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  • Automatic desktop/work environment setup

    - by Alex
    I have this strange thing I am trying to do, so before I jump into it I was curious if someone knows about existing solution or maybe have an advice as far as implementation. I run a small software company and as it happens I often do very different type of work. When I do coding for Java project I need Eclipse running and maybe VM with something like ActiveMQ server or whatever, plus terminals to tail -F log files specific to the application, etc. When I do something like weekly progress review with my team I need a few browser windows open and a gedit to take notes and so on. Depending on the type of work I am doing I generally have all of the related apps open in multiple different Workspaces. So in the example above Eclipse would be open in Workspace 1, terminals would be sharing Workspace 2 and so on. What I am trying to do is to automate opening of all these applications, positinoning them on the screen and assigning them to proper Workspaces. My current idea consists of having a Shell script that launches specific apps depending on what type of work I am about to start doing. Is there anything to aid this type of automation? Or is my only option is just a shell scripting at this point? My current system is Ubuntu 10.04

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  • How do I make complex SQL queries easier to write?

    - by DragonLord
    I'm finding it very difficult to write complex SQL queries involving joins across many (at least 3-4) tables and involving several nested conditions. The queries I'm being asked to write are easily described by a few sentences, but can require a deceptive amount of code to complete. I'm finding myself often using temporary views to write these queries, which seem like a bit of a crutch. What tips can you provide that I can use to make these complex queries easier? More specifically, how do I break these queries down into the steps I need to use to actually write the SQL code? Note that I'm the SQL I'm being asked to write is part of homework assignments for a database course, so I don't want software that will do the work for me. I want to actually understand the code I'm writing. More technical details: The database is hosted on a PostgreSQL server running on the local machine. The database is very small: there are no more than seven tables and the largest table has less than about 50 rows. The SQL queries are being passed unchanged to the server, via LibreOffice Base.

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  • Local network cache of PHP and Apache2 on Win Server 2008 R2

    - by Ahmed Benlahsen
    Software configuration : I have a new server with Windows Server 2008 R2 installed via VMWare. I have installed Apache2.2, PHP5.2 and MySQL5.5 as separate packages. Issue : On my first installation of my application, all works great. When I updated some JS and CSS files and accessed my application again from a PC on local network, I got the old JS and CSS versions. When I access the same application on local server I got the latest versions of those files. Link of my application on local server is : http://localhost/BADIL Link of my application from local network is : http://LOCAL_SERVER_IP/BADIL I think that must be some cache but I don't know where. Maybe on Win Server 2008 R2 or on VMWare? The question is: Why, when I access my application on the server, everything works fine, but when I access the same application from a local network, I do not see the updated versions of JS and CSS files?

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  • Oracle VM VirtualBox 4.0 Now Available

