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  • Should I worry about the integrity of my linux software RAID5 after a crash or kernel panic?

    - by Josh
    I have a dual core Intel i5 Ubuntu Server 10.04 LTS system running kernel 2.6.32-22-server #33-Ubuntu SMP with three 1TB SATA hard drives set up in a RAID5 array using linux md devices. I have read about the RAID5 write hole and am concerned: if my linux system locks up or kernel panics, should I be assume that the integrety of my data has been compromised and restore from backup? How can I know if the data on the RAID5 array is "safe"?

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  • Resize a RAID 1 volume on OS X Snow Leopard - how? (Note: software raid)

    - by Emmel
    I've scoured the Internet in search of an answer to this question, and as usual with OSX-related topics, I often don't find any deep-dive technical explanations sufficient enough to feel confident doing dangerous things. Here is my question: I have a Mac Pro, running OS X 10.6.2. I have, as my main root/boot disk, a RAID 1 volume called "Mirror1". Mirror1 is comprised of two 1 TB disks. Mirror1, however, is fixed at 640 GB. That's because, I originally took a 640GB disk, bought a terabyte disk, mirrored it (using diskutil appleraid enable), when it synced I removed the 640GB and replaced it with a second 1 TB disk, and synced again. Voila! A single 640 GB replaced by two 1 TB disks in a mirror.. Actually, no. There's still something missing from the equation: Mirror1 needs to be expanded from 640GB to 1 TB to match the partition sizes on each of those disks. How do I do this? Perhaps the diskutil output will help: -> diskutil list /dev/disk0 #: TYPE NAME SIZE IDENTIFIER 0: GUID_partition_scheme *1.0 TB disk0 1: EFI 209.7 MB disk0s1 2: Apple_RAID 999.9 GB disk0s2 3: Apple_Boot Boot OSX 134.2 MB disk0s3 /dev/disk1 #: TYPE NAME SIZE IDENTIFIER 0: GUID_partition_scheme *1.0 TB disk1 1: EFI 209.7 MB disk1s1 2: Apple_RAID 999.9 GB disk1s2 3: Apple_Boot Boot OSX 134.2 MB disk1s3 /dev/disk2 #: TYPE NAME SIZE IDENTIFIER 0: GUID_partition_scheme *640.1 GB disk2 1: EFI 209.7 MB disk2s1 2: Apple_HFS Mac Disk 2 536.7 GB disk2s2 3: Microsoft Basic Data BOOTCAMP 103.1 GB disk2s3 /dev/disk3 #: TYPE NAME SIZE IDENTIFIER 0: Apple_HFS Mirror1 *639.8 GB disk3 -> diskutil appleraid list AppleRAID sets (1 found) =============================================================================== Name: Macintosh HD Unique ID: 1953F864-B474-4EB6-8E69-41834EBD0247 Type: Mirror Status: Online Size: 639.8 GB (639791038464 Bytes) Rebuild: manual Device Node: disk3 ------------------------------------------------------------------------------- # Device Node UUID Status ------------------------------------------------------------------------------- 0 disk1s2 25109BAE-5697-40EA-B612-0217851444F7 Online 1 disk0s2 11B83AB0-8148-4DB6-8761-DEF08C855F8D Online =============================================================================== Thanks in advance.

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  • Resize a RAID 1 volume on OS X Snow Leopard - how? (Note: software raid)

    - by Emmel
    I've scoured the Internet in search of an answer to this question, and as usual with OSX-related topics, I often don't find any deep-dive technical explanations sufficient enough to feel confident doing dangerous things. Here is my question: I have a Mac Pro, running OS X 10.6.2. I have, as my main root/boot disk, a RAID 1 volume called "Mirror1". Mirror1 is comprised of two 1 TB disks. Mirror1, however, is fixed at 640 GB. That's because, I originally took a 640GB disk, bought a terabyte disk, mirrored it (using diskutil appleraid enable), when it synced I removed the 640GB and replaced it with a second 1 TB disk, and synced again. Voila! A single 640 GB replaced by two 1 TB disks in a mirror.. Actually, no. There's still something missing from the equation: Mirror1 needs to be expanded from 640GB to 1 TB to match the partition sizes on each of those disks. How do I do this? Perhaps the diskutil output will help: -> diskutil list /dev/disk0 #: TYPE NAME SIZE IDENTIFIER 0: GUID_partition_scheme *1.0 TB disk0 1: EFI 209.7 MB disk0s1 2: Apple_RAID 999.9 GB disk0s2 3: Apple_Boot Boot OSX 134.2 MB disk0s3 /dev/disk1 #: TYPE NAME SIZE IDENTIFIER 0: GUID_partition_scheme *1.0 TB disk1 1: EFI 209.7 MB disk1s1 2: Apple_RAID 999.9 GB disk1s2 3: Apple_Boot Boot OSX 134.2 MB disk1s3 /dev/disk2 #: TYPE NAME SIZE IDENTIFIER 0: GUID_partition_scheme *640.1 GB disk2 1: EFI 209.7 MB disk2s1 2: Apple_HFS Mac Disk 2 536.7 GB disk2s2 3: Microsoft Basic Data BOOTCAMP 103.1 GB disk2s3 /dev/disk3 #: TYPE NAME SIZE IDENTIFIER 0: Apple_HFS Mirror1 *639.8 GB disk3 -> diskutil appleraid list AppleRAID sets (1 found) =============================================================================== Name: Macintosh HD Unique ID: 1953F864-B474-4EB6-8E69-41834EBD0247 Type: Mirror Status: Online Size: 639.8 GB (639791038464 Bytes) Rebuild: manual Device Node: disk3 ------------------------------------------------------------------------------- # Device Node UUID Status ------------------------------------------------------------------------------- 0 disk1s2 25109BAE-5697-40EA-B612-0217851444F7 Online 1 disk0s2 11B83AB0-8148-4DB6-8761-DEF08C855F8D Online =============================================================================== Thanks in advance.

