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  • Drawbacks with reading and writing a big file to or from disk at once instead of small chunks?

    - by Johann Gerell
    I work mainly on Windows and Windows CE based systems, where CreateFile, ReadFile and WriteFile are the work horses, no matter if I'm in native Win32 land or in managed .Net land. I have so far never had any obvious problem writing or reading big files in one chunk, as opposed to looping until several smaller chunks are processed. I usually delegate the IO work to a background thread that notifies me when it's done. But looking at file IO tutorials or "textbook examples", I often find the "loop with small chunks" used without any explanation of why it's used instead of the more obvious (I dare to say!) "do it all at once". Are there any drawbacks to the way I do that I haven't understood?

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  • Using Python, what's the best way to create a set of files on disk for testing?

    - by Chris R
    I'm looking for a way to create a tree of test files to unit test a packaging tool. Basically, I want to create some common file system structures -- directories, nested directories, symlinks within the selected tree, symlinks outside the tree, &c. Ideally I want to do this with as little boilerplate as possible. Of course, I could hand-write the set of files I want to see, but I'm thinking that somebody has to have automated this for a test suite somewhere. Any suggestions?

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  • Javascript: Save json data as a file on the server / user's hard disk.

    - by DavidR
    I have developed an app that allows the user to fill out text fields with information. I want them to be able to press a button that will make a file with data (a really long array with info on what they typed and where it should go) so they can reload the data at a later date. I don't have a server now, and I am sending this app as a standalone html app to my friends for their use until I get hosing / mySql / etc. Is there a way that when they click on a button it will take this data (saved as an array, save_data), put it into a file, and basically begin the download process from their web-browser? And later on, what tech would I need to be looking into to save this into online user accounts?

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  • How to read and write UTF-8 to disk on the Android?

    - by Rob Kent
    I cannot read and write extended characters (French accented characters, for example) to a text file using the standard InputStreamReader methods shown in the Android API examples. When I read back the file using: InputStreamReader tmp = new InputStreamReader(in); BufferedReader reader = new BufferedReader(tmp); String str; while ((str = reader.readLine()) != null) { ... the string read is truncated at the extended characters instead of at the end-of-line. The second half of the string then comes on the next line. I'm assuming that I need to persist my data as UTF-8 but I cannot find any examples of that, and I'm new to Java. Can anyone provide me with an example or a link to relevant documentation?

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  • What would you do if you coded a C++/OO cross-platform framework and realize its laying on your disk

    - by Manuel
    This project started as a development platform because i wanted to be able to write games for mobile devices, but also being able to run and debug the code on my desktop machine too (ie, the EPOC device emulator was so bad): the platforms it currently supports are: Window-desktop WinCE Symbian iPhone The architecture it's quite complete with 16bit 565 video framebuffer, blitters, basic raster ops, software pixel shaders, audio mixer with shaders (dsp fx), basic input, a simple virtual file system... although this thing is at it's first write and so there are places where some refactoring would be needed. Everything has been abstracted away and the guiding principle are: mostly clean code, as if it was a book to just be read object-orientation, without sacrifying performances mobile centric The idea was to open source it, but without being able to manage it, i doubt the software itself would benefit from this move.. Nevertheless, i myself have learned a lot from unmaintained projects. So, thanking you in advance for reading all this... really, what would you do?

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  • Can I compile and execute C# expression without saving the assembly to disk?

    - by Sasha
    I can compile, get an instance and invoke a method of any C# type programmaticaly. There lots of info on that, including the StackOverflow (http://stackoverflow.com/questions/53844/how-can-i-evaluate-a-c-expression-dynamically). My problem is that I'm in the web environment and cannot save anything to /bin directory. I can compile "in-memory" as the above mentioned link suggests but then I won't be able to "unload" my custom assembly from the current AppDomain. After a while that will become a huge memory problem. Is it possible to open a new AppDomain, compile new assembly "in-memory", evaluate some expression or access some member of that assembly inside of that new AppDomain and kill that AppDomain safely when done, all that without saving anything to a hard drive? Thanks in advance for any links, suggestions, etc.