    - by Paulo Folgado
    Delivering on Oracle's commitment to open source, Oracle VM VirtualBox 4.0 is now available, further enhancing the popular, open source, cross-platform virtualization software.   "Oracle VM VirtualBox 4.0 is the third major product release in just over a year, and adds to the many new product releases across the Oracle Virtualization product line, illustrating the investment and importance that Oracle places on providing a comprehensive desktop to datacenter virtualization solution," says Wim Coekaerts, senior vice president, Linux and Virtualization Engineering, Oracle. "With an improved user interface and added virtual hardware support, customers will find Oracle VM VirtualBox 4.0 provides a richer user experience." Part of Oracle's comprehensive portfolio of virtualization solutions, Oracle VM VirtualBox enables desktop or laptop computers to run multiple guest operating systems simultaneously, allowing users to get the most flexibility and utilization out of their PCs, and supports a variety of host operating systems, including Windows, Mac OS X, most popular flavors of Linux (including Oracle Linux), and Oracle Solaris. Oracle VM VirtualBox 4.0 delivers increased capacity and throughput to handle greater workloads, enhanced virtual appliance capabilities, and significant usability improvements. Support for the latest in virtual hardware, including chipsets supporting PCI Express, further extends the value delivered to customers, partners, and developers. Highlights of Oracle VM VirtualBox 4.0 include New Open Architecture - Oracle and community developers can now create extensions that customize Oracle VM VirtualBox and add features not previously available.Enhanced Usability - A new scalable display mode enables users to view more virtual displays on their existing monitors. Improvements to VM management, including visual VM previews, an optional attributes display, and easy launch shortcut creation enables administrators and power users to customize the interface to make it as simple or as comprehensive as required.Increased Capacity and Throughput - A new asynchronous I/O model for networked (iSCSI) and local storage delivers significant storage related performance improvements, while new optimizations allow larger datacenter-class workloads, such as Oracle's middeware, to be run on 32-bit Windows hosts for testing and demo purposes. Powerful Virtual Appliance Sharing Capabilities - Enhanced support for standards-compliant OVF appliances and added support for OVA format descriptors. All information about a VM may be stored in a single folder to facilitate easier direct sharing among VMs. Support for Latest Virtual Hardware - A new, modern virtual chipset supporting PCI Express and other hardware enhancements including high-definition audio devices helps ensure support for the most demanding virtual workloads.

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  • Caching API Proxy Server

    - by edc1591
    I need to have a server that caches API responses and then forwards them along to a desktop app. I don't really have much experience with this, so I have a few questions. First of all, what kind of server should I get? I already use Linode for my websites, so ideally I'd like to go with them. I expect to get anywhere from 30 million to 40 million requests to my proxy server each month. Will a 512 Linode be able to support that? Also, is there any software out there that does this already, or will I have to write my own? The API responses are roughly 10 KB each on average, so doing the math, that's a lot of data each month. Should I just add more transfer to whatever server I buy, or can I somehow compress the API responses before sending them off to the user? Thanks for any help.

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  • the brightness controls buttons are not working on my HP Dm3t notebook with windows xp, any suggetio

    - by Karim
    i have an HP dm3t notebook which normally comes with windows 7. after some time i figured out how to install Windows XP on it. but now i am facing a problem that the brightess controls dont work so i am unable to change the brightess. the strange thing is that all the other buttons (sound volume, mute, sleep , etc... ) works but not the 2 brightess controls. i already downloaded the "HP Quick Launch Buttons" so i am asking about suggesitions how can i enable these two buttons in windows XP or even if i can change the brightess using some kind of software. thanks

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  • Can you upgrade OEM Office with an OEM Upgrade

    - by LuckyLindy
    We have a bunch of computers at work that have OEM Office 2000. We have all the material, CDs, etc., and amazingly the computers still work well (they were top of the line when purchased in 2002). However, we'd like to upgrade to Office 2003, our corporate standard. We've found OEM Office 2003 upgrade software online for ~$60 apiece, which would save us thousands over installing retail upgrades or volume licenses. But can we do this? I haven't been able to get a clear answer from Microsoft or anyone else if OEM Upgrades can be applied by non-System Builders to OEM Office.

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  • Nested RDP and ILO/VMWare console sessions, latency and keystroke repetition

    - by ewwhite
    I'm working on a remote server installation entirely through ILO. Due to the software application and environment, my access is restricted to a Windows server that I must access through RDP. Going from that system to the target server is accomplished via HP ILO2 or ILO3. I'm trying to run a CentOS installation in an environment where I can't use a kickstart. I'm doing this via text mode, but the keystrokes are repeating randomly and it's difficult to select the proper installation options. For example: ks=http://all.yourbase.org/kickstart/ks.cfg ends up looking like: ks====httttttp://allll..yourbaseee.....org/kicksstart/ks.cccfg I'm doing this using Microsoft's native RDP client (on Mac and Windows). I've also noticed this before when running installations or doing remote work in nested sessions. Same for typing into a VMWare console in some cases. Is there a nice fix for this, or it it simply a function of the protocol(s)?