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  • How to make a Linux software RAID1 detect disc corruption?

    - by Paul
    This is one of the nightmare days: A virtualized server running on a Linux SW-RAID1 runs a VM that exhibits random segfaults in seemingly random codechunks. While debugging I find that a file gives different md5sums on each and every run. Digging deeper I find this: The raw disc partitions that make up the RAID1 mirror contain 2 bit-differences and ca. 9 sectors are completely empty on one disc and filled with data on the other disc. Obviously Linux gives back a sector from a undeterministically chosen disc of the mirror set. So sometimes the same sector is returned OK, sometimes the corrupted is given back. The docs say: RAID cannot and is not supposed to guard against data corruption on the media. Therefore, it doesn't make any sense either, to purposely corrupt data (using dd for example) on a disk to see how the RAID system will handle that. It is most likely (unless you corrupt the RAID superblock) that the RAID layer will never find out about the corruption, but your filesystem on the RAID device will be corrupted. Thanks. That will help me sleep. :-/ Is there a way to have Linux at least detect this corruption by using sector checksumming or something like that? Would this be detected in a RAID5 setup? Is this the moment I wish I used ZFS or btrfs (once it becomes usable without uber-admin capabilities)?

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  • Is Software Raid1 Using mdadm with a Local Hard Disk and GNDB Possible?

    - by Travis
    I have multiple webservers which use many small files to created dynamic web pages. Caching the web pages isn't an option. The webserver also performs writes so I need a synchronous filesystem. I'm looking to maximise performance as it's my understanding that small files is the weakness (to varying degreess) of a cluster filesystem over ethernet. Currently I'm using Centos 5.5, 64 bit. Since it's only about 300MB of data, I'm looking at mdadm using RAID-1 with the GNBD and a local hard disk using the "--write-mostly" option so the reads are done using the local hard disk. Is this possible? If so, is there any advantage to making it a tmpfs disk instead of a local hard disk? Or will the files on the local hard disk just get cached in RAM anyway so I won't see a performance gain by using tmpfs, assuming there's enough RAM available?

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  • Resize a RAID 1 volume on OSX Snow Leopard - how? (Note: software raid)

    - by Emmel
    I've scoured the Internet in search of an answer to this question, and as usual with OSX-related topics, I often don't find any deep-dive technical explanations sufficient enough to feel confident doing dangerous things. Here is my question: I have a Mac Pro, running OSX 10.6.2. I have, as my main root/boot disk, a RAID 1 volume called "Mirror1". Mirror1 is comprised of two 1 TB disks. Mirror1, however, is fixed at 640 GB. That's because, I originally took a 640GB disk, bought a terabyte disk, mirrored it (using diskutil appleraid enable...), when it synced I removed the 640GB and replaced it with a second 1 TB disk, and synced again. Voila! A single 640 GB replaced by two 1 TB disks in a mirror.. Actually, no. There's still something missing from the equation: Mirror1 needs to be expanded from 640GB to 1 TB to match the partition sizes on each of those disks. How do I do this? Perhaps the diskutil output will help: -> diskutil list /dev/disk0 #: TYPE NAME SIZE IDENTIFIER 0: GUID_partition_scheme *1.0 TB disk0 1: EFI 209.7 MB disk0s1 2: Apple_RAID 999.9 GB disk0s2 3: Apple_Boot Boot OSX 134.2 MB disk0s3 /dev/disk1 #: TYPE NAME SIZE IDENTIFIER 0: GUID_partition_scheme *1.0 TB disk1 1: EFI 209.7 MB disk1s1 2: Apple_RAID 999.9 GB disk1s2 3: Apple_Boot Boot OSX 134.2 MB disk1s3 /dev/disk2 #: TYPE NAME SIZE IDENTIFIER 0: GUID_partition_scheme *640.1 GB disk2 1: EFI 209.7 MB disk2s1 2: Apple_HFS Mac Disk 2 536.7 GB disk2s2 3: Microsoft Basic Data BOOTCAMP 103.1 GB disk2s3 /dev/disk3 #: TYPE NAME SIZE IDENTIFIER 0: Apple_HFS Mirror1 *639.8 GB disk3 -> diskutil appleraid list AppleRAID sets (1 found) =============================================================================== Name: Macintosh HD Unique ID: 1953F864-B474-4EB6-8E69-41834EBD0247 Type: Mirror Status: Online Size: 639.8 GB (639791038464 Bytes) Rebuild: manual Device Node: disk3 ------------------------------------------------------------------------------- # Device Node UUID Status ------------------------------------------------------------------------------- 0 disk1s2 25109BAE-5697-40EA-B612-0217851444F7 Online 1 disk0s2 11B83AB0-8148-4DB6-8761-DEF08C855F8D Online =============================================================================== Thanks in advance.