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  • In OCaml, how can I create an out_channel which writes to a string/buffer instead of a file on disk

    - by Tianyi Cui
    I have a function of type in_channel -> out_channel -> unit which will output something to an out_channel. Now I'd like to get its output as a string. Creating temporary files to write and read it back seems ugly, so how can I do that? Is there any other methods to create out_channel besides Pervasives.open_out family? Actually, this function implemented a repl. What I really need is to test it programmatically, so I'd like to first wrap it to a function of type string -> string. For creating the in_channel, it seems I can use Scanf.Scanning.from_string, but I don't know how to create the out_channel parameter.

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  • Ajax image upload and javascript edit on the fly with ASP.NET MVC (without saving to disk)

    - by gavss
    1) Uploadimage action gets requests from form posts. <form action="/content/uploadimage" method="post" enctype="multipart/form-data"> It reads HttpPostedFileBase stream data and sends it to the response. I need to show the image in a div container instead of sending it to the response as a file so that users can manipulate the image using jcrop. Image source is generated at runtime. I can't pass an action name to the src attribute. Is this possible using MVC and without using control viewstate? 2) I don't want to use flash or silverlight. Is there an easy ajax alternative to the method I use to get files from user?

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  • Can you write to a file (on a disk) in JavaScript?

    - by asdfqwer
    I don't wanna come across as a troll, so please excuse my question's demeanor, but I am a novice-intermediate programmer taking a stab at AJAX. While reading up on JavaScript I found it curious that most of the examples I've been drawing on use PHP for such an operation. I know many of you may argue that 'I'm doing it wrong' or 'JavaScript is a client-side language' etc. but the question stands. . .can you write a file in only JavaScript? EDIT: Sorry, just read faq, failed to mention this my first post on Stackoverflow while I hope I'm not sounding argumentative, pompous, or subjective.

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  • DRBD not syncing between my nodes when IP is reset

    - by ramdaz
    I am trying to setup DRBD by following the article at http://www.howtoforge.com/setting-up-network-raid1-with-drbd-on-ubuntu-11.10-p2 I am using Ubuntu 10.04 DRBD - 8.3.11 In the first run I had everything working perfectly and when shifting the systems to a production environment I decided to restart the Meta Data creation part and start from scratch. The IPs had changed entirely in the production environment. Issuing drdbadm create-md r0 in both the servers runs successfully. But when I do "drbdadm -- --overwrite-data-of-peer primary all" on the primary it fails to start the re sync. My config file is as given below resource r0 { protocol C; syncer { rate 50M; } startup { wfc-timeout 15; degr-wfc-timeout 60; } net { cram-hmac-alg sha1; shared-secret "aklsadkjlhdbskjndsf8738734jkfkjfkjf"; } on primaryds { device /dev/drbd0; disk /dev/md2; address 172.16.7.1:7788; meta-disk internal; } on secondaryds { device /dev/drbd0; disk /dev/md2; address 172.16.7.3:7788; meta-disk internal; } } Status on primary root at primaryds:~# cat /proc/drbd version: 8.3.7 (api:88/proto:86-91) GIT-hash: ea9e28dbff98e331a62bcbcc63a6135808fe2917 build by root at primaryds, 2012-05-12 15:08:01 0: cs:WFBitMapS ro:Primary/Secondary ds:UpToDate/Inconsistent C r---- ns:0 nr:0 dw:0 dr:200 al:0 bm:0 lo:0 pe:0 ua:0 ap:0 ep:1 wo:b oos:5690352828 Status on secondary root at secondaryds:/etc/drbd.d# cat /proc/drbd version: 8.3.7 (api:88/proto:86-91) GIT-hash: ea9e28dbff98e331a62bcbcc63a6135808fe2917 build by root at secondaryds, 2012-05-12 15:25:25 0: cs:WFBitMapT ro:Secondary/Primary ds:Inconsistent/UpToDate C r---- ns:0 nr:0 dw:0 dr:0 al:0 bm:0 lo:0 pe:0 ua:0 ap:0 ep:1 wo:b oos:5690352828 Log of Primary May 30 13:42:23 primaryds kernel: [ 1584.057076] block drbd0: role( Secondary -> Primary ) disk( Inconsistent -> UpToDate ) May 30 13:42:23 primaryds kernel: [ 1584.086264] block drbd0: Forced to consider local data as UpToDate! May 30 13:42:23 primaryds kernel: [ 1584.086303] block drbd0: Creating new current UUID May 30 13:42:26 primaryds kernel: [ 1586.405551] block drbd0: drbd_sync_handshake: May 30 13:42:26 primaryds kernel: [ 1586.405564] block drbd0: self E8A075F378173D4B:0000000000000004:0000000000000000:0000000000000000 bits:1422588207 flags:0 May 30 13:42:26 primaryds kernel: [ 1586.405574] block drbd0: peer 0000000000000004:0000000000000000:0000000000000000:0000000000000000 bits:1422588207 flags:0 May 30 13:42:26 primaryds kernel: [ 1586.405582] block drbd0: uuid_compare()=2 by rule 30 May 30 13:42:26 primaryds kernel: [ 1586.405587] block drbd0: Becoming sync source due to disk states. May 30 13:42:26 primaryds kernel: [ 1586.405592] block drbd0: Writing the whole bitmap, full sync required after drbd_sync_handshake. May 30 13:42:27 primaryds kernel: [ 1588.171638] block drbd0: 5427 GB (1422588207 bits) marked out-of-sync by on disk bit-map. May 30 13:42:27 primaryds kernel: [ 1588.172769] block drbd0: conn( Connected -> WFBitMapS ) Log in Secondary May 30 13:42:24 secondaryds kernel: [ 1563.304894] block drbd0: peer( Secondary - Primary ) pdsk( Inconsistent - UpToDate ) May 30 13:42:24 secondaryds kernel: [ 1563.339674] block drbd0: drbd_sync_handshake: May 30 13:42:24 secondaryds kernel: [ 1563.339685] block drbd0: self 0000000000000004:0000000000000000:0000000000000000:0000000000000000 bits:1422588207 flags:0 May 30 13:42:24 secondaryds kernel: [ 1563.339695] block drbd0: peer E8A075F378173D4B:0000000000000004:0000000000000000:0000000000000000 bits:1422588207 flags:0 May 30 13:42:24 secondaryds kernel: [ 1563.339703] block drbd0: uuid_compare()=-2 by rule 20 May 30 13:42:24 secondaryds kernel: [ 1563.339709] block drbd0: Becoming sync target due to disk states. May 30 13:42:24 secondaryds kernel: [ 1563.339714] block drbd0: Writing the whole bitmap, full sync required after drbd_sync_handshake. May 30 13:42:26 secondaryds kernel: [ 1565.652342] block drbd0: 5427 GB (1422588207 bits) marked out-of-sync by on disk bit-map. May 30 13:42:26 secondaryds kernel: [ 1565.652965] block drbd0: conn( Connected - WFBitMapT ) The serves are not responding once it reaches this stage. Tried redoing it couple of time but noting happens. Why could the resync not be taking place? I would like some advice? Directions?

