripherals (a configuration called DAS, for Directly Attached Storage), on specialized buses such as SCSI, which today is the standard for this purpose.

� Specialized networks are used for the connection of peripheral subsystems, such as disk subsystems (e.g., SAN, for Storage Area Network) or communications subsystems (WAN or LAN). In this domain, the industry is moving to Fibre Channel.

We will first be interested in buses used for I/O (principally PCI and its extensions) and in the connections between controllers and magnetic peripherals (SCSI and Fibre Channel�Arbitrated Loop, or FC-AL) and subsequently in Fibre Channel, used to connect to peripheral subsystems.

Later, we will look at the InfiniBand I/O proposal, which has some chance of gaining traction in the years to come. For this success to come about, widespread industry support will be vital; at the time of writing, we are still waiting for confirmation of such commitment from an appropriate spectrum of industry players. For InfiniBand, we will concentrate on the functionality of I/O interfaces and the optimizations appropriate for communications in a loosely-coupled system, with an emphasis on clusters. Since data is the vital and central element of business information technology, the characteristics of the storage systems used are important factors in the choice of servers. Since data needs to be directly accessible�that is, on-line�permanently, both within a company and outside it (through the Internet), storage systems have become an essential part of a server. Trends in storage subsystems are ever-increasing capacity, performance, and availability, coupled with steadily reducing cost per gigabyte.

Communications support�both local and wide area�also has increasing importance. Reflecting this, specialized subsystems connected to servers have been developed.

Source of Information : Elsevier Server Architectures 2005

Naked Gaming

Good-bye, controller: an Xbox upgrade reads natural gestures

When Nintendo�s Wii game console debuted in November 2006, its motion-sensing handheld �Wiimotes� got players off the couch and onto their feet. Now Microsoft hopes to outdo its competitor by eliminating the controller altogether: this past January it revealed details of Project Natal, which will give Xbox 360 users the ability to manipulate on-screen characters via natural body movement. The machine-learning technology will enable players to kick a digital soccer ball or swat a handball simply by mimicking the motion in their living room.

Microsoft, which announced its ambitious Xbox upgrade plan in June 2009, has not set a release date, but many observers expect to see Natal at the end of the year. It will consist of a depth sensor that uses infrared signals to create a digital 3-D model of a player�s body as it moves, a video camera that can pick up fine details such as facial expressions, and a microphone that can identify and locate individual voices.

Programming a game system to discern the almost limitless combinations of joint positions in the human body is a fearsome computational problem. �Every single motion of the body is an input, so you�d need to program near-infinite reactions to actions,� explains Alex Kipman, Microsoft�s director of innovation for Xbox 360.

Instead of trying to preprogram actions, Microsoft decided to teach its gaming technology to recognize gestures in real time, just like a human does: by extrapolating from experience. Jamie Shotton of Microsoft Research Cambridge in the U.K. devised a machine-learning algorithm for that purpose. It also recognizes poses and renders them in the game space on-screen at 30 frames per second, a rate more than sufficient to convey smooth motion. Essentially, a Natal-enhanced Xbox will capture movement on the fly, without the need for the mirror-studded spandex suit of conventional motion-capture approaches.

Training Natal for the task has required Microsoft to amass a large amount of biometric data. The firm sent observers to homes around the globe, where they videotaped basic motions such as turning a steering wheel or catching a ball, Kipman says. Microsoft researchers later laboriously selected key frames within this footage and marked each joint on each person�s body. Kipman and his team also went into a Hollywood motion-capture studio to gather data on more acrobatic movements.

�During training, we need to provide the algorithm with two things: realistic-looking images that are synthesized and, for each pixel, the corresponding part of the body,� Shotton says. The algorithm processes the data and changes the values of different elements to achieve the best performance.

To keep the amount of data manageable, the team had to figure out which were most relevant for training. For example, the system doesn�t need to recognize the entire mass of a person�s body, but only the spacing of his or her skeletal joints. After whittling down the data to the essential motions, the researchers mapped each unique pose to 12 models representing different ages, genders and body types.