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  • I install Ubuntu 13.10 and reboot and im on KDE desktop?

    - by jgamer578
    Hi I'm Jacob and I have no idea what's going on. I installed Ubuntu 13.10 today and was playing around with it for a while and dl'd a bunch of apps from software center and stuff. Eventually I installed steam and (finally) got it working. I downloaded TF2 and had some weird issue where the screen got so distorted to the point I could not play. So I dl'd a driver for my graphics card from the additional drivers app (or whatever it's called) and when it was done I restarted my computer (because it said to.) When the PC booted up it loaded the KDE desktop and I have no idea why. I had unity before I rebooted. Ubuntu 13.10 is the only OS installed on my PC, and I still have all the apps that I downloaded, but I kinda like unity (I started using Ubuntu after they switched to unity) and want it back. Thanks for reading and any help in advance, Jacob.

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  • radius traffic accounting - what attributes do I use for traffic (and how)

    - by Mark Regensberg
    we are building a web front end for a internet access token management system that uses radius (freeradius) queried from a captive portal. Reason for building this part is the integration into the accounting and billing platform that operates behind the scenes (all other parts are currently available open source software) The structure is fairly standard, and setting up the basic bits were easy enough (authentication, traffic updates from the captive portal, account expiry date/times) - but I seem to have run out of ability when it comes to limiting an account by traffic consumed. So we can: set up usernames / passwords set expiry dates/times for a given user see the traffic for that user being accurately updated in RADACCT But we can't figure out the correct way/attribute to expire a user when they have consumed X octets of traffic. What attributes are used, or - maybe more accurately - what would be the correct way to use these attributes to limit an account to a certain volume of traffic? Any links to documentation appreciated - freeradius documentation doesn't seem to address the issue directly, or I'm looking in the wrong place... --mark

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  • Google Introduces Android Gingerbread and Nexus S Phone

    - by Gopinath
    Google today officially announced the availability of next version of Android(version 2.3) nicknamed “Gingerbread”. This is a long awaited upgrade to it’s smartphone platform from Google and below are the highlights of new features: Rich multimedia – including support for VP8 and WebM video and new audio effects. Support for front-facing cameras, SIP/VoIP and Near Field Communication (NFC). Enhancements for game developers, including new sensor types. You can read more about the release at Google blog post and watch this embedded video. Samsung Nexus S – The First Gingerbread Android Phone Samsung’s Nexus S is the first Android phone to be released with Gingerbread operation system. This is a phone that was designed with direct inputs from Google team and comes with a clean install of Android OS – no additional software layers from third party OEMs or carriers. Visit Nexus S site for more details This article titled,Google Introduces Android Gingerbread and Nexus S Phone, was originally published at Tech Dreams. Grab our rss feed or fan us on Facebook to get updates from us.

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  • List SQL Server Instances using the Registry

    - by BuckWoody
    I read this interesting article on using PowerShell and the registry, and thought I would modify his information a bit to list the SQL Server Instances on a box. The interesting thing about listing instances this was is that you can touch remote machines, find the instances when they are off and so on. Anyway, here’s the scriptlet I used to find the Instances on my system: $MachineName = '.' $reg = [Microsoft.Win32.RegistryKey]::OpenRemoteBaseKey('LocalMachine', $MachineName) $regKey= $reg.OpenSubKey("SOFTWARE\\Microsoft\\Microsoft SQL Server\\Instance Names\\SQL" ) $regkey.GetValueNames() You can read more of his article to find out the reason for the remote registry call and so forth – there are also security implications here for being able to read the registry. Script Disclaimer, for people who need to be told this sort of thing: Never trust any script, including those that you find here, until you understand exactly what it does and how it will act on your systems. Always check the script on a test system or Virtual Machine, not a production system. Yes, there are always multiple ways to do things, and this script may not work in every situation, for everything. It’s just a script, people. All scripts on this site are performed by a professional stunt driver on a closed course. Your mileage may vary. Void where prohibited. Offer good for a limited time only. Keep out of reach of small children. Do not operate heavy machinery while using this script. If you experience blurry vision, indigestion or diarrhea during the operation of this script, see a physician immediately. Share this post: email it! | bookmark it! | digg it! | reddit! | kick it! | live it!

