Saturday, November 16, 2013

Stresslinux – Torture Tests to Your Hardware

Stresslinux Torture-Tests Your Hardware

Stresslinux is a lean, mean torture machine with 750MB of hardware-pummeling goodness for probing and load-testing your computer's hardware. Why, you ask, would anyone want to torture their nice hardware? Perhaps "torture" isn't the best word; think load-testing to expose defects, "burning in" a new machine, or to figure out some limits for overclocking.

Stresslinux runs from external bootable media: CD, USB stick, PXE boot, or you can run the VMWare image. My favorite is a USB stick because it is fast. There are good instructions for creating your chosen boot medium.

When you boot up, you have the option to allow sl-wizard to probe your system for sensors and then load the appropriate drivers (see the screen shot, below).

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Probing system sensors at boot.

You can re-run this anytime after boot by deleting /tmp/sensors and then running the sl-wizard.sh script as root, like this:

Exploring Stresslinux

This is not your ordinary stripped-down Linux. It was built with SUSE Studio, and is based on OpenSUSE. If you like playing with test builds there are a ton of 'em.

Stresslinux uses Busybox in place of the usual coreutils, fileutils, and other standard Linux commands. Busybox is a single stripped-down binary containing several dozen commands, and it uses the ash shell, so you may find that some of your favorite options are missing. The Busybox command reference should help you.

Stresslinux uses the Fn keys in an interesting way. There are 6 ordinary ttys on F1-F6, and it boots to tty1 on F1. The rest are normal login ttys. On US keyboards you can switch between these with ALT+Fn. (STRG+Fn on German keyboards, which is the same as CTRL+Fn.) F10 displays eth0 throughput (see above), F11 shows hard disk temperatures, and F12 displays lm-sensors readings.

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Probing system sensors at boot.

That Was Fun, Now What?

Now that Stresslinux is booted up and you have gazed upon your eth0 and sensor outputs, what's next? Let's spend some time with the stress command, because that is a good general-purpose workload generator. It operates by siccing a bunch of hogs on your system. This simple invocation puts a light load on the CPU, I/O, memory, and hard drive:

  • > stress --cpu 8 --io 4 --vm 2 --hdd 4 --timeout 30s --verbose
  • stress: info: [16275] dispatching hogs: 8 cpu, 4 io, 2 vm, 4 hdd
  • stress: dbug: [16275] using backoff sleep of 54000us
  • stress: dbug: [16275] setting timeout to 10s
  • stress: dbug: [16275] --> hogcpu worker 8 [16276] forked
  • stress: dbug: [16275] --> hogio worker 4 [16277] forked
  • stress: dbug: [16275] --> hogvm worker 2 [16278] forked
  • stress: dbug: [16275] --> hoghdd worker 4 [16279] forked
  • stress: dbug: [16275] using backoff sleep of 42000us
  • stress: dbug: [16275] setting timeout to 10s
  • [...]
  • stress: info: [16275] successful run completed in 13s

That snippet shows I wasn't kidding about the hogs. When it finishes with "successful run completed" that means there were no errors. If it did detect errors, it would either try to tell you what they were, or tell you to examine the syslog. Let's walk through this so we know what it's doing.

--cpu 8 tells it to fork 8 processes. Each process calculates the square root of a random number (by calling the sqrt() and rand functions) in a loop that stops at the end of your timeout, or when you stop it with CTRL+c. Are there any geezers out there who remember who said "Computer. Compute to the last digit the value of pi?" And why? This is similar, a way to keep the CPU constantly busy.

--io 4 forks 4 processes that call the sync() function in a loop. sync() flushes any data buffered in memory to disk. Most Linux filesystems use delayed allocation; that is, data are held in memory for a period of time before being written to disk. This speeds up performance because disk I/O is slower than RAM. Running this one by itself and trying out different values will give you an idea of your I/O performance.

--vm 2 thrashes your RAM by forking 2 processes to allocate and release memory. (Looping malloc() and free().)

--hdd 4 pummels your hard drive with writes, by calling the write function in a loop.

--timeout 30s tells stress to stop after 30 seconds. Or whatever time you want, of course, using s,m,h,d,y (seconds, minutes, hours, days, years). Always set a timeout, because this is your protection from the system locking up and becoming inaccessible. stress runs in userspace and can't cause any damage, but it would be sad to have to reboot to stop it.