The end result was a huge database consisting of frames of video with people�s joints marked. Twenty percent of the data was used to train the system�s brain to recognize movements. Engineers are keeping the rest in a �ground truth� database used to test Natal�s accuracy. The better the system can recognize gestures, the more fun it will be to play the game.

Of course, Microsoft is not the only company exploring gestural interfaces. Last May, Sony demonstrated a prototype unit that relies on stereo video cameras and depth sensors that, it says, could be used to control a computer cursor, game avatar or even a robot. Canesta, a company that makes computer-vision hardware, has demonstrated a system that lets couch potatoes control the TV with a wave of the hand and has partnered with computer manufacturers Hitachi and GestureTek to create gestural controls for PC applications.

Still, the controller should not disappear altogether, says Hiroshi Ishii, who is head of the Tangible Media Group at the M.I.T. Media Laboratory. �I�m a strong believer in having something tangible in your hand,� he says. Wiimote devices, moreover, provide haptic feedback, such as vibration or resistance, which makes the action more realistic. Even for activities like Natal�s soccerlike Ricochet game demo, Ishii points out, a player might miss the feeling of connecting with a physical object that a controller provides.

But Peter Molyneux, creative director of Microsoft Game Studios Europe, looks forward to a new breed of computer entertainment, because eliminating game controllers opens up more creative possibilities. �Natal is forcing me as a designer to think of this as a relationship between the player and a piece of technology,� he says. �We�re trying to make something that feels as if it�s alive.�

Source of Information :  Scientific American Magazine February 2010

Fedora 12 Enabling Authentication

In most situations, you will enable shadow passwords and SHA512 passwords (as selected by default) to authenticate users who log in to your computer from local passwd and shadow password files. To change that behavior, you can select the Use Network Login button during the Create User setup during Firstboot.

The shadow password file prevents access to encrypted passwords. SHA512 is an algorithm used to encrypt passwords in Linux and other UNIX systems. It replaces an algorithm called crypt, which was used with early UNIX systems. When you enable SHA512 passwords, your users can have longer passwords that are harder to break than those encrypted with crypt. You can also use MD5 or SHA256 for encrypting passwords, although these methods are less secure.

If you are on a network that supports one of several different forms of network-wide authentication, you may choose one of the following features (on the Authentication tab):

� Enable Kerberos Support � Tick this check box to enable network authentication services available through Kerberos. After enabling Kerberos, you can add information about a Kerberos Realm (a group of Kerberos servers and clients), KDC (a computer that issues Kerberos tickets), and Admin server (a server running the Kerberos kadmind daemon).

� Enable LDAP Support � If your organization gathers information about users, you can tick this check box to search for authentication information in an LDAP server. You can enter the LDAP Server name and optionally an LDAP distinguished name to look up the user information your system needs.

� Enable Smart Card Support � Tick this check box to allow users to log in using a certificate and key associated with a smart card.

� Fingerprint Reader � Tick this check box to allow users to authenticate using a fingerprint reader.

� Enable Winbind Support � Tick this check box to configure your computer to authenticate users from information retrieved from NTDOM or ADS servers.


In addition to the services just mentioned, you can also select from various ways of gathering distributed user information, if any of these methods are supported on your network.

� Configure Hesiod � If your organization uses Hesiod for holding user and group information in DNS, you can add the LHS (domain prefix) and RHS (Hesiod default domain) to use for doing Hesiod queries.

� Configure NIS � Select this button and type the NIS domain name and NIS server location if your network is configured to use the Network Information System (NIS). Instead of selecting an NIS Server, you can select the check box to broadcast to find the server on your network.

Source of Information :  Wiley - Adobe Fedora Bible 2010 Edition Featuring Fedora Linux

Fedora 12 Choosing Different Install Modes

Although most computers automatically install Fedora in the default mode (graphical), there may be times when your video card does not support that mode. Also, although the install process will detect most computer hardware, there may be times when your hard disk, Ethernet card, or other critical piece of hardware cannot be detected and you�ll need to enter special information at boot time.

