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  • Dual booting 12.10 and Win 7 - boots directly to Win 7

    - by user110174
    and thank you kindly for you help! I'll preface this with saying that I realize this is a common problem, with lots of trouble-shooting guides available online; however, after multiple attempts with different guides, I've made zero progress and am hoping to someone could help me with my specific scenario. First, my story: -Initially, I installed Ubuntu 12.10 with the "Something Else" option with no problems. Used 4 GB Swap Logical Partition, 26 GB Primary Root Partition. Wanting to trying out Mint 13, I booted into Windows from GRUB2, used the latest version of EasyBCD (v2.2) to restore the Windows 7 bootloader to the MBR, deleted the Ubuntu partitions, reformatted them in NTFS. I then created a 30 GB partition of free space for Mint. I installed Mint using the same partitioning described above for Ubuntu 12.10, using /dev/sda for the boot installation files, and everything seemed to go well, until I re-booted my computer and it went straight to Windows - I could find no way to get into Mint. So I went into windows, restored windows bootloader to the MBR w/ EasyBCD, deleted partitions, etc., as I figured I'd done enough messing around and would go with Ubuntu 12.10. Now the problem: I restarted my computer booting from the same Ubuntu USB key I originally used. Briefly, "error: "prefix" is not set" flashed on screen, and instead of being greeted with the GUI menu of "try vs. install Ubuntu", there was a menu with minimal graphics (like a BIOS menu) where I could select install, run from USB, etc. After selecting "Install Ubuntu", the familiar install wizard with a GUI came up, I partitioned my drive as described, /dev/sda for the boot installation files, install went well, rebooted and...straight to Windows. This is where I'm at. Fixes I've tried: -This guide: How can I repair grub? (How to get Ubuntu back after installing Windows?) to ensure Grub is on the MBR. I followed all steps, but still when I reboot, I go directly into Windows. -Installing 12.04 instead of 12.10 - same issue -Re-installed Ubuntu, writing the boot files to their own partition, then using EasyBCD to to add a boot option for Ubuntu using the Windows bootloader, ensuring I instruct EasyBCD to look at the partition I created with the Ubuntu installer (instructions here http://neosmart.net/wiki/display/EBCD/Ubuntu). When I reboot, I select the Ubuntu option, and it puts me in GRUB4DOS, with a cursor waiting for input. I have no idea what to put here, so I would just type "reboot" to exit out. And this is where I am now. Any clue as to why I can't boot into Ubuntu? My computer specs are: ASUS UX31A Core i7, Win 7 64 Pro, 256 GB SSD, Intel HM76 Chipset and Integrated Intel HD 4000 Graphics, 4 GB memory I've tried to be as clear as possible, but I'd be happy to provide any info that would help anyone along. Thanks for your patience in reading this! Sincerely, -MN

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  • DBCC MEMUSAGE in 2005/8 ?

    - by steveh99999
    I used to like using undocumented command DBCC MEMUSAGE in SQL 2000 to see which tables were using space in SQL data cache. In SQL 2005, this command is not longer present. Instead a DMV – sys.dm_os_buffer_descriptors – can be used to display data cache contents,  but this doesn’t quite give you the same output as DBCC MEMUSAGE. I’m also aware that you can use Quest’s spotlight tool to view a summary of data cache contents. Using  this post by Umachandar Jayachandran  of Microsoft, I was able to create the following equivalent for SQL 2005/8. I’ve wrapped Umachandar’s original query in a CTE to produce summary information :- ;WITH memusage_CTE AS (SELECT bd.database_id, bd.file_id, bd.page_id, bd.page_type , COALESCE(p1.object_id, p2.object_id) AS object_id , COALESCE(p1.index_id, p2.index_id) AS index_id , bd.row_count, bd.free_space_in_bytes, CONVERT(TINYINT,bd.is_modified) AS 'DirtyPage' FROM sys.dm_os_buffer_descriptors AS bd JOIN sys.allocation_units AS au ON au.allocation_unit_id = bd.allocation_unit_id OUTER APPLY ( SELECT TOP(1) p.object_id, p.index_id FROM sys.partitions AS p WHERE p.hobt_id = au.container_id AND au.type IN (1, 3) ) AS p1 OUTER APPLY ( SELECT TOP(1) p.object_id, p.index_id FROM sys.partitions AS p WHERE p.partition_id = au.container_id AND au.type = 2 ) AS p2 WHERE  bd.database_id = DB_ID() AND bd.page_type IN ('DATA_PAGE', 'INDEX_PAGE') ) SELECT TOP 20 DB_NAME(database_id) AS 'Database',OBJECT_NAME(object_id,database_id) AS 'Table Name', index_id,COUNT(*) AS 'Pages in Cache', SUM(dirtyPage) AS 'Dirty Pages' FROM memusage_CTE GROUP BY database_id, object_id, index_id ORDER BY COUNT(*) DESC I’m not 100% happy with the results of the above query however… I’ve noticed that on a busy BizTalk messageBox database  it will return information on pages that contain GHOST rows – . ie where data has already been deleted but has yet to be cleaned-up by a background process – I’m need to investigate further why cache on this server apparently contains so much GHOST data… For more information on the background ghost cleanup process, see this article by Paul Randall. However, I think the results of this query should still be of interest to a DBA. I have another post to come shortly regarding an example I encountered where this information proved useful to me… I notice in SQL 2008, sys.dm_os_buffer_descriptors gained an extra column – numa_mode – I’m interested to see how this is populated and how useful this column can be on a NUMA-enabled system. I’m assuming in theory you could use this column to help analyse how your tables are spread across Numa-enabled data-cache ?

