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  • how does one _model_ data from relational databases in clojure ?

    - by sandeep
    I have asked this question on twitter as well the #clojure IRC channel, yet got no responses. There have been several articles about Clojure-for-Ruby-programmers, Clojure-for-lisp-programmers.. but what is the missing part is Clojure for ActiveRecord programmers . There have been articles about interacting with MongoDB, Redis, etc. - but these are key value stores at the end of the day. However, coming from a Rails background, we are used to thinking about databases in terms of inheritance - has_many, polymorphic, belongs_to, etc. The few articles about Clojure/Compojure + MySQL (ffclassic) - delve right into sql. Of course, it might be that an ORM induces impedence mismatch, but the fact remains that after thinking like ActiveRecord, it is very difficult to think any other way. I believe that relational DBs, lend themselves very well to the object-oriented paradigm because of them being , essentially, Sets. Stuff like activerecord is very well suited for modelling this data. For e.g. a blog - simply put class Post < ActiveRecord::Base has_many :comments end class Comment < ActiveRecord::Base belongs_to :post end How does one model this in Clojure - which is so strictly anti-OO ? Perhaps the question would have been better if it referred to all functional programming languages, but I am more interested from a Clojure standpoint (and Clojure examples)

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  • How to create view model without sorting collections in memory.

    - by Chevex
    I have a view model (below). public class TopicsViewModel { public Topic Topic { get; set; } public Reply LastReply { get; set; } } I want to populate an IQueryable<TopicsViewModel> with values from my IQueryable<Topic> collection and IQueryable<Reply> collection. I do not want to use the attached entity collection (i.e. Topic.Replies) because I only want the last reply for that topic and doing Topic.Replies.Last() loads the entire entity collection in memory and then grabs the last one in the list. I am trying to stay in IQueryable so that the query is executed in the database. I also don't want to foreach through topics and query replyRepository.Replies because looping through IQueryable<Topic> will start the lazy loading. I'd prefer to build one expression and have all the leg work done in the lower layers. I have the following: IQueryable<TopicsViewModel> topicsViewModel = from x in topicRepository.Topics from y in replyRepository.Replies where y.TopicID == x.TopicID orderby y.PostedDate ascending select new TopicsViewModel { Topic = x, LastReply = y }; But this isn't working. Any ideas how I can populate an IQueryable or IEnumerable of TopicsViewModel so that it queries the database and grabs topics and that topic's last reply? I am trying really hard to avoid grabbing all replies related to that topic. I only want to grab the last reply. Thank you for any insight you have to offer.

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  • Why represent shopping carts and order invoices differently in a domain model?

    - by Todd
    I've built some shopping cart systems in the past, but I always designed them such that the final order invoice is just a shopping cart that has been marked as "purchased". All the logic for adding/removing/changing items in a cart is also the logic for the order. All data is stored in the same tables in the database. But it seems this is not the proper way to design an e-commerce site.. Can someone explain the benefit of separating the shopping cart from invoices in the domain model? It seems to me this would lead to a lot of duplicated code, an extra set of tables in the database, and make it harder to maintain in the event the system need to start accommodating more complicated orders (like specifying selected options for an item which may or may not change the price/availability/shipping time of the order). I'm assuming I just haven't seen the light, as every book and other example I see seems to separate these two seemingly similar concerns -- but I can't find any explanation as to the benefit of doing such! It's also the case in the systems that I design that changes are often made after the initial order is confirmed. It's not uncommon for items to be removed, replaced, or added afterwards (but prior to fulfillment).

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  • Does anyone still believe in the Capability Maturity Model for Software?

    - by Ed Guiness
    Ten years ago when I first encountered the CMM for software I was, I suppose like many, struck by how accurately it seemed to describe the chaotic "level one" state of software development in many businesses, particularly with its reference to reliance on heroes. It also seemed to provide realistic guidance for an organisation to progress up the levels improving their processes. But while it seemed to provide a good model and realistic guidance for improvement, I never really witnessed an adherence to CMM having a significant positive impact on any organisation I have worked for, or with. I know of one large software consultancy that claims CMM level 5 - the highest level - when I can see first hand that their processes are as chaotic, and the quality of their software products as varied, as other, non-CMM businesses. So I'm wondering, has anyone seen a real, tangible benefit from adherence to process improvement according to CMM? And if you have seen improvement, do you think that the improvement was specifically attributable to CMM, or would an alternative approach (such as six-sigma) have been equally or more beneficial? Does anyone still believe? As an aside, for those who haven't yet seen it, check out this funny-because-its-true parody

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  • Where to translate message strings - in the view or in the model?