The following is a list of different installation options you can use to start the Fedora install process. You would typically try these modes only if the default mode failed (that is, if the screen was garbled or installation failed at some point). For a list of other supported modes, refer to the /usr/share/doc/anaconda*/command-line.txt file (if you have a running Fedora system somewhere with the anaconda package installed) or press F1 through F5 keys to see short descriptions of some of these types.

To use these boot options, highlight the first entry on the boot menu and press Tab. When the boot command appears at the bottom of the screen, type the options you want at the end of that line and press Enter to boot the install process.

� text: Type text to run installation in a text-based mode. Do this if installation doesn�t seem to recognize your graphics card. The installation screens aren�t as pretty, but they work just as well.

� ks: Type ks to run a Fedora installation using a kickstart file. A kickstart file provides some or all of the installation option answers you would otherwise have to select manually.

� lowres: Type lowres to run installation in 640 x 480 screen resolution for graphics cards that can�t support the higher resolution. To choose a particular resolution, use the resolution option. For example: resolution=1024x768.

� noprobe: Typically, the installation process will try to determine what hardware you have on your computer. In noprobe mode, installation will not probe to determine your hardware; you will be asked to load any special drivers that might be needed to install it.

� mediacheck: Type mediacheck to check your DVD before installing. Because media checking is done next in the normal installation process, you should do this only to test the media on a computer you are not installing on. For Fedora Live CDs, select the Verify and Boot option to check the CD before booting.

� rescue: The rescue mode is not really an installation mode. This mode boots from DVD or CD, mounts your hard disk, and lets you access useful utilities to correct problems preventing your Linux system from operating properly.

� vnc vncconnect=hostname vncpassword=******: Run the install in VNC mode to step through the installation process from another system.

� dd: Type dd if you have a driver disk you want to use to install.

� askmethod: Type askmethod to have the installation process ask where to install from (local DVD/CD, NFS image, FTP, HTTP, or hard disk).

� nocddma: Type nocddma to turn off DMA. Errors with some CD drives can be overcome by turning off the DMA feature. This is a good option to try if an install CD or DVD you know to be good fails media check. You could also try ide=nodma to turn of DMA for all IDE devices.

� updates: Type updates to install from an update disk.

You can add other options to the linux boot command to identify particular hardware that is not being detected properly. For example, to specify the number of cylinders, heads, and sectors for your hard disk (if you believe the boot process is not detecting these values properly), you could pass the information to the kernel as follows: linux hdx=720,32,64. In this example, the kernel is told that the hard disk hdx has 720 cylinders, 32 heads, and 64 sectors. You can find this information in the documentation that comes with your hard disk (or stamped on the hard disk itself on a sticker near the serial number).

Source of Information :  Wiley - Adobe Fedora Bible 2010 Edition Featuring Fedora Linux

Choosing computer hardware to Install Fedora 12

This may not really be a choice. You may just have an old PC lying around that you want to try Fedora on. Or you may have a killer workstation with some extra disk space and want to try out Fedora on a separate partition or whole disk. To install the 32-bit PC version of Fedora successfully (that is, the version on the accompanying DVD), the computer must have the following:

� x86 processor � Your computer needs an Intel-compatible CPU. With the latest version, Fedora recommends that you at least have a Pentium-class processor to run Fedora. For a text-only installation, a 200 MHz Pentium is the minimum, while a 400 MHz Pentium II is the minimum for a GUI installation.

� DVD or CD-ROM drive � You need to be able to boot up the installation process from a DVD, CD-ROM, or other bootable drive. (You can also boot from a USB flash memory drive by using the livecd-tools package to build an installable image for your USB device from the live CD or another minimal boot image.) Once you have booted from one of the media just described, you can use the Internet or a LAN connection to install Fedora software packages from a server on the network, or you can figure out a way to copy the contents of the DVD to a local hard disk to install from there.