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  • MySQL Cluster 7.2: Over 8x Higher Performance than Cluster 7.1

    - by Mat Keep
    0 0 1 893 5092 Homework 42 11 5974 14.0 Normal 0 false false false EN-US JA X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:Cambria; mso-ascii-font-family:Cambria; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Cambria; mso-hansi-theme-font:minor-latin; mso-ansi-language:EN-US;} Summary The scalability enhancements delivered by extensions to multi-threaded data nodes enables MySQL Cluster 7.2 to deliver over 8x higher performance than the previous MySQL Cluster 7.1 release on a recent benchmark What’s New in MySQL Cluster 7.2 MySQL Cluster 7.2 was released as GA (Generally Available) in February 2012, delivering many enhancements to performance on complex queries, new NoSQL Key / Value API, cross-data center replication and ease-of-use. These enhancements are summarized in the Figure below, and detailed in the MySQL Cluster New Features whitepaper Figure 1: Next Generation Web Services, Cross Data Center Replication and Ease-of-Use Once of the key enhancements delivered in MySQL Cluster 7.2 is extensions made to the multi-threading processes of the data nodes. Multi-Threaded Data Node Extensions The MySQL Cluster 7.2 data node is now functionally divided into seven thread types: 1) Local Data Manager threads (ldm). Note – these are sometimes also called LQH threads. 2) Transaction Coordinator threads (tc) 3) Asynchronous Replication threads (rep) 4) Schema Management threads (main) 5) Network receiver threads (recv) 6) Network send threads (send) 7) IO threads Each of these thread types are discussed in more detail below. MySQL Cluster 7.2 increases the maximum number of LDM threads from 4 to 16. The LDM contains the actual data, which means that when using 16 threads the data is more heavily partitioned (this is automatic in MySQL Cluster). Each LDM thread maintains its own set of data partitions, index partitions and REDO log. The number of LDM partitions per data node is not dynamically configurable, but it is possible, however, to map more than one partition onto each LDM thread, providing flexibility in modifying the number of LDM threads. The TC domain stores the state of in-flight transactions. This means that every new transaction can easily be assigned to a new TC thread. Testing has shown that in most cases 1 TC thread per 2 LDM threads is sufficient, and in many cases even 1 TC thread per 4 LDM threads is also acceptable. Testing also demonstrated that in some instances where the workload needed to sustain very high update loads it is necessary to configure 3 to 4 TC threads per 4 LDM threads. In the previous MySQL Cluster 7.1 release, only one TC thread was available. This limit has been increased to 16 TC threads in MySQL Cluster 7.2. The TC domain also manages the Adaptive Query Localization functionality introduced in MySQL Cluster 7.2 that significantly enhanced complex query performance by pushing JOIN operations down to the data nodes. Asynchronous Replication was separated into its own thread with the release of MySQL Cluster 7.1, and has not been modified in the latest 7.2 release. To scale the number of TC threads, it was necessary to separate the Schema Management domain from the TC domain. The schema management thread has little load, so is implemented with a single thread. The Network receiver domain was bound to 1 thread in MySQL Cluster 7.1. With the increase of threads in MySQL Cluster 7.2 it is also necessary to increase the number of recv threads to 8. This enables each receive thread to service one or more sockets used to communicate with other nodes the Cluster. The Network send thread is a new thread type introduced in MySQL Cluster 7.2. Previously other threads handled the sending operations themselves, which can provide for lower latency. To achieve highest throughput however, it has been necessary to create dedicated send threads, of which 8 can be configured. It is still possible to configure MySQL Cluster 7.2 to a legacy mode that does not use any of the send threads – useful for those workloads that are most sensitive to latency. The IO Thread is the final thread type and there have been no changes to this domain in MySQL Cluster 7.2. Multiple IO threads were already available, which could be configured to either one thread per open file, or to a fixed number of IO threads that handle the IO traffic. Except when using compression on disk, the IO threads typically have a very light load. Benchmarking the Scalability Enhancements The scalability enhancements discussed above have made it possible to scale CPU usage of each data node to more than 5x of that possible in MySQL Cluster 7.1. In addition, a number of bottlenecks have been removed, making it possible to scale data node performance by even more than 5x. Figure 2: MySQL Cluster 7.2 Delivers 8.4x Higher Performance than 7.1 The flexAsynch benchmark was used to compare MySQL Cluster 7.2 performance to 7.1 across an 8-node Intel Xeon x5670-based cluster of dual socket commodity servers (6 cores each). As the results demonstrate, MySQL Cluster 7.2 delivers over 8x higher performance per data nodes than MySQL Cluster 7.1. More details of this and other benchmarks will be published in a new whitepaper – coming soon, so stay tuned! In a following blog post, I’ll provide recommendations on optimum thread configurations for different types of server processor. You can also learn more from the Best Practices Guide to Optimizing Performance of MySQL Cluster Conclusion MySQL Cluster has achieved a range of impressive benchmark results, and set in context with the previous 7.1 release, is able to deliver over 8x higher performance per node. As a result, the multi-threaded data node extensions not only serve to increase performance of MySQL Cluster, they also enable users to achieve significantly improved levels of utilization from current and future generations of massively multi-core, multi-thread processor designs.

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  • Tutorial: Controlling Your Linux System With fstab

    The /etc/fstab file gives you control over what filesystems are mounted at startup on your Linux system, including Windows partitions and network shares. You can also use it to control the mount points of removable storage devices like USB sticks and external hard disks. Akkana Peck shows us how.