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  • Fan is spinning too fast just in Windows - software?

    - by B. Roland
    I've recently replaced my fans (CPU, GPU, and bought a CHA fan). The GPU remained the same, but I've seen it when it was spinned 2 times faster, than it usual... but it is rarely. The problem is, that the CPU fan in Windows (especially 7) spinned too much, 'cos it keeps in under 40°C, and it is spinning with 3300-3600 RPM, which is too high I think. If I swich to Ubuntu, it keeps on ~40-45°C with with 2500-2800 RPM, which is a big difference in numbers, and in noise. I'm looking for a manual fan control solution, or just reduce the Windows' multipliers of fan speed control, somehow... I was bought the new fans because of the lower noise (and it does it, but not with 3.6k RMP). Thank you!

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  • Linux Software Raid runs checkarray on the First Sunday of the Month? Why?

    - by mgjk
    It looks like Debian has a default to run checkarray on the first Sunday of the month. This causes massive performance problems and heavy disk usage for 12 hours on my 2TB mirror. Doing this "just in case" is bizzare to me. Discovering data out of sync between the two disks without quorum would be a failure anyway. This massive checking could only tell me that I have an unrecoverable drive failure and corrupt data. Which is nice, but not all that helpful. Is it necessary? Given I have no disk errors and no reason to believe my disks have failed, why is this check necessary? Should I take it out of my cron? /etc/cron.d# tail -1 /etc/cron.d/mdadm 57 0 * * 0 root [ -x /usr/share/mdadm/checkarray ] && [ $(date +\%d) -le 7 ] && /usr/share/mdadm/checkarray --cron --all --quiet Thanks for any insight,

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  • How to disable automatic and forced fsck on disks in a linux software raid?

    - by mit
    This is the /etc/fstab entry of a raid system /dev/md4 that is controlled with mdadm and webmin on an ubuntu 10.04 64 server: /dev/md4 /mnt/md4 ext3 relatime 0 0 We tried to switch off automatic forced fsck on rebotts, as we prefer to implement our own scheduled fsck routine by setting the last parameter of the line to 0 (ZERO). But we found out the forced and automatic check still occurs on the underlying real disks, lets say sdb1 and sdc1. How can we switch that off?

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  • Is there a piece of software which lets you turn "anything" into a dynamic reorderable list?

    - by Robin Green
    I could write this myself, but I want to know if it already exists. Basically, it must fulfill these criteria: To reorder items, the user must never have to manually renumber them. That would be annoying, and it doesn't scale. Can read from a range of data sources (e.g. a database, a directory on the file system, a text file, another list) When the original data source changes, the list must automatically change with it (possibly with confirmation, e.g. if a list item would be deleted) Ability to persist the list ordering in some fashion Graphical display of list items (so that they can include e.g. images) Optional extras: Ability to modify data and write back to the data source (other than the ordering information)

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  • Linux mdadm software RAID 6 - does it support bit corruption recovery?

    - by user101203
    Wikipedia says "RAID 2 is the only standard RAID level, other than some implementations of RAID 6, which can automatically recover accurate data from single-bit corruption in data." Does anyone know if the RAID 6 mdadm implementation in Linux is one such implementation that can automatically detect and recover from single-bit data corruption. This pertains to CentOS / Red Hat 6 if those are different from other versions. I tried searching online but didn't have much luck. With SATA error rates being 1 in 1E14 bits, and a 2TB SATA disk containing 1.6E13 bits, this is especially relevant to preventing data corruption. Thanks!

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  • Is it possible to use software raid in Windows 7 on the boot partition?

    - by DoctaJonez
    I want to use RAID 1 on my workstation configuration at work, and I've been looking at using the build in mirror functionality in Windows 7. When you click on the add mirror option it presents you with the following warning. I've done some Google searching and the consensus seems to be that you cannot boot from a dynamic volume, but some forum posts seem to indicate that people have tried this with success (e.g. here). With Google searches producing contradictory information I thought I'd ask you guys for an authoritative answer. Can I use the inbuilt Windows 7 mirroring for my boot partition? Or as I suspect, will it make it unbootable due to it being converted to a dynamic disk?

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  • Linux software RAID6: 3 drives offline - how to force online?