    - by GrGr
    We have a multilingual (PHP) application and use gettext for i18n. There are a few classes in the backend/model that return messages or message formats for printf(). We use xgettext to extract the strings that we want to translate. We apply the gettext function T_() in the frontend/view - this seems to be where it belongs. So far we kept the backend clean from T_() calls, this way we can also unit-test messages. So in the frontend we have something like echo T_($mymodel->getMessage()); or printf(T_($mymodel->getMessageFormat()), $mymodel->getValue()); This makes it impossible to apply xgettext to extract the strings, unless we put some dummy T_("my message %s to translate") call in the MyModel class. So this leads to the more general question: Do you apply translation in the backend classes, resp. where do you apply translation and how do you keep track of the strings which you have to translate? (I am aware of Question: poedit workaround for dynamic gettext.)

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  • Do the 'up to date' guarantees provided by final field in Java's memory model extend to indirect ref

    - by mattbh
    The Java language spec defines semantics of final fields in section 17.5: The usage model for final fields is a simple one. Set the final fields for an object in that object's constructor. Do not write a reference to the object being constructed in a place where another thread can see it before the object's constructor is finished. If this is followed, then when the object is seen by another thread, that thread will always see the correctly constructed version of that object's final fields. It will also see versions of any object or array referenced by those final fields that are at least as up-to-date as the final fields are. My question is - does the 'up-to-date' guarantee extend to the contents of nested arrays, and nested objects? An example scenario: Thread A constructs a HashMap of ArrayLists, then assigns the HashMap to final field 'myFinal' in an instance of class 'MyClass' Thread B sees a (non-synchronized) reference to the MyClass instance and reads 'myFinal', and accesses and reads the contents of one of the ArrayLists In this scenario, are the members of the ArrayList as seen by Thread B guaranteed to be at least as up to date as they were when MyClass's constructor completed?

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  • Rails nested attributes with a join model, where one of the models being joined is a new record

    - by gzuki
    I'm trying to build a grid, in rails, for entering data. It has rows and columns, and rows and columns are joined by cells. In my view, I need for the grid to be able to handle having 'new' rows and columns on the edge, so that if you type in them and then submit, they are automatically generated, and their shared cells are connected to them correctly. I want to be able to do this without JS. Rails nested attributes fail to handle being mapped to both a new record and a new column, they can only do one or the other. The reason is that they are a nested specifically in one of the two models, and whichever one they aren't nested in will have no id (since it doesn't exist yet), and when pushed through accepts_nested_attributes_for on the top level Grid model, they will only be bound to the new object created for whatever they were nested in. How can I handle this? Do I have to override rails handling of nested attributes? My models look like this, btw: class Grid < ActiveRecord::Base has_many :rows has_many :columns has_many :cells, :through => :rows accepts_nested_attributes_for :rows, :allow_destroy => true, :reject_if => lambda {|a| a[:description].blank? } accepts_nested_attributes_for :columns, :allow_destroy => true, :reject_if => lambda {|a| a[:description].blank? } end class Column < ActiveRecord::Base belongs_to :grid has_many :cells, :dependent => :destroy has_many :rows, :through => :grid end class Row < ActiveRecord::Base belongs_to :grid has_many :cells, :dependent => :destroy has_many :columns, :through => :grid accepts_nested_attributes_for :cells end class Cell < ActiveRecord::Base belongs_to :row belongs_to :column has_one :grid, :through => :row end

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  • How can I add two models in one form, where one model is a has_many :through?

    - by Angela
    How do I model having multiple Addresses for a Company and assign a single Address to a Contact? Contacts belong_to a Company. A Company has_many Contacts. A Company also has_many Addresses. And each Contact has_one Address. I want to be able, whenever I create a New Contact, to access all the addresses in all Contacts that belong to the Company. Here is are my Models: class Company < ActiveRecord::Base attr_accessible :name, :phone, :addresses has_many :contacts has_many :addresses, :through => :contacts end class Contact < ActiveRecord::Base attr_accessible :first_name, :last_name, :title, :phone, :fax, :email, :company, :date_entered, :campaign_id, :company_name, :address belongs_to :company has_one :address accepts_nested_attributes_for :address end class Address < ActiveRecord::Base attr_accessible :street1 has_many :contacts end How do I create the View in the _form for Contacts so that I can 1) Add an Address when creating a Contact; 2) Display the options of the Address. Here is how I am doing step 1, which is just to add a new address for a new contact: <% f.fields_for :addresses do |builder| %> <p> <%= builder.label :street1, "Street 1" %> </br> <%= builder.text_field :street1 %> <p> Right now, what I have doesn't work. The console says I cannot mass-assign addresses when I hit "submit" on this New contact form.