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  • Best partition Scheme for Ubuntu Server

    - by K.K Patel
    I am going to deploy Ubuntu server having Following servers on it Bind server, dhcp server, LAMP Server, Openssh Server, Ldap server, Monodb database, FTP server,mail server, Samba server, NFS server , in future I want to set Openstack for PAAS. Currently I have Raid 5 with 10TB. How should I make my Partition Scheme So never get problem in future and easily expand Storage size. Suggest me such a partition Scheme with giving specific percentage of Storage to partitions like /, /boot, /var, /etc. Thanks In advance

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  • Installing Ubuntu 12.04 on NUC intel i3 DC3217IYE

    - by Kieron
    System: NUC i3, 2 hdmi ports, ethernet, no wireless. UEFI boot 2x2gb ram 30gb mSATA internal drive Ubuntu 64bit 12.04.03 Hello i am having much trouble loading an OS on my NUC. I started out attempting another OS with various loaders (beast/hack) without much success,(various panics on boot or endless reboot loops, or graphics failures) after many tries i decided to attempt Ubuntu. Many years ago i loaded Ubuntu on an e-machine without an issue so i figured it would go smoothly, nothing could be further from the truth. The Live USB stick loads, but when i am installing the OS it always fails to load grub 2. Obviously it wont boot from SSD without grub2. I searched and found that Boot-repair should fix it...so i created a live usb with boot repair...it refuses to repair the grub because the install never finished and the needed partions are not fully created and flagged. It also demands an internet connection which i am unable to provide. I then ran gparted in an attempt to create the needed partitions manually, then re-ran boot repair turning off the "check internet" option. and disabling the re-install grub hoping it would create the missing directories and or fix the flags. it appeared to run successfully but upon return to the Ubuntu live USB it still fails at the grub2 install. also gparted doesnt have the same choices that Ubuntu install has when creating partitions, causing it to not recognize that i already had a root, or an EFI directory or it sometimes couldnt tell what the format of the partition was...all very annoying the reason i cant connect to internet (and cant upload the error logs) is the nuc only has Ethernet and the location i have to set up is too far away from modem. i can not move the monitor closer to modem as it is a 50inch LCD. I just want to do a basic install with one user acct and remote desktop (vnc) turned on so i can move the NUC to the modem connect via ethernet and then finish setting it up via Remote desktop/VNC chicken from my mac. While i await any assistance you maybe able to provide i am going to attempt to switch to the 32bit version and legacy boot to see if that can load grub. thnx again to anyone that can come up with a possible solution. i would love to hit "erase and install ubuntu" if anyone can figure out what is stopping that simple answer from working. Also disks (CD/DVD) are not an option as neither my Mac mini or my NUC have optical drives, and i have no desire to buy one for one task

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  • Informed TDD &ndash; Kata &ldquo;To Roman Numerals&rdquo;