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  • pfSense + DDoS Protection

    - by Jeremy
    I run a gaming community on a colo with a 100Mbps port. I want to buy a very cheap 35 dollar server with the same 100Mbps port, and run pfSense to use as a hardware firewall. I'm dealing with a bunch of 14 year old kids that have access to botnets, so it can become a bit necessary to get something like this. My overall question, is using pfSense on a cheap identical datacenter/port speed server worth it to actually block DDoS attacks? A bit more into detail since I assume you will ask this, the attacks we receive are normally around 1Gbps. We currently run CentOS using CSF Firewall, and even when using a software firewall, we block 500Mbps UDP floods, or just generic attacks pretty easily. Thanks, - Necro

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  • Smarter System Alerts

    - by mellowsoon
    We have a pretty simple system setup, where I get text messages when there is a system problem. It's nothing fancy. I send an email to my phone number within my logging class for alert levels. It works well enough, but it has one major flaw: A small hiccup in the system/site can turn into dozens of rapid fire text messages. Sometimes non-stop text messages until I log into the system and fix the problem. So I'm looking for pointers on software or services I can use that deal with alerts in a smarter way. Perhaps something that only sends me alerts X number of times within Y number of minutes. I'm not looking for a full monitoring suite. We already deal with that in house. I'm only looking to tackle this single problem.

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  • Citrix Secure Gateway not redirecting to login URL

    - by Dave
    We have an older setup for XenApp - users log in through Citrix Secure Gateway running on a windows box. (We hope to start using a NetScaler soon.) Earlier today, connections to https://citrix.company.com/ starting throwing up a 503 error page, instead of redirecting to https://citrix.company.com/Citrix/XenApp/ If you go directly to the /Citrix/Xenapp/ URL, the user is properly directed to the login page, and can launch apps. We've restarted the service, and rebooted the server. We haven't yet tried uninstalling and reinstalling the software. Before we do this, I'm looking for ideas as to how we can get the redirect working again without a fairly major outage window. To make things more interesting, many of our users have Citrix Receiver installed, also pointed at https://citrix.company.com/. Receiver makes itself the default launcher for ICA files, and gives a connection error when it tries to load apps - probably because of the same non-functional rediect?

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  • OpenWorld 2012—Is Almost Here!

    - by Scott McNeil
    With OpenWorld fast approaching, I thought I would take this opportunity to look at some of the “must see” database manageability activities and sessions happening this year. Here's a quick run down: Oracle Database Manageability: Download all the details for sessions, hands-on-labs, and demos (PDF) Keynotes: Sunday, September 30 Hardware and Software, Engineered to Work Together: Why It’s A Different Approach Larry Ellison, CEO, Oracle Monday, October 1 Shift Complexity Hosted by Mark Hurd, President, Oracle Andrew Mendelsohn, Senior Vice President, Database Server Technologies, Oracle IOUG SIG Sunday: Database Performance Tuning: Getting the Best out of Oracle Enterprise Manager Cloud Control 12c (session ID# CON6511) Oracle DEMOgrounds: Floor plan – Moscone South Automatic Application and SQL Tuning Automatic Performance Diagnostics Complete Database Lifecycle Management Data Masking and Data Subsetting Database Testing with Oracle Real Application Testing Oracle Enterprise Manager Cloud Control 12c Overview Oracle Exadata Management Hands-on-Labs: Database Performance Testing, Data Masking, and Subsetting (session ID# HOL10720) Database Performance Tuning Hands-on Lab (session ID# HOL10393) Sessions: What’s Next for Oracle Database? (session ID# GEN8259) Building and Managing a Private Oracle Database Cloud (session ID# GEN11421) Using Oracle Enterprise Manager to Manage Your Own Private Cloud (session ID# GEN11423) Extreme Database Management with the Latest Generation of Database Technology (session ID# CON9547) Oracle OpenWorld Music Festival New this year is Oracle’s first annual Oracle OpenWorld Musical Festival, featuring some of today's breakthrough musicians from around the country and the world. It's five nights of back-to-back performances in the heart of San Francisco—free to registered attendees. See the lineup Not Heading to OpenWorld—Watch it Live! Stay Connected: Twitter | Facebook | YouTube | Linkedin | Newsletter Download the Oracle Enterprise Manager Cloud Control12c Mobile app