--verbose makes it spit out many lines telling what it is doing.

The example above is pretty wimpy and won't stress out anything made after 1990. You can run one test at a time, for example. This puts a much larger load on your CPU:

> stress --cpu 2000 --timeout 30s --verbose

Just for fun, follow along with top, and press 1 to see all cores individually:

  • top - 18:58:17 up 8:56, 9 users, load average: 419.86, 226.40, 88.02
  • Tasks: 2207 total, 1449 running, 756 sleeping, 0 stopped, 2 zombie
  • Cpu0 :100.0%us, 0.0%sy, 0.0%ni, 0.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
  • Cpu1 : 98.1%us, 1.6%sy, 0.0%ni, 0.0%id, 0.0%wa, 0.0%hi, 0.3%si, 0.0%st
  • Cpu2 : 97.7%us, 2.3%sy, 0.0%ni, 0.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
  • When your stress run is finished, notice the difference in the Tasks statistics and load averages.

You can control the load on your memory with the --vm-bytes option. Suppose you have 8GB memory, which is not unusual in these here modern times. Try this:

> stress --vm 2 --vm-bytes 6G --timeout 30s --verbose

Be careful with this because thrashing your memory can make your system hang. The vm option allocates and releases memory; the vm-hang simulates low memory conditions by having each hog process go to sleep, rather than releasing memory. This example hogs 3 gigabytes of memory:

> stress --vm 2 --vm-bytes 3G --vm-hang --timeout 60s

What happens when your system is I/O bound? Try this:

> stress --io 8 --timeout 2m

Test your hard drive by writing a large file to disk:

> stress --hdd 1 --timeout 5m

The default file size is 1GB, and you can specify any size with the --hdd-bytes option, for example --hdd-bytes 5G writes a 5 gigabyte file.

stress is tidy and cleans up after itself, so you shouldn't have to worry about leftover hogs running amok. The documentation on stress isn't exactly lavish, and the most complete help is in info stress.

Other Commands

Visit the Stresslinux software page to see all of its system-testing commands. It includes reliable standbys like CPU burn, memtest, bonnie++, lshw (list system hardware, my fave), tiobench, and smartmontools. There are a lot of nice Linux bootable system rescue distros that do this and that and everything, but I think Stresslinux is tops for a good specialized distro.

Taken From: https://www.linux.com/learn/tutorials/613523:stresslinux-torture-tests-your-hardware

Thursday, November 14, 2013

Serial Port (RS232) - Null Modem / Straight Through

The Difference Between a Null Modem and Straight Through Serial Cable

Hardware: Serial

Problem:
I would like to use my computer's built-in serial port to communicate with a serial device, and I have both the null modem and straight through serial cables. What is the difference between the two cables, and which one should I use?

Solution:
The null modem cable is frequently called a crossover cable. It is used to allow two serial Data Terminal Equipment (DTE) devices to communicate with each other without using a modem or a Data Communications Equipment (DCE) device in between. For this to happen, the Transmit (TXD) pin of one device needs to be connected to the Receive (RXD) pin of the other device.  To enable handshaking between the two devices, the Request to Send (RTS) pin of one device must be connected to the Clear to Send (CTS) pin of the other device. Because these pins are "crossed" on the two cable terminals, the name crossover cable is used.

Simple Null Modem Cable

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Null Modem Cable with Handshaking

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A straight-through cable is used to connect a DTE device to a DCE device. The TXD-RXD and RTS-CTS pins are not cross-connected in this case, hence the term straight through cable.

Simple Straight Through Cable

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The built-in serial port on a PC is a DTE device. Modems and printers are examples of DCE devices.  Note that an instrument with serial interface could be either a DTE or a DCE device.  It is best to check the user manual of the instrument to find out the device type.  For more information regarding DTE and DCE devices, please see the links below.
To tell if your cable is null modem or straight though, you can search the part number at ni.com, the product description will tell if it is null modem. Alternatively you can use a hand held DMM to test continuity on the individual pins of your serial cable. If every pin is electrically connected to the corresponding pin on the other end, i.e.: pin 1 to pin1, pin 2 to pin 2, etc. then the cable is straight through.