    - by Ole Tange
    This is similar to 3 drives fell out of Raid6 mdadm - rebuilding? except that it is not due to a failing cable. Instead the 3rd drive fell offline during rebuild of another drive. The drive failed with: kernel: end_request: I/O error, dev sdc, sector 293732432 kernel: md/raid:md0: read error not correctable (sector 293734224 on sdc). After rebooting both these sectors and the sectors around them are fine. This leads me to believe the error is intermittent and thus the device simply took too long to error correct the sector and remap it. I expect that no data was written to the RAID after it failed. Therefore I hope that if I can kick the last failing device online that the RAID is fine and that the xfs_filesystem is OK, maybe with a few missing recent files. Taking a backup of the disks in the RAID takes 24 hours, so I would prefer that the solution works the first time. I have therefore set up a test scenario: export PRE=3 parallel dd if=/dev/zero of=/tmp/raid${PRE}{} bs=1k count=1000k ::: 1 2 3 4 5 parallel mknod /dev/loop${PRE}{} b 7 ${PRE}{} \; losetup /dev/loop${PRE}{} /tmp/raid${PRE}{} ::: 1 2 3 4 5 mdadm --create /dev/md$PRE -c 4096 --level=6 --raid-devices=5 /dev/loop${PRE}[12345] cat /proc/mdstat mkfs.xfs -f /dev/md$PRE mkdir -p /mnt/disk2 umount -l /mnt/disk2 mount /dev/md$PRE /mnt/disk2 seq 1000 | parallel -j1 mkdir -p /mnt/disk2/{}\;cp /bin/* /mnt/disk2/{}\;sleep 0.5 & mdadm --fail /dev/md$PRE /dev/loop${PRE}3 /dev/loop${PRE}4 cat /proc/mdstat # Assume reboot so no process is using the dir kill %1; sync & kill %1; sync & # Force fail one too many mdadm --fail /dev/md$PRE /dev/loop${PRE}1 parallel --tag -k mdadm -E ::: /dev/loop${PRE}? | grep Upda # loop 2,5 are newest. loop1 almost newest => force add loop1 Next step is to add loop1 back - and this is where I am stuck. After that do a xfs-consistency check. When that works, check that the solution also works on real devices (such a 4 USB sticks).

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  • Hobbyist programmer releasing software with a donate button

    - by espais
    I'd like to start this with a disclaimer that I realize that a full, clear-cut answer should be sought out by a lawyer. I am more so curious about what other users of this community have done Say that I had a small program that I had developed for fun, that I wished to release to the public. I'll drop it out there with one of the various open-source licenses, and probably put it up on SourceForge or Git in case if anybody should ever want to fork/maintain/check out code. Also say that I wanted to accept donations for the project, with absolutely 0 expectation that people will send any money. However, if somebody donated in order to buy me a beer or a pizza for the work that they liked, I would accept gladly. The question, then, is what are the general requirements of accepting donations? Can it go into a personal account with no questions asked as a "gift," or do I need to setup an LLC to avoid any taxation issues? (US citizen here). Again, yes this should be lawyer discussed, but I also know that many projects that I see have the ability to donate, and assume that the community probably has a decent amount of experience in this regard.

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  • ASP.NET MVC 3 (C#) Software Architecture

    - by ryanzec
    I am starting on a relatively large and ambitious ASP.NET MVC 3 project and just thinking about the best way to organize my code. The project is basically going to be a general management system that will be capable of supporting any type management system whether it be a blogging system, cms, reservation system, wikis, forums, project management system, etc…, each of them being just a separate 'module'. You can read more about it on my blog posted here : http://www.ryanzec.com/index.php/blog/details/8 (forgive me, the style of the site kinda sucks). For those who don't want to read the long blog post the basic idea is that the core system itself is nothing more than a users system with an admin interface to manage the users system. Then you just add on module as you need them and the module I will be creating is a simple blog post to test it out before I move on to the big module which is a project management system. Now I am just trying to think of the best way to structure this so that it is easy for users to add in there own modules but easy for me to update to core system without worrying about the user modifying the core code. I think the ideal way would be to have a number of core projects that user is specifically told not to modify otherwise the system may become unstable and future updates would not work. When the user wants to add in there own modules, they would just add in a new project (or multiple projects). The thing is I am not sure that it is even possible to use multiple projects all with their own controllers, razor view template, css, javascript, etc... in one web application. Ideally each module would have some of it own razor view templates, css, javascript, image files and also need access to some of the core razor view templates, css, javascript, image files which would is in a separate project. It is possible to have 1 web application run off of controllers, razor view templates, css, javascript, image files that are store in multiple projects? Is there a better was to structure this to allow the user to easily add in module with having to modify the core code?

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  • Areas of support needed when attempting to roll out a new software system

    In general, I think most people tend to be resistant to new systems or even change because they fear the unknown. Change means that their normal routine will be interrupted until they can learn to conform to the new routine due to the fact that it has transformed to the old routine. In addition, the feeling of failure is also generates a resistance to change. Why would a worker want to move from a process that has worked successfully for them in the past? Their fears over shadow any benefits a change in a new system or business process will bring to their work life. Areas of support needed when attempting to roll out a new software system: Executive/Upper Management Support If there is no support from the top of an organization how will employees be supportive of the new system? Proper Training Employees need to train on a new system prior to its rollout. The more training employee’s receive on any new system will directly impact how comfortable they will be with the system and are more accepting of the change because they can see how the changes will benefit them. Employee Incentives One way to re-enforce the need for employees to use a new system is to offer incentives to ensure that the system will be used. Employee Discipline/Termination If employees are adamantly refusing to use the new system after several warnings then they need to be formally reprimanded.  If this does not work the employer is forced to replace the employees.

