Samsung has filed for a Tablet/Slate patent that offers some interest. Essentially it offers dual touch screens on the front and back of a device. Apple filed for a similar patent awhile back. Does it have practical application? I’m not sure, but somebody must think so.

Forget everything you knew about mobile graphics – Nvidia’s Tegra 2 chip runs the Unreal Engine 3 with ease, delivers 3D performance of today’s high-end consoles, and enables days of battery life.

The Tegra 2 chip owes its processing performance to the use of ARM’s Cortex-A9 CPU, the latest and greatest in a series. Note that most smartphones run the Cortex-A8 chip, including Palm’s Pre, Apple’s iPhone 3GS, and Motorola’s Droid.

What blew us away was ARM’s recent performance video pitting a netbook with an Intel 1.6GHz Atom processor and a GPU versus a development board running only a 500MHz Cortex-A9 processor. The Cortex-A9 machine matched the Atom chip in browser rendering, even though it had no GPU and was clocked three times slower.

Graphics-wise, Tegra 2 delivers a huge bang for your buck. Epic Games’ CEO Tim Sweeny demoed the Unreal Engine 3 running on the Tegra 2 processor on stage at Nvidia’s press conference. Not only did the Tegra 2 system render the game with ease, but Sweeny proclaimed its 3D performance comparable to today’s high-end consoles. I’m sure a look at the demo, included here, will leave you speechless. Looks like 2010 will be the year of Tegra 2.

 

“It’s going to be the beginning of the tablet revolution,” Nvidia’s CEO Jen-Hsuan Huang told the media at the unveiling of the Tegra 2 platform (press release). Demoing a number of Tegra 2 tablet designs, Huang said the game-changing chip delivers 1080p video playback, ten times better performance than today’s smartphones, optimized Adobe Flash Player 10.1 rendering, and insane battery performance with up to 16 hours of HD video playback and 140 hours of music on a single charge.

 

Nvidia has sold the original Tegra chip to a few smaller vendors. If it weren’t for Microsoft and its Zune HD, the Tegra processor would have flopped. The company is now betting on the rise of tablets and portable computing devices unveiled at the CES, hoping to put the chip inside every gizmo with a screen size between five and ten inches. The category includes tablets like Apple’s iSlate (unless it opts for custom chips, as rumored), Google’s rumored Chrome OS-powered tablet, slates from HP and Dell – even next-gen handheld consoles like the follow-up to the Nintendo DS.

Even though Nvidia is facing tough competition in the mid and high segment from Intel’s Atom, performance and power metrics are on their side. Tegra 2 boasts full HD (1080p) video output and hardware-assisted rendering of processor-intensive content like Flash files without taxing your battery, making the chip a natural fit for portable entertainment devices that browse the web, like smartphones, tablets, and netbooks. Billed as “the world’s first dual-core, Cortex-A9 processor” Tegra 2 sports eight independent processor and is four times faster than its predecessor. All said, Tegra 2’s processing and graphics performance usher in a new era in mobile computing where upcoming devices will handle heavy-duty web browsing, HD video encoding and decoding, and mobile gaming with ease.

rsync is one of the tools that have gradually infiltrated my day to day tool-box (aside Vim and Zsh).

Using rsync it%u2019s very easy to mimic Mac OS X new feature called Time Machine. In this article I%u2019ll show how to do it, but there is still a nice GUI missing %u2013 for those who like it shiny.

What Time Machine does

Time Machine makes a snapshot of your files every hour. The files are usually stored on a external hard drive connected to your Mac via USB or Firewire. Earlier Leopard versions (ADC preview versions) had the ability to make the backups to a remote drive (I%u2019ve heard).

So if you lose a file, or did a devastating change to one of your files, simply go back in time until you find your file or a version that%u2019s not corrupted.

Incrementally backing up all files every hour so that you can access them in reversed chronological order isn%u2019t that hard with standard Unix utilities like rsync. The only missing thing is a nice GUI for which Apple is known to be quite good at.