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  • Is there an alternative to Google Code Search?

    - by blunders
    Per the Official Google Blog: Code Search, which was designed to help people search for open source code all over the web, will be shut down along with the Code Search API on January 15, 2012. Google Code Search is now gone, and since that makes it much harder to understand the features it presented, here's my attempt to render them via information I gathered from a cache of the page for the Search Options: The "In Search Box" just notes the syntax to type the command directly in the main search box instead of using the advance search interface. Package (In Search Box: "package:linux-2.6") Language (In Search Box: "lang:c++") (OPTIONS: any language, actionscript, ada, applescript, asp, assembly, autoconf, automake, awk, basic, bat, c, c#, c++, caja, cobol, coldfusion, configure, css, d, eiffel, erlang, fortran, go, haskell, inform, java, java, javascript, jsp, lex, limbo, lisp, lolcode, lua, m4, makefile, maple, mathematica, matlab, messagecatalog, modula2, modula3, objectivec, ocaml, pascal, perl, php, pod, prolog, proto, python, python, r, rebol, ruby, sas, scheme, scilab, sgml, shell, smalltalk, sml, sql, svg, tcl, tex, texinfo, troff, verilog, vhdl, vim, xslt, xul, yacc) File (In Search Box: "file:^.*.java$") Class (In Search Box: "class:HashMap") Function (In Search Box: "function:toString") License (In Search Box: "license:mozilla") (OPTIONS: null/any-license, aladdin/Aladdin-Public-License, artistic/Artistic-License, apache/Apache-License, apple/Apple-Public-Source-License, bsd/BSD-License, cpl/Common-Public-License, epl/Eclipse-Public-License, agpl/GNU-Affero-General-Public-License, gpl/GNU-General-Public-License, lgpl/GNU-Lesser-General-Public-License, disclaimer/Historical-Permission-Notice-and-Disclaimer, ibm/IBM-Public-License, lucent/Lucent-Public-License, mit/MIT-License, mozilla/Mozilla-Public-License, nasa/NASA-Open-Source-Agreement, python/Python-Software-Foundation-License, qpl/Q-Public-License, sleepycat/Sleepycat-License, zope/Zope-Public-License) Case Sensitive (In Search Box: "case:no") (OPTIONS: yes, no) Also of use in understanding the search tool would be the still live FAQs page for Google Code Search. Is there any code search engine that would fully replace Google Code Search's features?

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  • cloning mac address of physical server converted into vmware server

    - by user24981
    We've recently converted a physical Windows Server 2003 into vmware using P2V. However, one of the pieces of software on the 2003 machine are still looking for the old server's network MAC address in order to run. I've read several articles where it's discussed that you can modify the last part of the generated address and set it to static, but I need to clone the whole mac address to mimic the one in the old server. We're running CentOS and VMware server 2.0 as the host system. I was told that maybe adding in a second network card in the host and setting the virtual system's nic to that card instead of "bridged" would allow me to edit the vmx file and clone the whole MAC address. I can't use the old network card from the physical server because it's ISA and our new bus is PCI Any ideas? Thanks, Mike

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  • DBan not working because disk has bad sectors? [migrated]

    - by canadiancreed
    Attempting to wipe the drive of a laptop that I have before it's sold, and normally use DBAN to do so. However this time it starts and then finishes instantly with the following message. "DBAN finished with non-fatal errors This is usually cause by disks with bad sectors" Have tried multiple flags such as noverify to force it to skip this check (it doesn't show bad sectors in the OS scan in windows). but the error always comes back. This is the only time that I've seen this message, as every other of the few drives I've used this software on usually take 3-5 hours to do their job.