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  • Four New Java Champions

    - by Tori Wieldt
    Four luminaries in the Java community have been selected as new Java Champions. The are Agnes Crepet, Lars Vogel, Yara Senger and Martijn Verburg. They were selected for their technical knowledge, leadership, inspiration, and tireless work for the community. Here is how they rock the Java world: Agnes Crepet Agnes Crepet (France) is a passionate technologist with over 11 years of software engineering experience, especially in the Java technologies, as a Developer, Architect, Consultant and Trainer. She has been using Java since 1999, implementing multiple kinds of applications (from 20 days to 10000 men days) for different business fields (banking, retail, and pharmacy). Currently she is a Java EE Architect for a French pharmaceutical company, the homeopathy world leader. She is also the co-founder, with other passionate Java developers, of a software company named Ninja Squad, dedicated to Software Craftsmanship. Agnes is the leader of two Java User Groups (JUG), the Lyon JUG Duchess France and the founder of the Mix-IT Conferenceand theCast-IT Podcast, two projects about Java and Agile Development. She speaks at Java and JUG conferences around the world and regularly writes articles about the Java Ecosystem for the French print Developer magazine Programmez! and for the Duchess Blog. Follow Agnes @agnes_crepet. Lars Vogel Lars Vogel (Germany) is the founder and CEO of the vogella GmbH and works as Java, Eclipse and Android consultant, trainer and book author. He is a regular speaker at international conferences, such as EclipseCon, Devoxx, Droidcon and O'Reilly's Android Open. With more than one million visitors per month, his website vogella.com is one of the central sources for Java, Eclipse and Android programming information. Lars is committer in the Eclipse project and received in 2010 the "Eclipse Top Contributor Award" and 2012 the "Eclipse Top Newcomer Evangelist Award." Follow Lars on Twitter @vogella. Yara Senger Yara Senger (Brazil) has been a tireless Java activist in Brazil for many years. She is President of SouJava and she is an alternate representative of the group on the JCP Executive Committee. Yara has led SouJava in many initiatives, from technical events to social activities. She is co-founder and director of GlobalCode, which trains developers throughout Brazil.  Last year, she was recipient of the Duke Choice's Award, for the JHome embedded environment.  Yara is also an active speaker, giving presentations in many countries, including JavaOne SF, JavaOne Latin Ameria, JavaOne India, JFokus, and JUGs throughout Brazil. Yara is editor of InfoQ Brasil and also frequently posts at http://blog.globalcode.com.br/search/label/Yara. Follow Yara @YaraSenger. Martijn Verburg Martijn Verburg (UK) is the CTO of jClarity (a Java/JVM performance cloud tooling start-up) and has over 12 years experience as a Java/JVM technology professional and OSS mentor in a variety of organisations from start-ups to large enterprises. He is the co-leader of the London Java Community (~2800 developers) and leads the global effort for the Java User Group "Adopt a JSR" and "Adopt OpenJDK" programmes. These programmes encourage day to day Java developer involvement with OpenJDK, Java standards (JSRs), an important relationship for keeping the Java ecosystem relevant to the 9 million Java developers out there today. As a leading expert on technical team optimisation, his talks and presentations are in high demand by major conferences (JavaOne, Devoxx, OSCON, QCon) where you'll often find him challenging the industry status quo via his alter ego "The Diabolical Developer." You can read more in the OTN ariticle "Challenging the Diabolical Developer: A Conversation with JavaOne Rock Star Martijn Verburg." Follow Martijn @karianna. The Java Champions are an exclusive group of passionate Java technology and community leaders who are community-nominated and selected under a project sponsored by Oracle. Java Champions get the opportunity to provide feedback, ideas, and direction that will help Oracle grow the Java Platform. Congratulations to these new Java Champions!

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  • RPi and Java Embedded GPIO: Big Data and Java Technology