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  • Ruby on Rails How do I access variables of a model inside itself like in this example?

    - by banditKing
    I have a Model like so: # == Schema Information # # Table name: s3_files # # id :integer not null, primary key # owner :string(255) # notes :text # created_at :datetime not null # updated_at :datetime not null # last_accessed_by_user :string(255) # last_accessed_time_stamp :datetime # upload_file_name :string(255) # upload_content_type :string(255) # upload_file_size :integer # upload_updated_at :datetime # class S3File < ActiveRecord::Base #PaperClip methods attr_accessible :upload attr_accessor :owner Paperclip.interpolates :prefix do |attachment, style| I WOULD LIKE TO ACCESS VARIABLE= owner HERE- HOW TO DO THAT? end has_attached_file( :upload, :path => ":prefix/:basename.:extension", :storage => :s3, :s3_credentials => {:access_key_id => "ZXXX", :secret_access_key => "XXX"}, :bucket => "XXX" ) #Used to connect to users through the join table has_many :user_resource_relationships has_many :users, :through => :user_resource_relationships end Im setting this variable in the controller like so: # POST /s3_files # POST /s3_files.json def create @s3_file = S3File.new(params[:s3_file]) @s3_file.owner = current_user.email respond_to do |format| if @s3_file.save format.html { redirect_to @s3_file, notice: 'S3 file was successfully created.' } format.json { render json: @s3_file, status: :created, location: @s3_file } else format.html { render action: "new" } format.json { render json: @s3_file.errors, status: :unprocessable_entity } end end end Thanks, any help would be appreciated.

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  • An Array returned by a model association is not an Array?

    - by Warren
    We have a model association that looks something like this: class Example < ActiveRecord::Base has_many :others, :order => 'others.rank' end The rank column is an integer type. The details of these particular models are not really important though as we have found the same problem with other has_many associations between other models. We have also added to the Enumerable module: module Enumerable def method_missing(name) super unless name.to_s[0..7] == 'collect_' method = name.to_s[8..-1] collect{|element| element.send(method)} end end This adds a collect_id method that we can use to get an array of record ids from an array of ActiveRecord objects. So if we use a normal ActiveRecord find :all, we get a nice array which we can then use collect_id on but if we use Example.others.collect_id, we get NoMethodError: undefined method `collect_id' for #<Class:0x2aaaac0060a0> Example.others.class returns "Array" so is it lying or confused? Our solution thus far has been to use it this way: Example.others.to_a.collect_id This works but this seems a bit strange. Why would you have to do that? We are on Ruby 1.8.7 and Rails 2.3.4

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  • Package upgrade on Ubuntu raid server and grub setup issue

    - by RecNes
    I have remote Ubuntu 10.10 server running on raid system. I did package upgrade yesterday night for security reasons. During the upgrade, grub installation screen appeared and asked me which partition I wanted to install grub. Options are sda,sdb,md1 and md2. I decide to install them on both sda and sdb partitions. I wondering, was I make true decision? If machine get reboot is it can be boot up safely? You can find fdisk output and fstab mount points below: Fstab: proc /proc proc defaults 0 0 none /dev/pts devpts gid=5,mode=620 0 0 /dev/md0 none swap sw 0 0 /dev/md1 /boot ext3 defaults 0 0 /dev/md2 / ext3 defaults 0 0 Fdisk: Disk /dev/sda: 750.2 GB, 750156374016 bytes 255 heads, 63 sectors/track, 91201 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00029bb5 Device Boot Start End Blocks Id System /dev/sda1 1 262 2102562 fd Linux raid autodetect /dev/sda2 263 295 265072+ fd Linux raid autodetect /dev/sda3 296 91201 730202445 fd Linux raid autodetect Disk /dev/md0: 2152 MB, 2152923136 bytes 2 heads, 4 sectors/track, 525616 cylinders Units = cylinders of 8 * 512 = 4096 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000000 Disk /dev/md0 doesn't contain a valid partition table Disk /dev/md1: 271 MB, 271319040 bytes 2 heads, 4 sectors/track, 66240 cylinders Units = cylinders of 8 * 512 = 4096 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000000 Disk /dev/md1 doesn't contain a valid partition table Disk /dev/md2: 747.7 GB, 747727224832 bytes 2 heads, 4 sectors/track, 182550592 cylinders Units = cylinders of 8 * 512 = 4096 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000000 Disk /dev/md2 doesn't contain a valid partition table Disk /dev/sdb: 750.2 GB, 750156374016 bytes 255 heads, 63 sectors/track, 91201 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00088969 Device Boot Start End Blocks Id System /dev/sdb1 1 262 2102562 fd Linux raid autodetect /dev/sdb2 263 295 265072+ fd Linux raid autodetect /dev/sdb3 296 91201 730202445 fd Linux raid autodetect