Making full backups in no time every hour

You can use this method to make a backup every hour or every ten minutes if you like. There are many many features you can tune or configure to your own taste %u2013 excluding files that are larger than 1GB for example.

So, here the command to make the backup:

rsync -aP --link-dest=PATHTO/$PREVIOUSBACKUP $SOURCE $CURRENTBACKUP

Lets go through the parameters step by step.

• -a means Archive and includes a bunch of parameters to recurse directories, copy symlinks as symlinks, preserve permissions, preserve modification times, preserve group, preserve owner, and preserve device files. You usually want that option for all your backups.
• -P allows rsync to continue interrupted transfers and show a progress status for each file. This isn%u2019t really necessary but I like it.
• --link-dest this is a neat way to make full backups of your computers without losing much space. rsync links unchanged files to the previous backup (using hard-links, see below if you don%u2019t know hard-links) and only claims space for changed files. This only works if you have a backup at hand, otherwise you have to make at least one backup beforehand.
• PATHTO/$PREVIOUSBACKUP is the path to the previous backup for linking. Note: if you delete this directory, no other backup is harmed because rsync uses hard-links and the operating system (or filesystem) takes care of releasing space if no link points to that region anymore.
• $SOURCE is the directory you%u2019d like to backup.
• $CURRENTBACKUP is the directory to which you%u2019d like to make the backup. This should be a non-existing directory.

As said earlier, rsync has many many features. To exclude files over a certain size for example, use the option --max-size (unfortunately this is not available on the rsync version shipped with Mac OS X Leopard). The man page or the documentation can give you plenty of ideas in this direction.

So much for the theory of the most important command for our purpose. Here a simple script that makes an incremental backup every time you call it:

#!/bin/sh

date=`date " %Y-%m-%dT%H:%M:%S"`
rsync -aP --link-dest=$HOME/Backups/current /path/to/important_files $HOME/Backups/back-$date
rm -f $HOME/Backups/current
ln -s back-$date $HOME/Backups/current

The script creates a file called %u201Cback%u201D appended by the current date and time, for example back-2007-11-13T22:03:32 which contains the full backup. Then there is a symbolic link called %u201Ccurrent%u201D which points to the most recent directory. This directory-link is used for the --link-dest parameter.

You should look at the --exclude parameter (or better, --exclude-from= parameter) and learn how to exclude certain files or directories from the backup (you shouldn%u2019t backup your backup for example).

The script above only works on the local machine because making links on a remote machine needs some extra work. But not much:

#!/bin/sh

date=`date " %Y-%m-%dT%H:%M:%S"`
rsync -azP --link-dest=PATHTOBACKUP/current $SOURCE $HOST:PATHTOBACKUP/back-$date
ssh $HOST "rm -f PATHTOBACKUP/current && ln -s back-$date PATHTOBACKUP/current"

The -f parameter for the rm command is used to supress error messages if the current directory is not present, which would in turn prevent the link to be created.

To get that working you either use a public/private key authentication scheme or something else to avoid typing in your password. Another possibility is, of course, to mount the remote file-system on the local computer using the above script.

On my setup the script takes about 6 seconds to synchronize 46968 files and 29GB %u2013 this takes 20MB for the file structure (with no actual files to transfer of course). But afterwards, I have a complete backup of my system in a new directory.

On a much bigger setup (1.2 million files and 50GB of data) the backup takes about 30 minutes and takes about 3GB of space (just for links!), so it isn%u2019t exactly free, but very convenient.

The space needed for the backup is determined by the shape of your directory structure. On the larger setup I have lots of Maildirs and a very deep directory structure so it takes much more space than my home-directory backup above. 3GB is quite a lot, but 20MB doesn%u2019t hurt.