    - by hinkmond
    Java Embedded and Big Data go hand-in-hand, especially as demonstrated by prototyping on a Raspberry Pi to show how well the Java Embedded platform can perform on a small embedded device which then becomes the proof-of-concept for industrial controllers, medical equipment, networking gear or any type of sensor-connected device generating large amounts of data. The key is a fast and reliable way to access that data using Java technology. In the previous blog posts you've seen the integration of a static electricity sensor and the Raspberry Pi through the GPIO port, then accessing that data through Java Embedded code. It's important to point out how this works and why it works well with Java code. First, the version of Linux (Debian Wheezy/Raspian) that is found on the RPi has a very convenient way to access the GPIO ports through the use of Linux OS managed file handles. This is key in avoiding terrible and complex coding using register manipulation in C code, or having to program in a less elegant and clumsy procedural scripting language such as python. Instead, using Java Embedded, allows a fast way to access those GPIO ports through those same Linux file handles. Java already has a very easy to program way to access file handles with a high degree of performance that matches direct access of those file handles with the Linux OS. Using the Java API java.io.FileWriter lets us open the same file handles that the Linux OS has for accessing the GPIO ports. Then, by first resetting the ports using the unexport and export file handles, we can initialize them for easy use in a Java app. // Open file handles to GPIO port unexport and export controls FileWriter unexportFile = new FileWriter("/sys/class/gpio/unexport"); FileWriter exportFile = new FileWriter("/sys/class/gpio/export"); ... // Reset the port unexportFile.write(gpioChannel); unexportFile.flush(); // Set the port for use exportFile.write(gpioChannel); exportFile.flush(); Then, another set of file handles can be used by the Java app to control the direction of the GPIO port by writing either "in" or "out" to the direction file handle. // Open file handle to input/output direction control of port FileWriter directionFile = new FileWriter("/sys/class/gpio/gpio" + gpioChannel + "/direction"); // Set port for input directionFile.write("in"); // Or, use "out" for output directionFile.flush(); And, finally, a RandomAccessFile handle can be used with a high degree of performance on par with native C code (only milliseconds to read in data and write out data) with low overhead (unlike python) to manipulate the data going in and out on the GPIO port, while the object-oriented nature of Java programming allows for an easy way to construct complex analytic software around that data access functionality to the external world. RandomAccessFile[] raf = new RandomAccessFile[GpioChannels.length]; ... // Reset file seek pointer to read latest value of GPIO port raf[channum].seek(0); raf[channum].read(inBytes); inLine = new String(inBytes); It's Big Data from sensors and industrial/medical/networking equipment meeting complex analytical software on a small constraint device (like a Linux/ARM RPi) where Java Embedded allows you to shine as an Embedded Device Software Designer. Hinkmond

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  • SQLAuthority News – Pluralsight Course Review – Practices for Software Startups – Part 2 of 2

    - by pinaldave
    This is the second part of the two part series of Practices for Software Startup Pluralsight Course. Please read the first part of this series over here. The course is written by Stephen Forte (Blog | Twitter). Stephen Forte is the Chief Strategy Officer of the venture backed company, Telerik. Personal Learning Schedule After these three sessions it was 6:30 am and time to do my own blog.  But for the rest of the day, I kept thinking about the course, and wanted to go back and finish.  I was wishing that I had woken up at 3 am so I could finish all at one go.  All day long I was digesting what I had learned.  At 10 pm, after my daughter had gone to bed, I sighed on again.  I was not disappointed by the long wait.  As I mentioned before, Stephen has started four to six companies, and all of them are very successful today. Here is the video I promised yesterday – it discusses the importance of Right Sizing Your Startup. The Heartbeat of Startup – Technology Stephen has combined all technology knowledge into one 30 minute session.  He discussed  how to start your project, how to deal with opinions, and how to deal with multiple ideas – every start up has multiple directions it can go. He spent a lot of time emphasized deciding which direction to go and how to decide which will be the best for you.  He called it a continuous development cycle. One of the biggest hazards for a start-up company is one person deciding the direction the company will go, until down the road another team member announces that there is a glitch in their part of the work and that everyone will have to start over.  Even though a team of two or five people can move quickly, often the decision has gone too long and cannot be easily fixed.   Stephen used an example from his own life:  he was biased for one type of technology, and his teammate for another.  In the end they opted for his teammate’s  choice , and in the end it was a good decision, even though he was unfamiliar with that particular program.  He argues that technology should not be a barrier to progress, that you cannot rely on your experience only.  This really spoke to me because I am a big fan of SQL, but I know there is more out there, and I should be more open to it.  I give my thanks to Stephen, I learned something in this module besides startups. Money, Success and Epic Win! The longest, but most interesting, the module was funding your start-up.  You need to fund the start-up right at the very beginning, if not done right you will run into trouble.  The good news is that a few years ago start-ups required a lot more money – think millions of dollars – but now start-ups can get off the ground for thousands.  Stephen used an example of a company that years ago would have needed a million dollars, but today could be started for $600.  It is true that things have changed, but you still need money.  For $600 you can start small and add dynamically, as needed.  But the truth is that if you have $600, $6000, or $6 million, it will be spent.  Don’t think of it as trying to save money, think of it as investing in your future.   You will need money, and you will need to (quickly) decide what you do with the money: shares, stakeholders, investing in a team, hiring a CEO.  This is so important because once you have money and start the company, the company IS your money.  It is your biggest currency – having a percentage of ownership in the company.  Investors will want percentages as repayment for their investment, and they will want a say in the business as well.  You will have to decide how far you will dilute your shares, and how the company will be divided, if at all.  If you don’t plan in advance, you will find that after gaining three or four investors, suddenly you are the minority owner in your own dream.  You need to understand funding carefully.  This single module is worth all the money you would have spent on the whole course alone.  I encourage everyone to listen to this single module even if they don’t watch any of the others.     Press End to Start the Game – Exists! The final module is exit strategies.  You did all this work, dealt with all political and legal issues.  What are you going to get out of it? The answer is simple: money.  Maybe you want your company to be bought out, for you talent to bring you a profit.  You can sell the company to someone and still head it.  Many options are available.  You could sell and still work as an employee but no longer own the company.  There are many exit strategies.  This is where all your hard work comes into play.  It is important not to feel fooled at any step.  There are so many good ideas that end up in the garbage because of poor planning, so that if you find yourself successful, you don’t want to blow it at this step!  The exit is important.  I thought that this aspect of the course was completely unique, and I loved Stephen’s point of view.  I was lost deep in thought after this module ended.  I actually took two hours worth of notes on this section alone – and it was only a three hour course.  I am planning on attending this course one more time next week, just to catch up on all the small bits of wisdom I’m sure I missed. Thank you Stephen for bringing your real world experience with us!  I recommend that everyone attends this course, even if they don’t want to begin their own start-up company. It was indeed a long day for me. Do not forget to read part 1 of this story and attend course Practices for Software Startup Pluralsight Course. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Best Practices, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • Security in Software