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  • How to use Hardware RAID in Ubuntu Server

    - by user2071938
    I have an Adaptec RAID-Controller and created an RAID-1(Mirroring) succesfully. Now I have installed Ubuntu Server 12.04.3. When I type fdisk -l I get this output: bf@fileserver:~$ sudo fdisk -l Disk /dev/sda: 1000.2 GB, 1000204886016 bytes 255 heads, 63 sectors/track, 121601 cylinders, total 1953525168 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 4096 bytes I/O size (minimum/optimal): 4096 bytes / 4096 bytes Disk identifier: 0x00000000 Disk /dev/sda doesn't contain a valid partition table Disk /dev/sdb: 1000.2 GB, 1000204886016 bytes 255 heads, 63 sectors/track, 121601 cylinders, total 1953525168 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 4096 bytes I/O size (minimum/optimal): 4096 bytes / 4096 bytes Disk identifier: 0x00000000 Disk /dev/sdb doesn't contain a valid partition table Disk /dev/sdc: 80.0 GB, 80026361856 bytes 255 heads, 63 sectors/track, 9729 cylinders, total 156301488 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x0004c454 Device Boot Start End Blocks Id System /dev/sdc1 * 2048 499711 248832 83 Linux /dev/sdc2 501758 156301311 77899777 5 Extended /dev/sdc5 501760 156301311 77899776 8e Linux LVM Disk /dev/mapper/fileserver--vg-root: 75.6 GB, 75606523904 bytes 255 heads, 63 sectors/track, 9191 cylinders, total 147668992 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000000 Disk /dev/mapper/fileserver--vg-root doesn't contain a valid partition table Disk /dev/mapper/ddf1_Data: 1000.1 GB, 1000065728512 bytes 255 heads, 63 sectors/track, 121584 cylinders, total 1953253376 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 4096 bytes I/O size (minimum/optimal): 4096 bytes / 4096 bytes Disk identifier: 0x00000000 Disk /dev/mapper/ddf1_Data doesn't contain a valid partition table Disk /dev/mapper/fileserver--vg-swap_1: 4160 MB, 4160749568 bytes 255 heads, 63 sectors/track, 505 cylinders, total 8126464 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000000 Disk /dev/mapper/fileserver--vg-swap_1 doesn't contain a valid partition table The 80 GB HDD is for the System The 1000.2 GB HDD should be for my data. But I'm a bit confused becauser there are listed two 1000.2 GB HDDs, due the Hardware RAID shoudln't there be only one HDD vissible to the OS? (I have two 1000.2 GB HDDs in an Raid-1 Array) dmraid gives me bf@fileserver:~$ sudo dmraid -r /dev/sdb: ddf1, ".ddf1_disks", GROUP, ok, 1953253376 sectors, data@ 0 /dev/sda: ddf1, ".ddf1_disks", GROUP, ok, 1953253376 sectors, data@ 0 so It seems to be ok? But how do I partitionate this disks and which one should I mount(sdb or sda?) Hope you can help me thx Florian

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  • Merging free space of hard drive to primary partition

    - by Dibya Ranjan
    I have purchased a new HDD, I tried to format making 1 primary partition, I converted the rest unallocated space to extended partition then to logical drive now I have 3 logical drives. I feel that the size allocated to the primary partition is less so I used shrink option to the 3 logical partitions in diskmgmt but each partition is resulting in one memory block of Free space. Now I want to merge these free spaces to my primary partition.

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  • Recover RAID 5 data after created new array instead of re-using