Related Links:
Products and Services: Serial Interfaces
KnowledgeBase 1TU953QR: What Do DTE and DCE Mean in Serial Communication?
Developer Zone Tutorial: Serial Communication General Concept

Attachments:

Report Date: 22/12/2004
Last Updated: 18/06/2010
Document ID: 3GLDMSIT

Taken From: http://digital.ni.com/public.nsf/allkb/1EE0DD8AF67922FA86256F720071DECF

Sunday, November 10, 2013

Make Your own PoE - Injector and Splitter

Make your own Power Over Ethernet Injector set for $2 in Parts

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Ever need to install a network hub, camera, or other device in a location that did not have a locally available power outlet? Need to ‘extend’ the power cord?

In this tutorial, we’ll be building a very cheap Power Over Ethernet Injector out of $2 in parts. This will let you place your power supply for your device near the ethernet hub, where power is plentiful, and place the device itself hundreds of feet away.

Caveat: There is a Power Over Ethernet (POE) standard, which we’re ignoring, as this particular injector setup is for legacy products that do not offer POE support.

The standart states the minumum power supply should be:

  • 44V DC / 350mA = 15.4 Watts

so for standart compatibility (802.3af - PSE Mid-Span) you would have to use a 48V DC power supply with equal or more than 350mA.

In my case, I’m making it for my wired network camera, a Hawking HNC-210, which is generally alwayssituated farther away from the power outlet. It comes with a fairly short (6′) power cable, which is an odd product design consideration. Since you’d generally put a camera at eye-level or higher, this cable is really too short for most installs.

Parts List: $1.80 US:

  • 1. RJ-45 pass-thru connector 80¢
  • 2. 2.1mm power jack and plug 50¢
  • 3. spare (short) working ethernet cable 50¢

The first item we need is an ethernet (RJ-45) pass-thru connector, for patching 2 ethernet cables end to end. It is available at many local retailers/computer shops. I grabbed a few at BG Micro for 80¢ a piece. The nice thing about these is you’re getting 2 pre-wired RJ-45 connectors for very cheap.

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A bit of man-handling to pry the two halves apart, and we have 2 halves of our POE injector. Simply cut all 8 wires at the half way point. You can tell which wire goes to which pin by looking at the inside of the now disassembled connector. Take notes of which wire goes to which pin, using a regular ethernet cable as a reference. There are 8 wires, which we need to be grouped. 4 wires are for ethernet, 2 wires for Positive Power, and 2 wires for Negative Power (Ground).

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You’ll need to strip and tin all the ends of each tiny wire on both pieces. We’re basically hand-wiring connections for power and ethernet in each connector. Use the wiring table later in this article to make the connections. While you’re here, why not put some shrink tubing over each wire to protect them from cross-connection later.

I need more Power, Scotty!

Next up in the arsenal, we need the power jacks to pass the power from the AC wall wart to the camera. I checked the camera, and it used a standard 2.1mm power jack. I picked up 2 example jacks from an electronics supplier.

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The top set is an inline jack and plug, which costs $1.20 for the set. The bottom set is an panel mount jack and plug, which costs considerably less, at only 50¢ for the set. First, check to make sure they work together.

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I soldered 2 wires to the power plug that were equal length to the ethernet dongle I already had on hand. I slipped some shrink tubing over it, then made the connections.

With the Power Connections, polarity doesn’t matter as much as making sure you don’t flip the circuit with your cable build. If you decide blue is tip and brown is ground, stick with it at both ends of the injectors – not following this is a sure way of destroying the device you’re powering.

In my case, I connected the tip of the power plug to BOTH the 2 blue wires, and the shield to BOTH the 2 brown wires. On the other side, I connected the same to the tiny panel-mount power jack. I then used hot-melt glue to mount the panel mount to the remaining plastic frame.

Why connect to both wires? In case one wire fails in a regular ethernet cable, it’ll still work. Plus, there is less voltage loss with the larger combined wire. The total voltage loss is negligible for most installs. If you find your device isn’t working properly, check to see if the cable is too long, and the voltage is too low to power the device.

Next up the complex ethernet wiring….

Common straight-through ethernet cables only use 4 wires out of the 8 inside the sheathing. The common wiring in illustrated below.