    - by Ralf Westphal
    Originally posted on: http://geekswithblogs.net/theArchitectsNapkin/archive/2014/05/28/informed-tdd-ndash-kata-ldquoto-roman-numeralsrdquo.aspxIn a comment on my article on what I call Informed TDD (ITDD) reader gustav asked how this approach would apply to the kata “To Roman Numerals”. And whether ITDD wasn´t a violation of TDD´s principle of leaving out “advanced topics like mocks”. I like to respond with this article to his questions. There´s more to say than fits into a commentary. Mocks and TDD I don´t see in how far TDD is avoiding or opposed to mocks. TDD and mocks are orthogonal. TDD is about pocess, mocks are about structure and costs. Maybe by moving forward in tiny red+green+refactor steps less need arises for mocks. But then… if the functionality you need to implement requires “expensive” resource access you can´t avoid using mocks. Because you don´t want to constantly run all your tests against the real resource. True, in ITDD mocks seem to be in almost inflationary use. That´s not what you usually see in TDD demonstrations. However, there´s a reason for that as I tried to explain. I don´t use mocks as proxies for “expensive” resource. Rather they are stand-ins for functionality not yet implemented. They allow me to get a test green on a high level of abstraction. That way I can move forward in a top-down fashion. But if you think of mocks as “advanced” or if you don´t want to use a tool like JustMock, then you don´t need to use mocks. You just need to stand the sight of red tests for a little longer ;-) Let me show you what I mean by that by doing a kata. ITDD for “To Roman Numerals” gustav asked for the kata “To Roman Numerals”. I won´t explain the requirements again. You can find descriptions and TDD demonstrations all over the internet, like this one from Corey Haines. Now here is, how I would do this kata differently. 1. Analyse A demonstration of TDD should never skip the analysis phase. It should be made explicit. The requirements should be formalized and acceptance test cases should be compiled. “Formalization” in this case to me means describing the API of the required functionality. “[D]esign a program to work with Roman numerals” like written in this “requirement document” is not enough to start software development. Coding should only begin, if the interface between the “system under development” and its context is clear. If this interface is not readily recognizable from the requirements, it has to be developed first. Exploration of interface alternatives might be in order. It might be necessary to show several interface mock-ups to the customer – even if that´s you fellow developer. Designing the interface is a task of it´s own. It should not be mixed with implementing the required functionality behind the interface. Unfortunately, though, this happens quite often in TDD demonstrations. TDD is used to explore the API and implement it at the same time. To me that´s a violation of the Single Responsibility Principle (SRP) which not only should hold for software functional units but also for tasks or activities. In the case of this kata the API fortunately is obvious. Just one function is needed: string ToRoman(int arabic). And it lives in a class ArabicRomanConversions. Now what about acceptance test cases? There are hardly any stated in the kata descriptions. Roman numerals are explained, but no specific test cases from the point of view of a customer. So I just “invent” some acceptance test cases by picking roman numerals from a wikipedia article. They are supposed to be just “typical examples” without special meaning. Given the acceptance test cases I then try to develop an understanding of the problem domain. I´ll spare you that. The domain is trivial and is explain in almost all kata descriptions. How roman numerals are built is not difficult to understand. What´s more difficult, though, might be to find an efficient solution to convert into them automatically. 2. Solve The usual TDD demonstration skips a solution finding phase. Like the interface exploration it´s mixed in with the implementation. But I don´t think this is how it should be done. I even think this is not how it really works for the people demonstrating TDD. They´re simplifying their true software development process because they want to show a streamlined TDD process. I doubt this is helping anybody. Before you code you better have a plan what to code. This does not mean you have to do “Big Design Up-Front”. It just means: Have a clear picture of the logical solution in your head before you start to build a physical solution (code). Evidently such a solution can only be as good as your understanding of the problem. If that´s limited your solution will be limited, too. Fortunately, in the case of this kata your understanding does not need to be limited. Thus the logical solution does not need to be limited or preliminary or tentative. That does not mean you need to know every line of code in advance. It just means you know the rough structure of your implementation beforehand. Because it should mirror the process described by the logical or conceptual solution. Here´s my solution approach: The arabic “encoding” of numbers represents them as an ordered set of powers of 10. Each digit is a factor to multiply a power of ten with. The “encoding” 123 is the short form for a set like this: {1*10^2, 2*10^1, 3*10^0}. And the number is the sum of the set members. The roman “encoding” is different. There is no base (like 10 for arabic numbers), there are just digits of different value, and they have to be written in descending order. The “encoding” XVI is short for [10, 5, 1]. And the number is still the sum of the members of this list. The roman “encoding” thus is simpler than the arabic. Each “digit” can be taken at face value. No multiplication with a base required. But what about IV which looks like a contradiction to the above rule? It is not – if you accept roman “digits” not to be limited to be single characters only. Usually I, V, X, L, C, D, M are viewed as “digits”, and IV, IX etc. are viewed as nuisances preventing a simple solution. All looks different, though, once IV, IX etc. are taken as “digits”. Then MCMLIV is just a sum: M+CM+L+IV which is 1000+900+50+4. Whereas before it would have been understood as M-C+M+L-I+V – which is more difficult because here some “digits” get subtracted. Here´s the list of roman “digits” with their values: {1, I}, {4, IV}, {5, V}, {9, IX}, {10, X}, {40, XL}, {50, L}, {90, XC}, {100, C}, {400, CD}, {500, D}, {900, CM}, {1000, M} Since I take IV, IX etc. as “digits” translating an arabic number becomes trivial. I just need to find the values of the roman “digits” making up the number, e.g. 1954 is made up of 1000, 900, 50, and 4. I call those “digits” factors. If I move from the highest factor (M=1000) to the lowest (I=1) then translation is a two phase process: Find all the factors Translate the factors found Compile the roman representation Translation is just a look-up. Finding, though, needs some calculation: Find the highest remaining factor fitting in the value Remember and subtract it from the value Repeat with remaining value and remaining factors Please note: This is just an algorithm. It´s not code, even though it might be close. Being so close to code in my solution approach is due to the triviality of the problem. In more realistic examples the conceptual solution would be on a higher level of abstraction. With this solution in hand I finally can do what TDD advocates: find and prioritize test cases. As I can see from the small process description above, there are two aspects to test: Test the translation Test the compilation Test finding the factors Testing the translation primarily means to check if the map of factors and digits is comprehensive. That´s simple, even though it might be tedious. Testing the compilation is trivial. Testing factor finding, though, is a tad more complicated. I can think of several steps: First check, if an arabic number equal to a factor is processed correctly (e.g. 1000=M). Then check if an arabic number consisting of two consecutive factors (e.g. 1900=[M,CM]) is processed correctly. Then check, if a number consisting of the same factor twice is processed correctly (e.g. 2000=[M,M]). Finally check, if an arabic number consisting of non-consecutive factors (e.g. 1400=[M,CD]) is processed correctly. I feel I can start an implementation now. If something becomes more complicated than expected I can slow down and repeat this process. 