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  • Why does 1080p through a VGA cable fit my HDTV but is oversized when through an HDMI cable?

    - by GraemeF
    I have put together a new PC with a XFX GeForce GTX 260 graphics card and have it connected to my HDTV. First, I used an old VGA cable with a DVI to VGA adapter and plugged it in to my HDTV's VGA port. Running at 1920x1080 it fit the screen perfectly. Now, to avoid running another cable across the room, I have connected it with a DVI to HDMI cable to my TV's HDMI port, and the desktop at 1920x1080 is cropped by the edge of the screen. I have "fixed" the cropping by using NVIDIA's "Adjust desktop size and position" tool, which created a screen resolution of 1814x1022 to fit the screen, but this is no longer the TV's native resolution and confuses some software (e.g. WoW). Why does VGA work as expected, but HDMI is scaled up? Can it be avoided?

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  • UEC - Can the Cluster Controller and Storage Controller be seperate systems?

    - by Jeremy Hajek
    My department is implementing an Ubuntu Enterprise Cloud. I have done the testing and am quite comfortable with the 4 pieces, CC/SC, CLC, WS, NC. Looking at various documents below it appears the the Storage Controller and Cluster Controller (eucalyptus-sc and eucalyptus-cc) are always installed on the same system. My question is this: can I install the storage controller and the cluster controller on separate systems? http://open.eucalyptus.com/wiki/EucalyptusAdvanced_v2.0 the picture indicates that cc and sc are two different machines http://www.canonical.com/sites/default/files/active/Whitepaper-UbuntuEnterpriseCloudArchitecture-v1.pdf P.10 1st paragraph uses the word "machine(s)" http://software.intel.com/file/31966 P. 8 indicates the same separate architecture BUT... https://help.ubuntu.com/community/UEC/PackageInstallSeparate indicates below that the SC and CC are to be on the same system.

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  • How does a PDF prevent itself from being printed?

    - by Steven
    I have a PDF for my camera's manual, and Adobe Reader won't let me print it (the print option is grayed out). SumatraPDF also does the same thing (it even says print denied). How does the PDF prevent itself from being printed? It seems that if the program can display it on the screen, then it can also print it. Maybe Adobe Reader respects the PDF not printing, but surely an open source PDF reader wouldn't be so restrictive. So is there something more to this than merely the PDF reader software respecting the PDF's request to not be able to be printed?

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  • Set mouse or keyboard button to simulate left click and hold or rapid left click repeating in Windows?

    - by miahelf
    Does anyone know a way to configure Windows 7 or use third party software to do this? I would like to click my middle mouse button and have it tell Windows to left click and hold until I click the middle mouse button again. A keyboard key would be fine as well. Some games and apps have me holding down the left mouse button for a long time and I would like to reduce the stress on my mouse hand. Also, I would like to do a similar thing but have it repeatedly click the left mouse button automatically if possible. If none of that is possible, how about temporalily setting a keyboard key to achieve a left mouse button emulation?