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Take your short working ethernet cord and cut it in half. You’ll want 2 short 8″ pieces, with the working ethernet RJ-45 ends still attached. Strip off an inch at the cut end, and expose the 8 wires inside. Cut the blue and brown sets of wires off. These are unused in this application – these ‘dongles’ will be the ethernet in and out connections.

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So the ethernet wires (in most cases, you should check) that we’ll be using to pass the ethernet traffic is the 2 orange wires and the 2 green wires, which fall on pins 1, 2, 3 and 6. Simply connect the pin 1 on the ethernet dongle to pin 1 on the ethernet connector jack, and so on through the other 7 wires on both sides.

Finished Power Over Ethernet Injector and Splitter

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I covered open connections with shrink tubing, then tucked all wires inside the tiny connector cases. I then used hot-melt glue to seal up the open ends of the connectors, and now I have a matched pair of Power Over Ethernet Injectors!

Installed at the Camera End

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Simply attach one end of your 100+ foot long ethernet cable to this end, place your camera anywhere, with only one cable feeding to it.

Installed at Hub/Switch End

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At the other end, at the switch/hub (also suitably close to a power outlet), simply plug it into an available port, plug in the power supply, then the camera feed line.

Shield your eyes! Cable Porn! Shocking double-69 cable-on-cable action!

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Based On: http://underdesign.wordpress.com/2010/04/07/make-your-own-power-over-ethernet-injector/

PoE Standart Details: http://www.ieee.li/pdf/viewgraphs/introduction_to_poe_ieee802.3af_802.3at.pdf

Monday, November 4, 2013

Linux Swap Space – All You Need to Know

All about Linux swap space

By Gary Sims

Linux divides its physical RAM (random access memory) into chucks of memory called pages. Swapping is the process whereby a page of memory is copied to the preconfigured space on the hard disk, called swap space, to free up that page of memory. The combined sizes of the physical memory and the swap space is the amount of virtual memory available.

Swapping is necessary for two important reasons. First, when the system requires more memory than is physically available, the kernel swaps out less used pages and gives memory to the current application (process) that needs the memory immediately. Second, a significant number of the pages used by an application during its startup phase may only be used for initialization and then never used again. The system can swap out those pages and free the memory for other applications or even for the disk cache.

However, swapping does have a downside. Compared to memory, disks are very slow. Memory speeds can be measured in nanoseconds, while disks are measured in milliseconds, so accessing the disk can be tens of thousands times slower than accessing physical memory. The more swapping that occurs, the slower your system will be. Sometimes excessive swapping or thrashing occurs where a page is swapped out and then very soon swapped in and then swapped out again and so on. In such situations the system is struggling to find free memory and keep applications running at the same time. In this case only adding more RAM will help.

Linux has two forms of swap space: the swap partition and the swap file. The swap partition is an independent section of the hard disk used solely for swapping; no other files can reside there. The swap file is a special file in the filesystem that resides amongst your system and data files.

To see what swap space you have, use the command swapon -s. The output will look something like this:

Filename Type Size Used Priority

/dev/sda5 partition 859436 0 -1

Each line lists a separate swap space being used by the system. Here, the 'Type' field indicates that this swap space is a partition rather than a file, and from 'Filename' we see that it is on the disk sda5. The 'Size' is listed in kilobytes, and the 'Used' field tells us how many kilobytes of swap space has been used (in this case none). 'Priority' tells Linux which swap space to use first. One great thing about the Linux swapping subsystem is that if you mount two (or more) swap spaces (preferably on two different devices) with the same priority, Linux will interleave its swapping activity between them, which can greatly increase swapping performance.

To add an extra swap partition to your system, you first need to prepare it. Step one is to ensure that the partition is marked as a swap partition and step two is to make the swap filesystem. To check that the partition is marked for swap, run as root:

fdisk -l /dev/hdb

Replace /dev/hdb with the device of the hard disk on your system with the swap partition on it. You should see output that looks like this:

Device Boot Start End Blocks Id System

/dev/hdb1 2328 2434 859446 82 Linux swap / Solaris

If the partition isn't marked as swap you will need to alter it by running fdisk and using the 't' menu option. Be careful when working with partitions -- you don't want to delete important partitions by mistake or change the id of your system partition to swap by mistake. All data on a swap partition will be lost, so double-check every change you make. Also note that Solaris uses the same ID as Linux swap space for its partitions, so be careful not to kill your Solaris partitions by mistake.