3. Implement First I write a test for the acceptance test cases. It´s red because there´s no implementation even of the API. That´s in conformance with “TDD lore”, I´d say: Next I implement the API: The acceptance test now is formally correct, but still red of course. This will not change even now that I zoom in. Because my goal is not to most quickly satisfy these tests, but to implement my solution in a stepwise manner. That I do by “faking” it: I just “assume” three functions to represent the transformation process of my solution: My hypothesis is that those three functions in conjunction produce correct results on the API-level. I just have to implement them correctly. That´s what I´m trying now – one by one. I start with a simple “detail function”: Translate(). And I start with all the test cases in the obvious equivalence partition: As you can see I dare to test a private method. Yes. That´s a white box test. But as you´ll see it won´t make my tests brittle. It serves a purpose right here and now: it lets me focus on getting one aspect of my solution right. Here´s the implementation to satisfy the test: It´s as simple as possible. Right how TDD wants me to do it: KISS. Now for the second equivalence partition: translating multiple factors. (It´a pattern: if you need to do something repeatedly separate the tests for doing it once and doing it multiple times.) In this partition I just need a single test case, I guess. Stepping up from a single translation to multiple translations is no rocket science: Usually I would have implemented the final code right away. Splitting it in two steps is just for “educational purposes” here. How small your implementation steps are is a matter of your programming competency. Some “see” the final code right away before their mental eye – others need to work their way towards it. Having two tests I find more important. Now for the next low hanging fruit: compilation. It´s even simpler than translation. A single test is enough, I guess. And normally I would not even have bothered to write that one, because the implementation is so simple. I don´t need to test .NET framework functionality. But again: if it serves the educational purpose… Finally the most complicated part of the solution: finding the factors. There are several equivalence partitions. But still I decide to write just a single test, since the structure of the test data is the same for all partitions: Again, I´m faking the implementation first: I focus on just the first test case. No looping yet. Faking lets me stay on a high level of abstraction. I can write down the implementation of the solution without bothering myself with details of how to actually accomplish the feat. That´s left for a drill down with a test of the fake function: There are two main equivalence partitions, I guess: either the first factor is appropriate or some next. The implementation seems easy. Both test cases are green. (Of course this only works on the premise that there´s always a matching factor. Which is the case since the smallest factor is 1.) And the first of the equivalence partitions on the higher level also is satisfied: Great, I can move on. Now for more than a single factor: Interestingly not just one test becomes green now, but all of them. Great! You might say, then I must have done not the simplest thing possible. And I would reply: I don´t care. I did the most obvious thing. But I also find this loop very simple. Even simpler than a recursion of which I had thought briefly during the problem solving phase. And by the way: Also the acceptance tests went green: Mission accomplished. At least functionality wise. Now I´ve to tidy up things a bit. TDD calls for refactoring. Not uch refactoring is needed, because I wrote the code in top-down fashion. I faked it until I made it. I endured red tests on higher levels while lower levels weren´t perfected yet. But this way I saved myself from refactoring tediousness. At the end, though, some refactoring is required. But maybe in a different way than you would expect. That´s why I rather call it “cleanup”. First I remove duplication. There are two places where factors are defined: in Translate() and in Find_factors(). So I factor the map out into a class constant. Which leads to a small conversion in Find_factors(): And now for the big cleanup: I remove all tests of private methods. They are scaffolding tests to me. They only have temporary value. They are brittle. Only acceptance tests need to remain. However, I carry over the single “digit” tests from Translate() to the acceptance test. I find them valuable to keep, since the other acceptance tests only exercise a subset of all roman “digits”. This then is my final test class: And this is the final production code: Test coverage as reported by NCrunch is 100%: Reflexion Is this the smallest possible code base for this kata? Sure not. You´ll find more concise solutions on the internet. But LOC are of relatively little concern – as long as I can understand the code quickly. So called “elegant” code, however, often is not easy to understand. The same goes for KISS code – especially if left unrefactored, as it is often the case. That´s why I progressed from requirements to final code the way I did. I first understood and solved the problem on a conceptual level. Then I implemented it top down according to my design. I also could have implemented it bottom-up, since I knew some bottom of the solution. That´s the leaves of the functional decomposition tree. Where things became fuzzy, since the design did not cover any more details as with Find_factors(), I repeated the process in the small, so to speak: fake some top level, endure red high level tests, while first solving a simpler problem. Using scaffolding tests (to be thrown away at the end) brought two advantages: Encapsulation of the implementation details was not compromised. Naturally private methods could stay private. I did not need to make them internal or public just to be able to test them. I was able to write focused tests for small aspects of the solution. No need to test everything through the solution root, the API. The bottom line thus for me is: Informed TDD produces cleaner code in a systematic way. It conforms to core principles of programming: Single Responsibility Principle and/or Separation of Concerns. Distinct roles in development – being a researcher, being an engineer, being a craftsman – are represented as different phases. First find what, what there is. Then devise a solution. Then code the solution, manifest the solution in code. Writing tests first is a good practice. But it should not be taken dogmatic. And above all it should not be overloaded with purposes. And finally: moving from top to bottom through a design produces refactored code right away. Clean code thus almost is inevitable – and not left to a refactoring step at the end which is skipped often for different reasons.   PS: Yes, I have done this kata several times. But that has only an impact on the time needed for phases 1 and 2. I won´t skip them because of that. And there are no shortcuts during implementation because of that.