    - by Brigadieren
    Folks please help - I am a newb with a major headache at hand (perfect storm situation). I have a 3 1tb hdd on my ubuntu 11.04 configured as software raid 5. The data had been copied weekly onto another separate off the computer hard drive until that completely failed and was thrown away. A few days back we had a power outage and after rebooting my box wouldn't mount the raid. In my infinite wisdom I entered mdadm --create -f... command instead of mdadm --assemble and didn't notice the travesty that I had done until after. It started the array degraded and proceeded with building and syncing it which took ~10 hours. After I was back I saw that that the array is successfully up and running but the raid is not I mean the individual drives are partitioned (partition type f8 ) but the md0 device is not. Realizing in horror what I have done I am trying to find some solutions. I just pray that --create didn't overwrite entire content of the hard driver. Could someone PLEASE help me out with this - the data that's on the drive is very important and unique ~10 years of photos, docs, etc. Is it possible that by specifying the participating hard drives in wrong order can make mdadm overwrite them? when I do mdadm --examine --scan I get something like ARRAY /dev/md/0 metadata=1.2 UUID=f1b4084a:720b5712:6d03b9e9:43afe51b name=<hostname>:0 Interestingly enough name used to be 'raid' and not the host hame with :0 appended. Here is the 'sanitized' config entries: DEVICE /dev/sdf1 /dev/sde1 /dev/sdd1 CREATE owner=root group=disk mode=0660 auto=yes HOMEHOST <system> MAILADDR root ARRAY /dev/md0 metadata=1.2 name=tanserv:0 UUID=f1b4084a:720b5712:6d03b9e9:43afe51b Here is the output from mdstat cat /proc/mdstat Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10] md0 : active raid5 sdd1[0] sdf1[3] sde1[1] 1953517568 blocks super 1.2 level 5, 512k chunk, algorithm 2 [3/3] [UUU] unused devices: <none> fdisk shows the following: fdisk -l Disk /dev/sda: 80.0 GB, 80026361856 bytes 255 heads, 63 sectors/track, 9729 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x000bf62e Device Boot Start End Blocks Id System /dev/sda1 * 1 9443 75846656 83 Linux /dev/sda2 9443 9730 2301953 5 Extended /dev/sda5 9443 9730 2301952 82 Linux swap / Solaris Disk /dev/sdb: 750.2 GB, 750156374016 bytes 255 heads, 63 sectors/track, 91201 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x000de8dd Device Boot Start End Blocks Id System /dev/sdb1 1 91201 732572001 8e Linux LVM Disk /dev/sdc: 500.1 GB, 500107862016 bytes 255 heads, 63 sectors/track, 60801 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00056a17 Device Boot Start End Blocks Id System /dev/sdc1 1 60801 488384001 8e Linux LVM Disk /dev/sdd: 1000.2 GB, 1000204886016 bytes 255 heads, 63 sectors/track, 121601 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x000ca948 Device Boot Start End Blocks Id System /dev/sdd1 1 121601 976760001 fd Linux raid autodetect Disk /dev/dm-0: 1250.3 GB, 1250254913536 bytes 255 heads, 63 sectors/track, 152001 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000000 Disk /dev/dm-0 doesn't contain a valid partition table Disk /dev/sde: 1000.2 GB, 1000204886016 bytes 255 heads, 63 sectors/track, 121601 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x93a66687 Device Boot Start End Blocks Id System /dev/sde1 1 121601 976760001 fd Linux raid autodetect Disk /dev/sdf: 1000.2 GB, 1000204886016 bytes 255 heads, 63 sectors/track, 121601 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0xe6edc059 Device Boot Start End Blocks Id System /dev/sdf1 1 121601 976760001 fd Linux raid autodetect Disk /dev/md0: 2000.4 GB, 2000401989632 bytes 2 heads, 4 sectors/track, 488379392 cylinders Units = cylinders of 8 * 512 = 4096 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 524288 bytes / 1048576 bytes Disk identifier: 0x00000000 Disk /dev/md0 doesn't contain a valid partition table Per suggestions I did clean up the superblocks and re-created the array with --assume-clean option but with no luck at all. Is there any tool that will help me to revive at least some of the data? Can someone tell me what and how the mdadm --create does when syncs to destroy the data so I can write a tool to un-do whatever was done? After the re-creating of the raid I run fsck.ext4 /dev/md0 and here is the output root@tanserv:/etc/mdadm# fsck.ext4 /dev/md0 e2fsck 1.41.14 (22-Dec-2010) fsck.ext4: Superblock invalid, trying backup blocks... fsck.ext4: Bad magic number in super-block while trying to open /dev/md0 The superblock could not be read or does not describe a correct ext2 filesystem. If the device is valid and it really contains an ext2 filesystem (and not swap or ufs or something else), then the superblock is corrupt, and you might try running e2fsck with an alternate superblock: e2fsck -b 8193 Per Shanes' suggestion I tried root@tanserv:/home/mushegh# mkfs.ext4 -n /dev/md0 mke2fs 1.41.14 (22-Dec-2010) Filesystem label= OS type: Linux Block size=4096 (log=2) Fragment size=4096 (log=2) Stride=128 blocks, Stripe width=256 blocks 122101760 inodes, 488379392 blocks 24418969 blocks (5.00%) reserved for the super user First data block=0 Maximum filesystem blocks=0 14905 block groups 32768 blocks per group, 32768 fragments per group 8192 inodes per group Superblock backups stored on blocks: 32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208, 4096000, 7962624, 11239424, 20480000, 23887872, 71663616, 78675968, 102400000, 214990848 and run fsck.ext4 with every backup block but all returned the following: root@tanserv:/home/mushegh# fsck.ext4 -b 214990848 /dev/md0 e2fsck 1.41.14 (22-Dec-2010) fsck.ext4: Invalid argument while trying to open /dev/md0 The superblock could not be read or does not describe a correct ext2 filesystem. If the device is valid and it really contains an ext2 filesystem (and not swap or ufs or something else), then the superblock is corrupt, and you might try running e2fsck with an alternate superblock: e2fsck -b 8193 <device> Any suggestions? Regards!