Advanced rsync parameters

Additional to the parameters described above, I usually employ a combination of these parameters in my backup:

• --delete and --delete-excluded this tells rsync to remove files from my backups either if they are gone on my local machine, or if I decided to exclude them from my backup.
• --exclude-from=FILE the file specified here is a simple list of directories of files (one per line) which should not be backed up. My Trash folder oder some .cache folders are candidates for this file.
• -P is used to give more information on how far the backup is, and how many files are to be backed up. Additional it could resume an interrupted transfer (which doesn%u2019t apply here because we create a blank backup each time we call the script).
• -x this one is important because it prohibits rsync to go beyond the local filesystem. For example if you backup you Linux-root partition, you should not include the /proc directory because rsync will get stuck in it. -x excludes all mounted filesystems from the backup which is probably what you want in most cases.

Hard-Links

Each file in a directory is a link to the actual data on your hard-disk. The file-system keeps track of how many links to a area point, and only if the last link is deleted, the whole area gets deleted (in contrast to soft-links, these are pointers to the file-name, not the contents).

Here an illustration of two backups with three files each. File1 and File2 are the same in both backups, only File3 changed between Backup1 and Backup2. So in Backup2, File3 (changed) has to point to a different area than File3 in Backup1.

BTW, there is a nice project for Linux out there which provides the same functionality as Time Machine including a nice GUI which is also based on rsync and the procedure presented here.

The End

Credit: The initial idea for this approach came from Mike Rubel %u2013 rsync snapshots.

Also interesting if you have to cope with Windows: Optimal remote backups with rsync over Samba.

There are quite a few approaches out there which more or less do the same, but rsync is available on virtually every Unix out there (even the DSL with its 50MB footprint includes rsync). So using other tools might be more convenient, but I%u2019ll stick with the omnipresent rsync.

rsync offers the possibility to store only the differences to the previous backup (using --compare-dest which should point to a full-backup instead of --link-dest). It then doesn%u2019t make links to the unchanged files, it just leaves them out. This way you get an incremental backup without the %u201Cdirectory-overhead%u201D of the --link-dest approach. But you have to be extremely cautious which one of older backups you delete because the newer backups just don%u2019t contain some of these files (think of full-backups as checkpoints)! Using the --link-dest you can delete all backups but the last and you still got all the files, so I%u2019m happy to pay 20MB per backup for this safety.

Full script

Here my full script with additional features:

#!/bin/sh

date=`date " %Y-%m-%dT%H_%M_%S"`
HOME=/home/user/

rsync -azP \
  --delete \
  --delete-excluded \
  --exclude-from=$HOME/.rsync/exclude \
  --link-dest=../current \
  $HOME user@backupserver:Backups/incomplete_back-$date \
  && ssh user@backupserver \
  "mv Backups/incomplete_back-$date Backups/back-$date \
  && rm -f Backups/current \
  && ln -s back-$date Backups/current"

The universe tends toward maximum irony. Don%u2019t push it.
%u2014 JWZ

am crazy bout backups n it sucks if u lose precious data esp family pics and videos :(

Using rsync simply copies all files from my main drive to my backup drive.

A friend suggested getting a RAID for my photos and videos!
I trust using 2 independent drives more :D

Google CEO Eric Schmidt has just posted this very intriguing tweet:

Can’t wait to watch the Superbowl tomorrow. Be sure to watch the ads in the 3rd quarter (someone said “Hell has indeed frozen over.”)

Great ad, simple and touching. I like it.

Checkout thesuperbowl videos at

http://video.google.com/superbowl.html

Dual-core ARM CPU, runs Unreal Engine 3, Full HD playback and longer battery life
New Tegra 2 chips promise to deliver lightening-fast browsing (depends upon your connection, too), Adobe Flash Player 10.1 acceleration, support for 3D touch interfaces, streaming 1080p HD video, and non-compromised graphics for 3D gaming on mobile platform. During the presentation, Tim Sweeney, Epic Games Founder and CEO showed Unreal Engine 3 running on Tegra 2 powered tablet.

Nvidia boasts that Tegra 2 gives four times the performance of previous generation Tegra processors and is ten times faster than the CPUs used in smartphones today. This is due to the 32-bit LP-DDR2 memory controller that offers higher speeds at lower power consumption. Hence, we shall see if Nvidia Tegra 2 based smartphone/MID would beat the performance of Qualcomm's 1GHz Snapdragon based Toshiba TG01.