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  • Can I use VirtualBox as a sandbox for 12.04?

    - by Stephen Myall
    I am quite a cautious person though not afraid to experiment. I currently have 11.10 Unity and 12.04 Beta 2 running on different partitions (no problems). I have learned here that Unity can run in VirtuaBox. When I upgrade to 12.04 LTS later this month, I am curious to understand if I could also run 12.04 in Virtual Box for experimentation and test some things before I implement them into my system? Maybe there is a better way to achieve this, without partitioning my hard drive.

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  • Algorithm to find average position

    - by Simran kaur
    In the given diagram, I have the extreme left and right points, that is -2 and 4 in this case. So, obviously, I can calculate the width which is 6 in this case. What we know: The number of partitions:3 in this case The partition number at at any point i.e which one is 1st,second or third partition (numbered starting from left) What I want: The position of the purple line drawn which is positio of average of a particular partition So, basically I just want a generalized formula to calculate position of the average at any point.

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  • Oracle Magazine, March/April 2010

    Oracle Magazine March/April features articles on enterprise software applications, application grid architecture, partitions, Tom Kyte on Edition-Based Redefinition, Oracle Application Express and much more.

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  • How do I restrict concurrent statistics gathering to a small set of tables from a single schema?

    - by Maria Colgan
    I got an interesting question from one of my colleagues in the performance team last week about how to restrict a concurrent statistics gather to a small subset of tables from one schema, rather than the entire schema. I thought I would share the solution we came up with because it was rather elegant, and took advantage of concurrent statistics gathering, incremental statistics, and the not so well known “obj_filter_list” parameter in DBMS_STATS.GATHER_SCHEMA_STATS procedure. You should note that the solution outline below with “obj_filter_list” still applies, even when concurrent statistics gathering and/or incremental statistics gathering is disabled. The reason my colleague had asked the question in the first place was because he wanted to enable incremental statistics for 5 large partitioned tables in one schema. The first time you gather statistics after you enable incremental statistics on a table, you have to gather statistics for all of the existing partitions so that a synopsis may be created for them. If the partitioned table in question is large and contains a lot of partition, this could take a considerable amount of time. Since my colleague only had the Exadata environment at his disposal overnight, he wanted to re-gather statistics on 5 partition tables as quickly as possible to ensure that it all finished before morning. Prior to Oracle Database 11g Release 2, the only way to do this would have been to write a script with an individual DBMS_STATS.GATHER_TABLE_STATS command for each partition, in each of the 5 tables, as well as another one to gather global statistics on the table. Then, run each script in a separate session and manually manage how many of this session could run concurrently. Since each table has over one thousand partitions that would definitely be a daunting task and would most likely keep my colleague up all night! In Oracle Database 11g Release 2 we can take advantage of concurrent statistics gathering, which enables us to gather statistics on multiple tables in a schema (or database), and multiple (sub)partitions within a table concurrently. By using concurrent statistics gathering we no longer have to run individual statistics gathering commands for each partition. Oracle will automatically create a statistics gathering job for each partition, and one for the global statistics on each partitioned table. With the use of concurrent statistics, our script can now be simplified to just five DBMS_STATS.GATHER_TABLE_STATS commands, one for each table. This approach would work just fine but we really wanted to get this down to just one command. So how can we do that? You may be wondering why we didn’t just use the DBMS_STATS.GATHER_SCHEMA_STATS procedure with the OPTION parameter set to ‘GATHER STALE’. Unfortunately the statistics on the 5 partitioned tables were not stale and enabling incremental statistics does not mark the existing statistics stale. Plus how would we limit the schema statistics gather to just the 5 partitioned tables? So we went to ask one of the statistics developers if there was an alternative way. The developer told us the advantage of the “obj_filter_list” parameter in DBMS_STATS.GATHER_SCHEMA_STATS procedure. The “obj_filter_list” parameter allows you to specify a list of objects that you want to gather statistics on within a schema or database. The parameter takes a collection of type DBMS_STATS.OBJECTTAB. Each entry in the collection has 5 feilds; the schema name or the object owner, the object type (i.e., ‘TABLE’ or ‘INDEX’), object name, partition name, and subpartition name. You don't have to specify all five fields for each entry. Empty fields in an entry are treated as if it is a wildcard field (similar to ‘*’ character in LIKE predicates). Each entry corresponds to one set of filter conditions on the objects. If you have more than one entry, an object is qualified for statistics gathering as long as it satisfies the filter conditions in one entry. You first must create the collection of objects, and then gather statistics for the specified collection. It’s probably easier to explain this with an example. I’m using the SH sample schema but needed a couple of additional partitioned table tables to get recreate my colleagues scenario of 5 partitioned tables. So I created SALES2, SALES3, and COSTS2 as copies of the SALES and COSTS table respectively (setup.sql). I also deleted statistics on all of the tables in the SH schema beforehand to more easily demonstrate our approach. Step 0. Delete the statistics on the tables in the SH schema. Step 1. Enable concurrent statistics gathering. Remember, this has to be done at the global level. Step 2. Enable incremental statistics for the 5 partitioned tables. Step 3. Create the DBMS_STATS.OBJECTTAB and pass it to the DBMS_STATS.GATHER_SCHEMA_STATS command. Here, you will notice that we defined two variables of DBMS_STATS.OBJECTTAB type. The first, filter_lst, will be used to pass the list of tables we want to gather statistics on, and will be the value passed to the obj_filter_list parameter. The second, obj_lst, will be used to capture the list of tables that have had statistics gathered on them by this command, and will be the value passed to the objlist parameter. In Oracle Database 11g Release 2, you need to specify the objlist parameter in order to get the obj_filter_list parameter to work correctly due to bug 14539274. Will also needed to define the number of objects we would supply in the obj_filter_list. In our case we ere specifying 5 tables (filter_lst.extend(5)). Finally, we need to specify the owner name and object name for each of the objects in the list. Once the list definition is complete we can issue the DBMS_STATS.GATHER_SCHEMA_STATS command. Step 4. Confirm statistics were gathered on the 5 partitioned tables. Here are a couple of other things to keep in mind when specifying the entries for the  obj_filter_list parameter. If a field in the entry is empty, i.e., null, it means there is no condition on this field. In the above example , suppose you remove the statement Obj_filter_lst(1).ownname := ‘SH’; You will get the same result since when you have specified gather_schema_stats so there is no need to further specify ownname in the obj_filter_lst. All of the names in the entry are normalized, i.e., uppercased if they are not double quoted. So in the above example, it is OK to use Obj_filter_lst(1).objname := ‘sales’;. However if you have a table called ‘MyTab’ instead of ‘MYTAB’, then you need to specify Obj_filter_lst(1).objname := ‘”MyTab”’; As I said before, although we have illustrated the usage of the obj_filter_list parameter for partitioned tables, with concurrent and incremental statistics gathering turned on, the obj_filter_list parameter is generally applicable to any gather_database_stats, gather_dictionary_stats and gather_schema_stats command. You can get a copy of the script I used to generate this post here. +Maria Colgan

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  • How to move Ubuntu to an SSD

    - by Bart van Heukelom
    My current situation is: One hard disk Dual boot Ubuntu 11.04 and Windows 7. Partitions: 100MB Windows System thingy 144GB Main Windows 160GB Ubuntu 4GB Swap 12GB System Restore stuff Now I want to install an 80GB SSD and move Ubuntu to it. AFAIK I need to: Shrink the 160GB Ubuntu partition to 80GB Copy it over to the SSD Change fstab to mount the SSD as / How do I do the second? And what do I need to do about Grub?

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  • Impossible to install Ubuntu 10.10 dual boot with Windows 7 on new Acer desktop computer

    - by Don Myers
    My brother has a brand new Acer Desktop with Windows 7. I have done many installs (40+) of Ubuntu starting with 8.10, and have never run into this. I've spent three hours trying to do a dual boot install of 10.10. When you get to the place where you normally would choose to install as a dual boot or overwrite the existing information on the hard drive, that block is just blank. Nothing. No choices even to do a manual partition setup. If you try to go on you get the message "No root file system is defined. Please correct this from the partitioning menu." but there is nothing in the partitioning menu. I tried a good 10.04 disc also. Same thing happens with it. I ran a gparted live cd, and it shows the hard drive as sda with 3 partitions on the original. sda1 is a small partition called PQService. sda2 is another small partition called System Reserved, and GParted says it is the boot partition. sda3 is the main partation with the operating system (Windows 7) and all of the empty space. There is a little unallocated space at the very beginning and very end of the hard drive. If I go to places in the Live CD, it shows a 640 gb hard disk called Acer, but it also shows a 640 gb hard disk called system reserved. They are the same disk. There is just one hard drive. If you click properties in the System Reserved 640 gb, it shows all information as unknown. I had to change the boot order in the bios in order to run the live cd. The hard drive instead of being listed as such is listed as Raid:Raid Ready. Something the way this computer is set up is preventing Ubuntu from being able to identify the hard drive partitions at all to do an install, even if you were not doing a dual boot and just wanted to overwrite Windows. Is this a bug that needs reported? This is a major problem for me and my brother, but also for Ubuntu if new users want to Ubuntu and find they cannot install it.