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  • Re-sizing disk partition linux/vm

    - by Tiffany Walker
    I VM Player running a linux guest and I was wanting to know how do I expand the disk? In the VM player I gave more disk space but I am not sure how to mount/expand/connect the new disk space to the system. My old disk space was 14GB [root@localhost ~]# df -h / Filesystem Size Used Avail Use% Mounted on /dev/mapper/VolGroup-lv_root 14G 4.5G 8.2G 36% / Then I expanded it and now I see sda2 which is the new space? [root@localhost ~]# fdisk -l Disk /dev/sda: 128.8 GB, 128849018880 bytes 255 heads, 63 sectors/track, 15665 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x000cd44d Device Boot Start End Blocks Id System /dev/sda1 * 1 64 512000 83 Linux Partition 1 does not end on cylinder boundary. /dev/sda2 64 2611 20458496 8e Linux LVM Disk /dev/mapper/VolGroup-lv_root: 14.5 GB, 14537457664 bytes 255 heads, 63 sectors/track, 1767 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000000 Disk /dev/mapper/VolGroup-lv_swap: 6408 MB, 6408896512 bytes 255 heads, 63 sectors/track, 779 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000000 Do I need to mount the new space first? resize2fs -p /dev/mapper/VolGroup-lv_root 108849018880 resize2fs 1.41.12 (17-May-2010) The containing partition (or device) is only 3549184 (4k) blocks. You requested a new size of 1474836480 blocks. resize2fs -p /dev/mapper/VolGroup-lv_root 128849018880 resize2fs 1.41.12 (17-May-2010) resize2fs: Invalid new size: 128849018880 [root@localhost ~]# lvextend -L+90GB /dev/mapper/VolGroup-lv_root Extending logical volume lv_root to 103.54 GiB Insufficient free space: 23040 extents needed, but only 0 available [root@localhost ~]# lvextend -L90GB /dev/mapper/VolGroup-lv_root Extending logical volume lv_root to 90.00 GiB Insufficient free space: 19574 extents needed, but only 0 available EDIT: So after trying pvcreate/vgextend nothing has so far worked. I'm guessing the new disk space added from VM Player is not showing up? pvscan PV /dev/sda2 VG VolGroup lvm2 [19.51 GiB / 0 free] Total: 1 [19.51 GiB] / in use: 1 [19.51 GiB] / in no VG: 0 [0 ]

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  • linux hardware raid 10 / lvm / virtual machine partition alignment and filesystem optimization

    - by Jason Ward
    I've been reading everything I can find about partition alignment and filesystem optimization (ext4 and xfs) but still don't know enough to be confident in setting up my current configuration. My remaining confusion comes from the LVM layer and if I should use raid parameters on the filesystem in guest os'es. My main questions are: When I use 'pvcreate --dataalignment' do I use the stripe-width as calculated for a filesystem on RAID (128kB for ext4 in my situation), the Stripe size of the RAID set (256kB), something else altogether, or do I not need this? When I create ext2/3/4 or xfs filesystems in guests on the Logical Volumes, should I add the settings for the underlying RAID (e.g. mkfs.ext4 -b 4096 -E stride=64,stripe-width=128)? Does anyone see any glaring errors in my set up below? I'm running some benchmarks now but haven't done enough to start comparing results. I have four drives in RAID 10 on a 3ware 9750-4i controller (more details on the settings below) giving me a 6.0TB device at /dev/sda. Here is my partition table: Model: LSI 9750-4i DISK (scsi) Disk /dev/sda: 5722024MiB Sector size (logical/physical): 512B/512B Partition Table: gpt Number Start End Size File system Name Flags 1 1.00MiB 257MiB 256MiB ext4 BOOTPART boot 2 257MiB 4353MiB 4096MiB linux-swap(v1) 3 4353MiB 266497MiB 262144MiB ext4 4 266497MiB 4460801MiB 4194304MiB Partition 1 is to be the /boot partition for my xen host. Partition 2 is swap. Partition 3 is to be the root (/) for my xen host. Partition 4 is to be (the only) physical volume to be used by LVM (for those who are counting, I left about 1.2TB unallocated for now) For my Xen guests, I usually create a Logical Volume of the needed size and present it to the guests for them to partition as needed. I know there are other ways of handling that but this method works best for my situation. Here's the hardware of interest on my CentOS 6.3 Xen Host: 4x Seagate Barracuda 3TB ST3000DM001 Drives (sector size: 512 logical/4096 physical) 3ware 9750-4i w/BBU (sector size reported: 512 logical/512 physical) All four drives make up a RAID 10 array. Stripe: 256kB Write Cache enabled Read Cache: intelligent StoreSave: Balance Thanks!