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  • How do I reset/update my BIOS for Optiplex GX280?

    - by Sam Langlhey
    So far this has been a nightmare for me, which has been frustrating me constantly. I am using Dell Optiplex GX280 with Windows XP home edition, which is running a BIOS version A04. Recently, i've rebooted the pc to find out that its not booting. It will get to the Windows boot up screen with the progress bar but only to restart to the same process again, over and over. Frustrated that I am, i've inserted the Windows recovery CD to at least either repair of reinstall the operating system to find out that was not possible. I hit F8 to have the boot options, each of the boot option that I've selected gave me an error saying: "Selected boot device is not available." Right after that, I went to the BIOS setting and did a diagnostic test, which recognized all the Boot devices onboard. Now, I cannot even repair of reinstall Windows XP, because the system is not booting from none of the boot devices. The surprise is when I removed the hard-drive from the computer and loaded it on into another computer successfully; that's right, there is nothing wrong with the hard drive. After that I was totally puzzled. I found a few pointers online saying that the BIOS start-up block might be corrupted itself and I might need to flash/update the BIOS. I found the detailed instruction on how to create a Boot up disk by downloading the BIOS firmware from the manufacture's website. I did exactly as instructed below: Download the latest version or your choose version of BIOS file for your computer or motherboard from the manufacturer’s support site. Rename the downloaded file to AMIBOOT.ROM. Copy the file to a floppy disk. Insert the floppy disk to the floppy drive. Turn on the system. After I did that and powered on the PC to boot from the floppy drive, it gave me this error message: "Non-System Disk or Disk Error. Replace and Strike any key when ready." I did all that, and I kept on pressing [Ctrl]+[Home] to force it, but it did not did any satisfying result. Desperate as I am, my next attempt is to try the instruction below. Since I want to be ready, in the event it does not work, do you have any solution that you can provide? Please keep in mind that I cannot boot from any of the devices at this moment. My only hope now is to come on with a solution that will work through the Floppy drive, since that's the only drive that affected. Thank you very much for your advice and support in advance. To create a Windows startup disk, insert a floppy disk into the drive of a similarly configured, working Windows XP system, launch My Computer, right-click the floppy disk icon, and select the Format command from the context menu. When you see the Format dialog box, leave all the default settings as they are and click the Start button. Once the format operation is complete, close the Format dialog box to return to My Computer, double-click the drive C icon to access the root directory, and copy the following three files to the floppy disk: Boot.ini NTLDR Ntdetect.com