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  • How to create a recovery partition in memory

    - by Luis Alvarado
    How can I create a recovery partition in memory as an option when booting the PC so that I can check all partitions including the system one that typically loads Ubuntu. This way I can fsck for example the partition that is normally running Ubuntu but without having it running it at that moment. The recovery partition would have access to some tools to check the disck, memory, etc. Is this doable?

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  • Installing Windows 8 over 12.04, but getting "error: unknown filesystem"

    - by Shane O'Connor
    I have had bad experiences with 12.04 on my laptop, too many things just dont work so am wiping it and replacing with Windows 8 release preview to get it running again. Anyway, I installed normally, deleted partitions and formatted and installed windows fine, but now there is an error coming up when it boots: error: unknown filesystem grub rescue Ive tried repairing from Windows 8 disk, doing FixMbr and FixBoot but hasnt worked, neither has reinstalling. Any ideas how to get rid of this?

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  • Best Settings for Ubuntu Installation

    - by Umair Mustafa
    I need to install ubuntu 12.04 as i messed up my OS. So can someone please suggest what are the best settings for Partitions. I mean should I install the Ubuntu on simple one partition. Because in this case I guess I have to install all the packages/applications everytime I install the fresh OS which is a headache. Is there a way that I can retain all the applications on New installed OS ???? My HDD size is 120 GB

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  • Need help to install Ubuntu on Win7 Alienware M17xR3, installing not working

    - by Rodrigo
    Please I need help to install linux on my computer to start analyzing Next Generation Sequencing (molecular genetics) for my work. I've tried to install from all different ways and forms and it gave me different errors. First I will describe my system: Alienware M17x R3 Raid Drive 596GB (2x 298 GB) Windows7 primary partition C: The hardrive is divided in 3 primary partitions (can't do 4 don't know why) 1st: Fat16 no name capacity 40mbs almost not used (has files like command.com, dellbio.bin, dellrmk.bin and oobedone.flg) I dont know what this is for but is blocked and non system (Status:none). 2nd: Recovery NTFS 9GB (Status:system) and it seems to have boot files. 3rd: CD: Windos OS (status:boot). And I have 2 Logical drivers F: data for backup and games :D (300gb) G: For trying to install the Linux (Already tried with Fat32, Ext2, ext3 and ext4) Installing with Wubi on F: and G: Instalation looks good on windows ask to restart dos mode appears: try (HD0,0) non-ms:skip try (HD0,1) NTFS5: No Wibildr try (HD0,2) NTFS5: Error: "Prefix" is not set. Installing with Wubi on C: Installation looks good on windows ask to restart dos mode apears: Mount denied becouse NTFS volume is already exclusive opened, the volume may be already mounted or another software may use it which could be identified for example by the help of the 'FUSER' command Mount devdm-4 Could not find installation files /ubuntu/install custom-installation Run 'Chkdsk /r' on windows and restart...blablablalba... that should correct. done this didn't work. Tried installing with USB drive and after burning a CD with the Iso file download from the official website: I've tried the option to install along windows with a G: drive in FAT32, EXT2,3 and 4, I've tried to leave unallocated data, without the driver G at all... appears this everytime: http://i.stack.imgur.com/eo2Ie.png pres ok it ask me to: Not possible to install the boot loader at the location: specify new location: I've tried to select all the drivers non is accepted If I ask to continue without installing the boot loader he ask me to install later by myself which I'm trying to figure it out but I'm not really good to understand how ppl get to the programming part like a DOS to write down couse I'm a newb and I've dont work on dos or linux before... I've read that the boot loader has to be installed on the primary partition, but I'm not sure what I can delete from those 2 partitions that would let me get 1 extra... and it seems that the one that windows use is protected to write down so the software is not touching it... Please if someone have any idea to help me out... I've got a course tomorrow of how to use the software to analyze the data and I wanted to take my computer with me, so I've passed the last 3 days trying to search different ways to solve. My question is also post on the bugs.launchpad.net link here: lounchpad.net bug #882695

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  • dual boot missing files on ntfs

    - by yehuda
    I have 3 partitions: one for win7 (ntfs), one for Ubuntu (ext4) and one just for data (ntfs so both operating systems can see them). My problem is that I had stored some files on the data partition using ubuntu and when i booted win7 all that data was gone! After that I couldn't find the files even when using Ubuntu. My files were simply GONE :( Is there something I can do in Ubuntu or is it just windows problem?

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  • WAIT-VHUB ? Whats Going On ?

    - by Neeraj Gupta
    I know many of you have been working on Oracle's Exalogic and other Engineered Systems. With partitions enabled now, things have gone multi dimension. But its fun. Isn't it ? While you have some EoIB configurations together with InfiniBand partitions, the VNICs are not coming up and staying in WAIT-VHUB state ?  Chances are that you have forgot to add InfiniBand Gateway switches' Bridge-X port GUIDs to your partition. These must be added as FULL members for EoIB to work properly. VHUB means a virtual hub in EoIB. Bridge-x is the access point for hosts to work over EoIB so thats why it must be a full member in partition. Step 1: Find out the port GUIDs of your bridge-x devices in IB Gateway switch. # showgwports INTERNAL PORTS: --------------- Device   Port Portname  PeerPort PortGUID           LID    IBState  GWState --------------------------------------------------------------------------- Bridge-0  1   Bridge-0-1    4    0x0010e00c1b60c001 0x0002 Active   Up Bridge-0  2   Bridge-0-2    3    0x0010e00c1b60c002 0x0006 Active   Up Bridge-1  1   Bridge-1-1    2    0x0010e00c1b60c041 0x0026 Active   Up Bridge-1  2   Bridge-1-2    1    0x0010e00c1b60c042 0x002a Active   Up Step 2: Add these port GUIDs to the IB partition associated with EoIB. Login to master SM switch for this task. # smpartition start # smpartition add -pkey <PKey> -port <port GUID> -m full # smpartition commit Enjoy ! 