    The term security has many meanings based on the context and perspective in which it is used. Security from the perspective of software/system development is the continuous process of maintaining confidentiality, integrity, and availability of a system, sub-system, and system data. This definition at a very high level can be restated as the following: Computer security is a continuous process dealing with confidentiality, integrity, and availability on multiple layers of a system. Key Aspects of Software Security Integrity Confidentiality Availability Integrity within a system is the concept of ensuring only authorized users can only manipulate information through authorized methods and procedures. An example of this can be seen in a simple lead management application.  If the business decided to allow each sales member to only update their own leads in the system and sales managers can update all leads in the system then an integrity violation would occur if a sales member attempted to update someone else’s leads. An integrity violation occurs when a team member attempts to update someone else’s lead because it was not entered by the sales member.  This violates the business rule that leads can only be update by the originating sales member. Confidentiality within a system is the concept of preventing unauthorized access to specific information or tools.  In a perfect world the knowledge of the existence of confidential information/tools would be unknown to all those who do not have access. When this this concept is applied within the context of an application only the authorized information/tools will be available. If we look at the sales lead management system again, leads can only be updated by originating sales members. If we look at this rule then we can say that all sales leads are confidential between the system and the sales person who entered the lead in to the system. The other sales team members would not need to know about the leads let alone need to access it. Availability within a system is the concept of authorized users being able to access the system. A real world example can be seen again from the lead management system. If that system was hosted on a web server then IP restriction can be put in place to limit access to the system based on the requesting IP address. If in this example all of the sales members where accessing the system from the 192.168.1.23 IP address then removing access from all other IPs would be need to ensure that improper access to the system is prevented while approved users can access the system from an authorized location. In essence if the requesting user is not coming from an authorized IP address then the system will appear unavailable to them. This is one way of controlling where a system is accessed. Through the years several design principles have been identified as being beneficial when integrating security aspects into a system. These principles in various combinations allow for a system to achieve the previously defined aspects of security based on generic architectural models. Security Design Principles Least Privilege Fail-Safe Defaults Economy of Mechanism Complete Mediation Open Design Separation Privilege Least Common Mechanism Psychological Acceptability Defense in Depth Least Privilege Design PrincipleThe Least Privilege design principle requires a minimalistic approach to granting user access rights to specific information and tools. Additionally, access rights should be time based as to limit resources access bound to the time needed to complete necessary tasks. The implications of granting access beyond this scope will allow for unnecessary access and the potential for data to be updated out of the approved context. The assigning of access rights will limit system damaging attacks from users whether they are intentional or not. This principle attempts to limit data changes and prevents potential damage from occurring by accident or error by reducing the amount of potential interactions with a resource. Fail-Safe Defaults Design PrincipleThe Fail-Safe Defaults design principle pertains to allowing access to resources based on granted access over access exclusion. This principle is a methodology for allowing resources to be accessed only if explicit access is granted to a user. By default users do not have access to any resources until access has been granted. This approach prevents unauthorized users from gaining access to resource until access is given. Economy of Mechanism Design PrincipleThe Economy of mechanism design principle requires that systems should be designed as simple and small as possible. Design and implementation errors result in unauthorized access to resources that would not be noticed during normal use. Complete Mediation Design PrincipleThe Complete Mediation design principle states that every access to every resource must be validated for authorization. Open Design Design PrincipleThe Open Design Design Principle is a concept that the security of a system and its algorithms should not be dependent on secrecy of its design or implementation Separation Privilege Design PrincipleThe separation privilege design principle requires that all resource approved resource access attempts be granted based on more than a single condition. For example a user should be validated for active status and has access to the specific resource. Least Common Mechanism Design PrincipleThe Least Common Mechanism design principle declares that mechanisms used to access resources should not be shared. Psychological Acceptability Design PrincipleThe Psychological Acceptability design principle refers to security mechanisms not make resources more difficult to access than if the security mechanisms were not present Defense in Depth Design PrincipleThe Defense in Depth design principle is a concept of layering resource access authorization verification in a system reduces the chance of a successful attack. This layered approach to resource authorization requires unauthorized users to circumvent each authorization attempt to gain access to a resource. When designing a system that requires meeting a security quality attribute architects need consider the scope of security needs and the minimum required security qualities. Not every system will need to use all of the basic security design principles but will use one or more in combination based on a company’s and architect’s threshold for system security because the existence of security in an application adds an additional layer to the overall system and can affect performance. That is why the definition of minimum security acceptably is need when a system is design because this quality attributes needs to be factored in with the other system quality attributes so that the system in question adheres to all qualities based on the priorities of the qualities. Resources: Barnum, Sean. Gegick, Michael. (2005). Least Privilege. Retrieved on August 28, 2011 from https://buildsecurityin.us-cert.gov/bsi/articles/knowledge/principles/351-BSI.html Saltzer, Jerry. (2011). BASIC PRINCIPLES OF INFORMATION PROTECTION. Retrieved on August 28, 2011 from  http://web.mit.edu/Saltzer/www/publications/protection/Basic.html Barnum, Sean. Gegick, Michael. (2005). Defense in Depth. Retrieved on August 28, 2011 from  https://buildsecurityin.us-cert.gov/bsi/articles/knowledge/principles/347-BSI.html Bertino, Elisa. (2005). Design Principles for Security. Retrieved on August 28, 2011 from  http://homes.cerias.purdue.edu/~bhargav/cs526/security-9.pdf