Once a partition is marked as swap, you need to prepare it using the mkswap (make swap) command as root:

mkswap /dev/hdb1

If you see no errors, your swap space is ready to use. To activate it immediately, type:

swapon /dev/hdb1

You can verify that it is being used by running swapon -s. To mount the swap space automatically at boot time, you must add an entry to the /etc/fstab file, which contains a list of filesystems and swap spaces that need to be mounted at boot up. The format of each line is:

Since swap space is a special type of filesystem, many of these parameters aren't applicable. For swap space, add:

/dev/hdb1 none swap sw 0 0

where /dev/hdb1 is the swap partition. It doesn't have a specific mount point, hence none. It is of type swapwith options of sw, and the last two parameters aren't used so they are entered as 0.

To check that your swap space is being automatically mounted without having to reboot, you can run the swapoff -a command (which turns off all swap spaces) and then swapon -a (which mounts all swap spaces listed in the /etc/fstab file) and then check it with swapon -s.

Swap file

As well as the swap partition, Linux also supports a swap file that you can create, prepare, and mount in a fashion similar to that of a swap partition. The advantage of swap files is that you don't need to find an empty partition or repartition a disk to add additional swap space.

To create a swap file, use the dd command to create an empty file. To create a 1GB file, type:

dd if=/dev/zero of=/swapfile bs=1024 count=1048576

/swapfile is the name of the swap file, and the count of 1048576 is the size in kilobytes (i.e. 1GB).

Prepare the swap file using mkswap just as you would a partition, but this time use the name of the swap file:

mkswap /swapfile

And similarly, mount it using the swapon command: swapon /swapfile.

The /etc/fstab entry for a swap file would look like this:

/swapfile none swap sw 0 0

How big should my swap space be?

It is possible to run a Linux system without a swap space, and the system will run well if you have a large amount of memory -- but if you run out of physical memory then the system will crash, as it has nothing else it can do, so it is advisable to have a swap space, especially since disk space is relatively cheap.

The key question is how much? Older versions of Unix-type operating systems (such as Sun OS and Ultrix) demanded a swap space of two to three times that of physical memory. Modern implementations (such as Linux) don't require that much, but they can use it if you configure it. A rule of thumb is as follows: 1) for a desktop system, use a swap space of double system memory, as it will allow you to run a large number of applications (many of which may will be idle and easily swapped), making more RAM available for the active applications; 2) for a server, have a smaller amount of swap available (say half of physical memory) so that you have some flexibility for swapping when needed, but monitor the amount of swap space used and upgrade your RAM if necessary; 3) for older desktop machines (with say only 128MB), use as much swap space as you can spare, even up to 1GB.

The Linux 2.6 kernel added a new kernel parameter called swappiness to let administrators tweak the way Linux swaps. It is a number from 0 to 100. In essence, higher values lead to more pages being swapped, and lower values lead to more applications being kept in memory, even if they are idle. Kernel maintainer Andrew Morton has said that he runs his desktop machines with a swappiness of 100, stating that "My point is that decreasing the tendency of the kernel to swap stuff out is wrong. You really don't want hundreds of megabytes of BloatyApp's untouched memory floating about in the machine. Get it out on the disk, use the memory for something useful."

One downside to Morton's idea is that if memory is swapped out too quickly then application response time drops, because when the application's window is clicked the system has to swap the application back into memory, which will make it feel slow.

The default value for swappiness is 60. You can alter it temporarily (until you next reboot) by typing as root:

echo 50 > /proc/sys/vm/swappiness

If you want to alter it permanently then you need to change the vm.swappiness parameter in the /etc/sysctl.conf file.

Conclusion

Managing swap space is an essential aspect of system administration. With good planning and proper use swapping can provide many benefits. Don't be afraid to experiment, and always monitor your system to ensure you are getting the results you need.

Taken From: http://www.linux.com/news/software/applications/8208-all-about-linux-swap-space

Thursday, October 31, 2013

How to Create a Windows 8 Portable (USB Stick)

 How to Create a Portable Version of Windows 8 Without Extra Software

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For a long time Linux users have been able to install their OS onto a portable USB drive, but Windows just caught up. Read on to find out how you can install Windows 8 onto a USB drive so you can take it wherever you go.