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  • Organizations &amp; Architecture UNISA Studies &ndash; Chap 7

    - by MarkPearl
    Learning Outcomes Name different device categories Discuss the functions and structure of I/.O modules Describe the principles of Programmed I/O Describe the principles of Interrupt-driven I/O Describe the principles of DMA Discuss the evolution characteristic of I/O channels Describe different types of I/O interface Explain the principles of point-to-point and multipoint configurations Discuss the way in which a FireWire serial bus functions Discuss the principles of InfiniBand architecture External Devices An external device attaches to the computer by a link to an I/O module. The link is used to exchange control, status, and data between the I/O module and the external device. External devices can be classified into 3 categories… Human readable – e.g. video display Machine readable – e.g. magnetic disk Communications – e.g. wifi card I/O Modules An I/O module has two major functions… Interface to the processor and memory via the system bus or central switch Interface to one or more peripheral devices by tailored data links Module Functions The major functions or requirements for an I/O module fall into the following categories… Control and timing Processor communication Device communication Data buffering Error detection I/O function includes a control and timing requirement, to coordinate the flow of traffic between internal resources and external devices. Processor communication involves the following… Command decoding Data Status reporting Address recognition The I/O device must be able to perform device communication. This communication involves commands, status information, and data. An essential task of an I/O module is data buffering due to the relative slow speeds of most external devices. An I/O module is often responsible for error detection and for subsequently reporting errors to the processor. I/O Module Structure An I/O module functions to allow the processor to view a wide range of devices in a simple minded way. The I/O module may hide the details of timing, formats, and the electro mechanics of an external device so that the processor can function in terms of simple reads and write commands. An I/O channel/processor is an I/O module that takes on most of the detailed processing burden, presenting a high-level interface to the processor. There are 3 techniques are possible for I/O operations Programmed I/O Interrupt[t I/O DMA Access Programmed I/O When a processor is executing a program and encounters an instruction relating to I/O it executes that instruction by issuing a command to the appropriate I/O module. With programmed I/O, the I/O module will perform the requested action and then set the appropriate bits in the I/O status register. The I/O module takes no further actions to alert the processor. I/O Commands To execute an I/O related instruction, the processor issues an address, specifying the particular I/O module and external device, and an I/O command. There are four types of I/O commands that an I/O module may receive when it is addressed by a processor… Control – used to activate a peripheral and tell it what to do Test – Used to test various status conditions associated with an I/O module and its peripherals Read – Causes the I/O module to obtain an item of data from the peripheral and place it in an internal buffer Write – Causes the I/O module to take an item of data form the data bus and subsequently transmit that data item to the peripheral The main disadvantage of this technique is it is a time consuming process that keeps the processor busy needlessly I/O Instructions With programmed I/O there is a close correspondence between the I/O related instructions that the processor fetches from memory and the I/O commands that the processor issues to an I/O module to execute the instructions. Typically there will be many I/O devices connected through I/O modules to the system – each device is given a unique identifier or address – when the processor issues an I/O command, the command contains the address of the address of the desired device, thus each I/O module must interpret the address lines to determine if the command is for itself. When the processor, main memory and I/O share a common bus, two modes of addressing are possible… Memory mapped I/O Isolated I/O (for a detailed explanation read page 245 of book) The advantage of memory mapped I/O over isolated I/O is that it has a large repertoire of instructions that can be used, allowing more efficient programming. The disadvantage of memory mapped I/O over isolated I/O is that valuable memory address space is sued up. Interrupts driven I/O Interrupt driven I/O works as follows… The processor issues an I/O command to a module and then goes on to do some other useful work The I/O module will then interrupts the processor to request service when is is ready to exchange data with the processor The processor then executes the data transfer and then resumes its former processing Interrupt Processing The occurrence of an interrupt triggers a number of events, both in the processor hardware and in software. When an I/O device completes an I/O operations the following sequence of hardware events occurs… The device issues an interrupt signal to the processor The processor finishes execution of the current instruction before responding to the interrupt The processor tests for an interrupt – determines that there is one – and sends an acknowledgement signal to the device that issues the interrupt. The acknowledgement allows the device to remove its interrupt signal The processor now needs to prepare to transfer control to the interrupt