� Hard disk � The minimum amount of space you need varies depending on the installation type and packages you select. If you are an inexperienced user, you want at least 2.3GB of space so you can get the GUI (with some Office and Productivity apps) or 3GB if you want to do software development. Although different install types are no longer supported in Fedora, the following items roughly indicate how much disk space you need to install different types of desktop or server systems:
� Office and Productivity � Requires 2.3GB of disk space.
� Software Development � Requires 3.0GB of disk space.
� Web Server � Requires 1.1GB of disk space.
� Minimal � Requires at least 620MB of disk space.

� RAM � You should have at least 128MB of RAM to install Fedora (text mode only). If you are running in graphical mode, you will want at least 192MB. The recommended minimum RAM (for decent performance) for GUI mode is at least 256MB.

� Keyboard and monitor � Although this seems obvious, the truth is that you need only a keyboard and monitor during installation. You can operate Fedora quite well over a
LAN using either a shell interface from a network login or an X terminal. For the really advanced, it is even possible to do a graphical network install over VNC (virtual network computing), a serial console, or an integrated lights out (ILO) solution to do a headless install.

Fedora versions, are available for the AMD64 architecture and PowerPC. The minimum PowerPC hardware supported is a PowerPC G3/POWER3.
Supported PowerPC products include the Apple Power Macintosh (1999 or later), IBM 32-bit RS/6000, Genesi Pegasos II, as well as 64-bit G5 and POWER processors from IBM eServer pSeries computers. Check the Fedora Project download site for information on PPC versions of Fedora.

For other hardware, such as Intel Itanium and IBM mainframe, there are versions of Red Hat Enterprise Linux available (which you have to purchase from Red Hat, Inc.).

Source of Information :  Wiley - Adobe Fedora Bible 2010 Edition Featuring Fedora Linux

Install Fedora 12 From DVD, network, or hard disk?

When you install Fedora, the distribution doesn�t have to come from the installation DVD or CD. After booting the installation DVD, press Tab with the Install selection highlighted. Then type the word askmethod at the end of the boot command line displayed and press Enter. You are offered the choice of installing Fedora from the following locations:

� Local DVD or CDROM � This is the most common method of installing Fedora and the one you get by simply pressing Enter from the installation boot prompt.

� Hard drive � If you can place a copy of the Fedora distribution on your hard drive, you can install it from there. (Presumably, the distribution is on a hard drive partition to which you are not installing.)

� NFS directory � Allows you to install from any shared directory on another computer on your network using the Network File System (NFS) facility.

� HTTP� Lets you install from a Web page address (http://) or FTP site (ftp://).

If your computer doesn�t have a DVD drive, you can use the boot.iso CD image from http://download.fedoraproject.org/. Navigate to releases/12/Fedora/i386/os/images/ to get the boot.iso CD image file. Make a CD from this file and use that CD to start a network install (HTTP, FTP, or NFS). Just type linux askmethod at the boot prompt to begin the installation process.

If you don�t have a bootable DVD or CD drive, there are other ways to start the Fedora installation. Unlike some earlier Fedora and Red Hat Linux versions, Fedora doesn�t support floppy disk boot images (the Linux kernel is too large to fit on a floppy disk). Therefore, if you don�t have a bootable DVD or CD drive, you need to start the install process from some other medium (such as a USB device, PXE server, or hard drive).

The following specialty installation types also may be of interest to you:

� Boot CD � You can create a boot CD from the location mentioned above. Copy and burn the file boot.iso from the images directory. You can use the CD you create from that image to begin the install process if you have a DVD drive that is not bootable or if you have the Fedora 12 software available on any of the media described in the linux askmethod section.

� USB or other bootable media � If your computer can be configured to boot from alternate bootable media, such as a USB pen drive, that is larger than a floppy disk, you can use the livecd-tools package to build an installable image for your USB device from one of the Live CD or minimal boot images.

� Kickstart installation � Lets you create a set of answers to the questions Fedora asks you during installation. This can be a time-saving method if you are installing Fedora on many computers with similar configurations.

A Fedora Installation Guide is now available from the Fedora Project if you find you need further information. You can access the guide here:

http://docs.fedoraproject.org/install-guide/f12/en-US/html-single/

Source of Information :  Wiley - Adobe Fedora Bible 2010 Edition Featuring Fedora Linux