Note: This was written on the RTM version of Windows 8 Enterprise and you will need to have an RTM build of the Enterprise edition to complete the steps in this article.

Using Windows To Go to Create a Portable Workspace

Press the Win + X keyboard combination and select Control Panel from the context menu.

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You will need to change your Control Panel view to the Small Icons view.

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You should now see Windows To Go near the bottom of the Control Panel, click on it.

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You will now need to select the USB drive you would like to turn into a portable workspace, then click next.

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The wizard will automatically scan your CD\DVD and Removable drives for valid Windows installation files, once you have selected a version of Windows click next.

Note: If you store your installation files elsewhere you will need to add it as a search location.

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You can optionally set a BitLocker password, but we’ll pass on this option for now.

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Once you have reached the end of the wizard, you will be warned that your USB drive will be formatted. You can then click on create to kick of the creation process.

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That’s all there is to it, you now have a bootable USB with Windows on it.

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Note: Your portable USB will not show up in Explorer, this leaves us with a problem later on when you don’t need to use it as a Portable Workspace anymore.

How To Reformat Your Windows To Go USB Drive

If you’re done using Windows on a drive, you can reformat the drive, but you’ll need to open a command prompt and type diskpart, then press enter.

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Once you enter Diskpart you will need to find out which drive is the one you need to format, the list disk command will show you all the drive currently connected to your system. Take note of your drive number because we will need it in the next step.

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We now need to select the disk, you can simply use the select disk command along with your drive number from the previous step.

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Now that the disk is selected we can go ahead and wipe it.

Note: Clean is a ruthless command that will wipe all the file systems off your drive without any warnings, if you have selected the wrong drive previously this will result is a loss of data so make sure you have the right drive selected.

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We can now use the Win + R keyboard combination to bring up the run box  and open Disk Management.

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As soon as the Management console opens you will need to initialize the disk.

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Then you can go ahead and create your drives partition.

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That’s all there is to it.

Taken From: http://www.howtogeek.com/121322/how-to-create-a-portable-version-of-windows-8-without-extra-software/

How To Install JAVA on Debian (via Repository)

HOW TO INSTALL ORACLE JAVA 7 IN DEBIAN VIA REPOSITORY

A quick tip for Debian users who want to install and stay up to date with the latest Oracle Java 7 (JDK7): the WebUpd8 Java 7 PPA works on Debian too since the package is just an installer and all you have to do is manually add the PPA repository to the Software Sources.

As a reminder, the Oracle Java 7 PPA repository does not host any Java files but only an installer that automatically downloads and installs Oracle Java 7, like the flashplugin-installer package for instance.

To add the WebUpd8 Oracle Java PPA repository to the Software Sources in Debian (tested on Debian Squeeze, but it should work with any Debian version), use the following commands:

su -

echo "deb http://ppa.launchpad.net/webupd8team/java/ubuntu precise main" | tee -a /etc/apt/sources.list

echo "deb-src http://ppa.launchpad.net/webupd8team/java/ubuntu precise main" | tee -a /etc/apt/sources.list

apt-key adv --keyserver keyserver.ubuntu.com --recv-keys EEA14886

apt-get update

apt-get install oracle-java7-installer

exit

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And that's it, Oracle Java 7 (both JDK7 and JRE7) should now be installed and you should receive automatic updates with future Oracle Java 7 versions, under Debian.
Update: the current JDK version in the PPA is Oracle Java 7 Update 10 (7u10).

Setting Java environment variables

To automatically set up the Java 7 environment variables, you can install the following package:

sudo apt-get install oracle-java7-set-default

If you've already installed oracle-java6-set-default or oracle-java8-set-default, they will be automatically removed when installing oracle-java7-set-default (and the environment variables will be set for Oracle Java 7 instead).
For installing Oracle Java 7 in Ubuntu, see: Install Oracle Java 7 in Ubuntu via PPA Repository

Taken From: http://www.webupd8.org/2012/06/how-to-install-oracle-java-7-in-debian.html

Friday, October 18, 2013

Raspberry PI – BerryBoot Bootloader (Multi OS + USB)

BerryBoot v2.0 – bootloader

Universal Operating System Installer

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For people short on SD cards: Berryboot is a simple boot selection screen, allowing you to put multiple Linux distribution on a single SD card.