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  • How can I solve, error:unknown filesytem grub rescue>

    - by Benson
    I was previously using Win7 and had two partitions on my hard disk. After learning about Ubuntu I decide to remove Windows and install Ubuntu 11.10 instead. All my important files and documents are stored in my second partition. After successful installation, during restart I get the error : error: unknown filesystem grub rescue> Please help me to resolve the problem, and note that I don't want dual boot my machine.

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  • Oracle Partner Tier1, inc. Launches the Tier1 Private Oracle Cloud

    - by Catalin Teodor
    Tier1, Inc. announced the availability of the Tier1 Private Oracle Cloud, the most optimized and protected computing environment for Oracle Applications and databases. Leveraging Oracle's Virtual Compute Appliance (VCA) technology, it’s the only virtual environment certified to use Oracle Trusted Partitions – the Tier1 Private Cloud provides the flexibility to license Oracle software on a virtual CPU basis. Read more!

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  • Idera SQL Doctor 3.0 and MS SQL Changes

    New features worth mentioning in SQL doctor 3.0 begin with a new server dashboard that not only gives a comprehensive overview of a SQL Server instance's current health, but also several key details to help database administrators. Some of the details include recommendations on how to optimize server configuration, how to fix certain security issues, and how to get rid of performance bottlenecks. The latest version of SQL doctor also supplies users with key server information. The status of system parameters known to affect SQL Server performance, such as processes, disk partitions, cache, m...

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  • Grub rescue - error: unknown filesystem

    - by user53817
    I have a multiboot system set up. The system has three drives. Multiboot is configured with Windows XP, Windows 7, and Ubuntu - all on the first drive. I had a lot of unpartitioned space left on the drive and was reserving it for adding other OSes and for storing files there in the future. One day I went ahead and downloaded Partition Wizard and created a logical NTFS partition from within Windows 7, still some unpartitioned space left over. Everything worked fine, until I rebooted the computer a few days later. Now I'm getting: error: unknown filesystem. grub rescue First of all I was surprised not to find any kind of help command, by trying: help, ?, man, --help, -h, bash, cmd, etc. Now I'm stuck with non-bootable system. I have started researching the issue and finding that people usually recommend to boot to a Live CD and fix the issue from there. Is there a way to fix this issue from within grub rescue without the need for Live CD? UPDATE By following the steps from persist commands typed to grub rescue, I was able to boot to initramfs prompt. But not anywhere further than that. So far from reading the manual on grub rescue, I was able to see my drives and partitions using ls command. For the first hard drive I see the following: (hd0) (hd0,msdos6) (hd0,msdos5) (hd0,msdos2) (hd0,msdos1) I now know that (hd0,msdos6) contains Linux on it, since ls (hd0,msdos6)/ lists directories. Others will give "error: unknown filesystem." UPDATE 2 After the following commands I am now getting to the boot menu and can boot into Windows 7 and Ubuntu, but upon reboot I have to repeat these steps. ls ls (hd0,msdos6)/ set root=(hd0,msdos6) ls / set prefix=(hd0,msdos6)/boot/grub insmod /boot/grub/linux.mod normal UPDATE 3 Thanks Shashank Singh, with your instructions I have simplified my steps to the following. I have learned from you that I can replace msdos6 with just a 6 and that I can just do insmod normal instead of insmod /boot/grub/linux.mod. Now I just need to figure out how to save this settings from within grub itself, without booting into any OS. set root=(hd0,6) set prefix=(hd0,6)/boot/grub insmod normal normal UPDATE 4 Well, it seems like it is a requirement to boot into Linux. After booting into Ubuntu I have performed the following steps described in the manual: sudo update-grub udo grub-install /dev/sda This did not resolve the issue. I still get the grub rescue prompt. What do I need to do to permanently fix it? I have also learned that drive numbers as in hd0 need to be translated to drive letters as in /dev/sda for some commands. hd1 would be sdb, hd2 would be sdc, and so on. Partitions listed in grub as (hd0,msdos6) would be translated to /dev/sda6.

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  • Mount a LUKS partition at boot

    - by Adam Matan
    Hi, I have installed an Ubuntu machine with two encrypted LUKS partitions: one for / and one for /home. I've reinstalled the machine to upgrade to 10.04. Again, the / is installed using LUKS, and I'm able to mount the /home using: mkdir /media/home sudo cryptsetup luksOpen /dev/sda2 home sudo mount -t ext3 /dev/mapper/home /media/home The problem is, this cryptfs mapper disappears after boot, so I putting the appropriate line in fstab fails. How do I set the cryptfs to prompt for password and unlock the drive at boot? Thanks, Adam

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  • Can I install Natty alongside Maverick and retain my encrypted /home partition?

    - by Jon
    This is my partitioning scheme: 10GB partition empty -- will be installing Natty here 10GB partition containing Maverick 2GB swap partition 300GB encrypted /home partition I've had few problems in the past with having two ubuntu installs on two separate partitions, giving /home it's own partition, but I'm a little concerned since I'm now using an encrypted /home partition. Install won't try to wipe my /home if I click " encrypt home directory," will it?

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