routine. To begin, it needs to save information needed to resume the current program at the point of interrupt. The minimum information required is the status of the processor and the location of the next instruction to be executed. The processor now loads the program counter with the entry location of the interrupt-handling program that will respond to this interrupt. It also saves the values of the process registers because the Interrupt operation may modify these The interrupt handler processes the interrupt – this includes examination of status information relating to the I/O operation or other event that caused an interrupt When interrupt processing is complete, the saved register values are retrieved from the stack and restored to the registers Finally, the PSW and program counter values from the stack are restored. Design Issues Two design issues arise in implementing interrupt I/O Because there will be multiple I/O modules, how does the processor determine which device issued the interrupt? If multiple interrupts have occurred, how does the processor decide which one to process? Addressing device recognition, 4 general categories of techniques are in common use… Multiple interrupt lines Software poll Daisy chain Bus arbitration For a detailed explanation of these approaches read page 250 of the textbook. Interrupt driven I/O while more efficient than simple programmed I/O still requires the active intervention of the processor to transfer data between memory and an I/O module, and any data transfer must traverse a path through the processor. Thus is suffers from two inherent drawbacks… The I/O transfer rate is limited by the speed with which the processor can test and service a device The processor is tied up in managing an I/O transfer; a number of instructions must be executed for each I/O transfer Direct Memory Access When large volumes of data are to be moved, an efficient technique is direct memory access (DMA) DMA Function DMA involves an additional module on the system bus. The DMA module is capable of mimicking the processor and taking over control of the system from the processor. It needs to do this to transfer data to and from memory over the system bus. DMA must the bus only when the processor does not need it, or it must force the processor to suspend operation temporarily (most common – referred to as cycle stealing). When the processor wishes to read or write a block of data, it issues a command to the DMA module by sending to the DMA module the following information… Whether a read or write is requested using the read or write control line between the processor and the DMA module The address of the I/O device involved, communicated on the data lines The starting location in memory to read from or write to, communicated on the data lines and stored by the DMA module in its address register The number of words to be read or written, communicated via the data lines and stored in the data count register The processor then continues with other work, it delegates the I/O operation to the DMA module which transfers the entire block of data, one word at a time, directly to or from memory without going through the processor. When the transfer is complete, the DMA module sends an interrupt signal to the processor, this the processor is involved only at the beginning and end of the transfer. I/O Channels and Processors Characteristics of I/O Channels As one proceeds along the evolutionary path, more and more of the I/O function is performed without CPU involvement. The I/O channel represents an extension of the DMA concept. An I/O channel ahs the ability to execute I/O instructions, which gives it complete control over I/O operations. In a computer system with such devices, the CPU does not execute I/O instructions – such instructions are stored in main memory to be executed by a special purpose processor in the I/O channel itself. Two types of I/O channels are common A selector channel controls multiple high-speed devices. A multiplexor channel can handle I/O with multiple characters as fast as possible to multiple devices. The external interface: FireWire and InfiniBand Types of Interfaces One major characteristic of the interface is whether it is serial or parallel parallel interface – there are multiple lines connecting the I/O module and the peripheral, and multiple bits are transferred simultaneously serial interface – there is only one line used to transmit data, and bits must be transmitted one at a time With new generation serial interfaces, parallel interfaces are becoming less common. In either case, the I/O module must engage in a dialogue with the peripheral. In general terms the dialog may look as follows… The I/O module sends a control signal requesting permission to send data The peripheral acknowledges the request The I/O module transfers data The peripheral acknowledges receipt of data For a detailed explanation of FireWire and InfiniBand technology read page 264 – 270 of the textbook

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  • RAID1 Hard drives with Intel Controller

    - by Dave_H
    I have an older server with 2 35GB hard drives arranged as a RAID-1 drive. I have 3 open bays, I'd like to add 2 more hard drives to the open bays and have all 4 drives configured as a RAID-1 drive that Windows sees as 1 larger drive. Is this possible? If not, the new drives are 2x as big as the old drives, is it possible to replace 1 of the old drives and rebuild then replace the second drive and rebuild and somehow expand the array to use all of the available space? The server is using an Intel hardware raid controller, the software interface is Intel Storage Console v2.12.

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