In addition it allows you to put the operating system files on an external USB hard drive instead of on the SD card itself.

Download link Berryboot for the Raspberry Pi: berryboot-20130908.zip

To install: extract the contents of the .zip file to a normal (FAT formatted) SD card, and put it in your Raspberry Pi. This can be simply done under Windows without any special image writer software.

Once you start your Pi it will start an installer that reformats the SD card and downloads the operating systems files from the Internet.

Other devices

In addition to running on the Raspberry Pi, Berryboot also supports Android tablets, TV sticks and boards that have an Allwinner A10 processor.
For more information see the BerryBoot A10 page

Changelog

→ Moved to: Berryboot Changelog

Walkthrough

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If your Pi is connected to the Internet BerryBoot will try to detect your location based on your IP-address, and set the right timezone automatically. Verify that it is correct and press “ok”

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Select where you want to store the operating system files, and press “format” You can install the operating system files on the SD card itself or an external USB stick/disk. Be aware that if you choose an external drive, the files of the operating system will be stored there, but you still need to keep the SD card in the Pi to boot from.

WARNING: all existing files on the disk will be erased.

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Select which operating system you want to install. You can add more later.

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It will download the files from the Internet automatically.

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In the Berryboot menu editor you can install more operating systems, rename them, delete them, etc. Press “exit” to exit the editor and start using the operating system you installed.

HDMI CEC support

When attached to a HDMI TV, you can also use the arrows on your TV remote to select an operating system to boot, instead of using your keyboard or mouse.

Available options in menu editor

§ “Add OS” (or CTRL+A on keyboard, red button on TV remote)
Single click to download additional operating systems from the Internet.
Hold down your mouse button over the “Add OS” button and select “copy OS from USB stick”, to install an operating system saved on USB stick.

§ “Edit” (or ENTER on keyboard)
Change the name of the selected operating system.
You used to be able to change the memory split setting here as well, but for new installations (that have CMA enabled) this is no longer used.

§ “Clone”
Creates a copy of the selected operating system.
It is possible to create either a copy that includes the file system changes you made, or create a copy of the original operating system image as downloaded from the Internet.

§ “Backup”
Creates a backup of a single operating system or all of them to a USB stick, or SD card (requires USB SD card reader).
Backups of individual images can be restored by holding down the “add OS” button and selecting “copy OS from USB stick”

§ “Delete” (or DEL on keyboard)
Deletes the files of the selected operating system.

§ “Make default”
Makes the selected operating system the default. On boot, this operating system will be started automatically unless another is selected within a number of seconds.

§ “Exit” (or ESC on keyboard)
Exits the menu editor.

Advanced options

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Click on the ”»” button to the right of the screen to see all options.

§ “Advanced configuration”
Editor for configuration files such as cmdline.txt and config.txt

When using a Raspberry Pi you can specify kernel parameters and Berryboot parameters in cmdline.txt (use uEnv.txt if you have another device).
Special Berryboot parameters:

bootmenutimeout=<number of seconds> - number of seconds before default operating system is started. nobootmenutimeout - do not start the default operating system automatically.

In config.txt advanced overscan, HDMI and overclocking settings can be specified. See the RPIconfig page on eLinux.org for details.
Note that overclocking is known to cause SD card filesystem corruption, so only use that when you are using an USB stick or drive as storage and know what you are doing.

§ “Console”
Activates a console on tty2
Press CTRL+ALT+F2 to access, username “root”, no password.

§ “Set password”
Password protects access to the menu editor, so that unauthorized users cannot delete or edit the operating systems.

§ “Repair filesystem”
Performs a file system check and repair. Attempts to repair file system corruption. Can perform a lot of writes to the SD card, so you might want to make a backup of important files first.

Alternative installation method using disk image

If you are experiencing problems unpacking the installation files to a FAT formatted SD card (the easiest and recommend installation method), you can alternatively use a tool like Win32diskimager or dd to write this disk image to the card.
The disk image is meant to install Berryboot on another device, but it includes the Raspberry Pi boot files as well.

More information

For advanced users:

§ Headless installation (install Berryboot without display attached, using VNC)

§ Adding your own custom operating systems to the menu

§ Berryboot source code on Github

§ Report bugs

Taken From: http://www.berryterminal.com/doku.php/berryboot