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  • How can I recover XFS partitions from a formatted HD?

    - by giuprivite
    I deleted the partition table of my HD. I wanted to format another one, but by mistake, I formatted the wrong one. Then I also created some new partition on it. Now I would like, if possible, to recover my old data. The old configuration was this: A primary NTFS partition with Windows, and a secondary partition with four logical partitions: a swap and three XFS partitions (two for Ubuntu and OpenSuSE, and one with the home for both systems). This is the output I get when I run gpart in a terminal: ubuntu@ubuntu:~$ sudo gpart /dev/sdb Begin scan... Possible partition(Windows NT/W2K FS), size(39997mb), offset(0mb) Possible extended partition at offset(39997mb) Possible partition(Linux swap), size(8189mb), offset(39997mb) Possible partition(SGI XFS filesystem), size(40942mb), offset(48187mb) Possible partition(SGI XFS filesystem), size(40942mb), offset(89149mb) Possible partition(SGI XFS filesystem), size(175044mb), offset(130112mb) End scan. Checking partitions... Partition(OS/2 HPFS, NTFS, QNX or Advanced UNIX): primary Partition(Linux swap or Solaris/x86): logical Partition(Linux ext2 filesystem): logical Partition(Linux ext2 filesystem): orphaned logical Partition(Linux ext2 filesystem): orphaned logical Ok. Guessed primary partition table: Primary partition(1) type: 007(0x07)(OS/2 HPFS, NTFS, QNX or Advanced UNIX) size: 39997mb #s(81915360) s(63-81915422) chs: (0/1/1)-(1023/254/63)d (0/1/1)-(5098/254/51)r Primary partition(2) type: 015(0x0F)(Extended DOS, LBA) size: 265245mb #s(543221849) s(81915435-625137283) chs: (1023/254/63)-(1023/254/63)d (5099/0/1)-(38912/254/2)r Primary partition(3) type: 000(0x00)(unused) size: 0mb #s(0) s(0-0) chs: (0/0/0)-(0/0/0)d (0/0/0)-(0/0/0)r Primary partition(4) type: 000(0x00)(unused) size: 0mb #s(0) s(0-0) chs: (0/0/0)-(0/0/0)d (0/0/0)-(0/0/0)r Looking the first eight lines, it seems the data are still there... but I don't know how to recover them. I have a free second HD of about 500 GB (the formatted one is 320 GB) that I can use for the recovery process.

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  • How can I recover XFS partitions from a formatted HD?

    - by giuprivite
    I deleted the partition table of my HD. I wanted to format another one, but by mistake, I formatted the wrong one. Then I also created some new partition on it. Now I would like, if possible, to recover my old data. The old configuration was this: A primary NTFS partition with Windows, and a secondary partition with four logical partitions: a swap and three XFS partitions (two for Ubuntu and OpenSuSE, and one with the home for both systems). This is the output I get when I run gpart in a terminal: ubuntu@ubuntu:~$ sudo gpart /dev/sdb Begin scan... Possible partition(Windows NT/W2K FS), size(39997mb), offset(0mb) Possible extended partition at offset(39997mb) Possible partition(Linux swap), size(8189mb), offset(39997mb) Possible partition(SGI XFS filesystem), size(40942mb), offset(48187mb) Possible partition(SGI XFS filesystem), size(40942mb), offset(89149mb) Possible partition(SGI XFS filesystem), size(175044mb), offset(130112mb) End scan. Checking partitions... Partition(OS/2 HPFS, NTFS, QNX or Advanced UNIX): primary Partition(Linux swap or Solaris/x86): logical Partition(Linux ext2 filesystem): logical Partition(Linux ext2 filesystem): orphaned logical Partition(Linux ext2 filesystem): orphaned logical Ok. Guessed primary partition table: Primary partition(1) type: 007(0x07)(OS/2 HPFS, NTFS, QNX or Advanced UNIX) size: 39997mb #s(81915360) s(63-81915422) chs: (0/1/1)-(1023/254/63)d (0/1/1)-(5098/254/51)r Primary partition(2) type: 015(0x0F)(Extended DOS, LBA) size: 265245mb #s(543221849) s(81915435-625137283) chs: (1023/254/63)-(1023/254/63)d (5099/0/1)-(38912/254/2)r Primary partition(3) type: 000(0x00)(unused) size: 0mb #s(0) s(0-0) chs: (0/0/0)-(0/0/0)d (0/0/0)-(0/0/0)r Primary partition(4) type: 000(0x00)(unused) size: 0mb #s(0) s(0-0) chs: (0/0/0)-(0/0/0)d (0/0/0)-(0/0/0)r Looking the first eight lines, it seems the data are still there... but I don't know how to recover them. I have a free second HD of about 500 GB (the formatted one is 320 GB) that I can use for the recovery process.