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  • How to refactor use of the general Exception?

    - by Colin
    Our code catches the general exception everywhere. Usually it writes the error to a log table in the database and shows a MessageBox to the user to say that the operation requested failed. If there is database interaction, the transaction is rolled back. I have introduced a business logic layer and a data access layer to unravel some of the logic. In the data access layer, I have chosen not to catch anything and I also throw ArgumentNullExceptions and ArgumentOutOfRangeExceptions so that the message passed up the stack does not come straight from the database. In the business logic layer I put a try catch. In the catch I rollback the transaction, do the logging and rethrow. In the presentation layer there is another try catch that displays a MessageBox. I am now thinking about catching a DataException and an ArgumentException instead of an Exception where I know the code only accesses a database. Where the code accesses a web service, then I thought I would create my own "WebServiceException", which would be created in the data access layer whenever an HttpException, WebException or SoapException is thrown. So now, generally I will be catching 2 or 3 exceptions where currently I catch just the general Exception, and I think that seems OK to me. Does anyone wrap exceptions up again to carry the message up to the presentation layer? I think I should probably add a try catch to Main() that catches Exception, attempts to log it, displays an "Application has encountered an error" message and exits the application. So, my question is, does anyone see any holes in my plan? Are there any obvious exceptions that I should be catching or do these ones pretty much cover it (other than file access - I think there is only 1 place where we read-write to a config file).

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  • Go Directly to Desktop Mode in Windows 8 on Login (Without Installing Extra Software)

    - by Asian Angel
    A lot of people are unhappy with being forced to interact with the new Start Screen in Windows 8 first thing once they have logged into their system. But their is a quick and simple work-around to go directly to Desktop Mode that does not require installing extra software or making changes to your system. The first thing that you will need to do is make sure that the Desktop Tile is in the left uppermost position on the Start Screen as seen here. Once the tile has been moved to that position you will need to restart/reboot your system. Once your system has restarted and you are back at the Login Screen, type in your password but do NOT click on the Arrow Button or tap the Enter Key. Instead of tapping the Enter Key simply press down on it and hold it down until you see the regular desktop. Keep in mind that you may see the Start Screen become visible for just a short moment as it is being bypassed for the desktop. How to Use an Xbox 360 Controller On Your Windows PC Download the Official How-To Geek Trivia App for Windows 8 How to Banish Duplicate Photos with VisiPic

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  • JD Edwards in the Cloud…Really Already!

    - by user709270
    Yes, there is a lot of conversation about Oracle and the cloud.  Many of you may assume that Oracle applications in the cloud  only apply to Oracle Fusion Applications.  And JD Edwards customers are curious about if, when and how JD Edwards might be offered to them as a subscription offering.  The truth of the matter is that Oracle partners today are providing a JD Edwards subscription offering.  In order to help you understand what’s available, please read on for the reader’s digest version! Let’s start with a definition.  JD Edwards EnterpriseOne is available as an Accelerate subscription.  Oracle “Accelerate” subscription is Oracle's approach for providing simple to deploy, packaged, enterprise-class software solutions to growing midsize organizations through its network of expert partners. The partners that offer Oracle  JD Edwards Accelerate Subscriptions do so via their Partner Private Clouds (PPC).  The Oracle JD Edwards cloud solutions are offered only by qualified Oracle JD Edwards partners and they provide customers a complete Oracle solution that includes license software, maintenance, hosting and other services on a monthly subscription basis.  Qualified partners must be members of Oracle PartnerNetwork, be an Oracle Accelerate solutions provider and be enabled to deliver JD Edwards applications via Oracle Business Accelerator rapid implementation technology.  Currently we have many JD Edwards partners around the globe that offer the JD Edwards Accelerate Subscription model.  To access a list of Oracle JD Edwards partners currently in this program click here.  To learn more about Oracle JD Edwards Cloud Computing read this recently published white paper:   Oracle JD Edwards Cloud Computing. Choosing a deployment strategy that fits

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