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  • How can I find a laptop if it has a different model name all over the world?

    - by Mike
    CONUNDRUM: A laptop review in the UK talks about how brilliant the "ASUS ABCDE 55" is, but in America, France, etc there is no such laptop name. In fact it's called "ASUS 12345 AB" - AAARRGH! QUESTION: Is there a way of finding out all the diverse names for the same laptop all over the world? Example: if Samsung create a R2D2500, then what is that spec laptop called in all the other countries (if they release it of course). Or if it's not released, what is their similar spec laptop called in the other countries? I understand that specs may be different, but if I read a review on my trusted UK website, but live in say Australia, I want to be able to find the name of the same laptop in Australia and then check out local places to buy it. So if anyone knows if there is a technique, specific website, or even how to use a company website to find out these annoying name changes I'd really appreciate it.

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  • Is there a CPU that can be described as "Celeron D 4xx model"?

    - by romkyns
    The "D" letter after Celeron appears to only be used for processors numbered with 3xx. Celerons of the 4xx series do not seem to have the "D". And yet I am looking at a motherboard described as supporting these processors: Intel Celeron D 3xx and 4xx models Intel Pentium 4 5xx and 6xx models Intel Pentium D 8xx and 9xx models Intel Core 2 Duo models with LGA775 Is this compatible with a Celeron 450, sSpec SLAFZ, despite not having a "D" in its name?

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  • solaris + EMC + power-path

    - by yael
    please advice - when I run powercf command on my Solaris machine , which changes this command do on the EMC storage , or on Solaris file system ? from maanual page: DESCRIPTION During system boot on Solaris hosts, the powercf utility configures PowerPath devices by scanning the HBAs for both single-ported and multiported storage system logical dev- ices. (A multiported logical device shows up on two or more HBAs with the same storage system subsystem/device identity. The identity comes from the serial number for the logical device.) For each storage system logical device found in the scan of the HBAs, powercf creates a corresponding emcpower device entry in the emcp.conf file, and it saves a primary path and an alternate primary path to that device.

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  • Automatically creating volume partitions on boot

    - by Justin Meltzer
    I followed this guide: http://www.mongodb.org/display/DOCS/Amazon+EC2+Quickstart to set up Mongodb. It had me create a RAID 10 array out of the four devices on EBS. Then it had me create a physical volume, a volume group, and three logical volumes out of that RAID 10 array. Lastly it had me create ext4 filesystems out of the logical volumes and mount them. Now the quickstart guide had me put two things in place so that these steps would be replicated on reboot of the system. It had me add some instructions to the mdadm.conf file to automatically create the RAID 10 array, and it also had me add instructions to the fstab file to automatically mount the filesystem for each logical volume. However, the quickstart guide does not have anything for automatically creating the logical volumes from the RAID 10 array. I checked my system and see that each of the four devices are part of a RAID array: $ sudo mdadm -Q /dev/sdh1 /dev/sdh1: is not an md array /dev/sdh1: device 0 in 4 device unknown raid10 array. Use mdadm --examine for more detail. However, the filesystem is never created or mounted from fstab because it's trying to mount it from logical volumes that were never created (or so it seems). My question is, how can I automatically accomplish all the steps from the quickstart guide on a reboot of the system, and what config file do I need to add data to so that I can automatically create these volume partions after the RAID 10 is created but before the filesystem is mounted. Also I'm unsure whether fstab actually creates and mounts the filesystem or just mounts the filesystem.

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