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  • Informaton of pendriver with libudv on linux

    - by Catanzaro
    I'm doing a little app in C that read the driver information of my pendrive: Plugged it and typed dmesg: [ 7676.243994] scsi 7:0:0:0: Direct-Access Lexar USB Flash Drive 1100 PQ: 0 ANSI: 0 CCS [ 7676.248359] sd 7:0:0:0: Attached scsi generic sg2 type 0 [ 7676.256733] sd 7:0:0:0: [sdb] 7831552 512-byte logical blocks: (4.00 GB/3.73 GiB) [ 7676.266559] sd 7:0:0:0: [sdb] Write Protect is off [ 7676.266566] sd 7:0:0:0: [sdb] Mode Sense: 43 00 00 00 [ 7676.266569] sd 7:0:0:0: [sdb] Assuming drive cache: write through [ 7676.285373] sd 7:0:0:0: [sdb] Assuming drive cache: write through [ 7676.285383] sdb: sdb1 [ 7676.298661] sd 7:0:0:0: [sdb] Assuming drive cache: write through [ 7676.298667] sd 7:0:0:0: [sdb] Attached SCSI removable disk with "udevadm info -q all -n /dev/sdb" P: /devices/pci0000:00/0000:00:11.0/0000:02:03.0/usb1/1-1/1-1:1.0/host7/target7:0:0/7:0:0:0/block/sdb N: sdb W: 36 S: block/8:16 S: disk/by-id/usb-Lexar_USB_Flash_Drive_AA5OCYQII8PSQXBB-0:0 S: disk/by-path/pci-0000:02:03.0-usb-0:1:1.0-scsi-0:0:0:0 E: UDEV_LOG=3 E: DEVPATH=/devices/pci0000:00/0000:00:11.0/0000:02:03.0/usb1/1-1/1-1:1.0/host7/target7:0:0/7:0:0:0/block/sdb E: MAJOR=8 E: MINOR=16 E: DEVNAME=/dev/sdb E: DEVTYPE=disk E: SUBSYSTEM=block E: ID_VENDOR=Lexar E: ID_VENDOR_ENC=Lexar\x20\x20\x20 E: ID_VENDOR_ID=05dc E: ID_MODEL=USB_Flash_Drive E: ID_MODEL_ENC=USB\x20Flash\x20Drive\x20 E: ID_MODEL_ID=a813 E: ID_REVISION=1100 E: ID_SERIAL=Lexar_USB_Flash_Drive_AA5OCYQII8PSQXBB-0:0 E: ID_SERIAL_SHORT=AA5OCYQII8PSQXBB E: ID_TYPE=disk E: ID_INSTANCE=0:0 E: ID_BUS=usb E: ID_USB_INTERFACES=:080650: E: ID_USB_INTERFACE_NUM=00 E: ID_USB_DRIVER=usb-storage E: ID_PATH=pci-0000:02:03.0-usb-0:1:1.0-scsi-0:0:0:0 E: ID_PART_TABLE_TYPE=dos E: UDISKS_PRESENTATION_NOPOLICY=0 E: UDISKS_PARTITION_TABLE=1 E: UDISKS_PARTITION_TABLE_SCHEME=mbr E: UDISKS_PARTITION_TABLE_COUNT=1 E: DEVLINKS=/dev/block/8:16 /dev/disk/by-id/usb-Lexar_USB_Flash_Drive_AA5OCYQII8PSQXBB-0:0 /dev/disk/by-path/pci-0000:02:03.0-usb-0:1:1.0-scsi-0:0:0:0 and my software is: Codice: Seleziona tutto #include <stdio.h> #include <libudev.h> #include <stdlib.h> #include <locale.h> #include <unistd.h> int main(void) { struct udev_enumerate *enumerate; struct udev_list_entry *devices, *dev_list_entry; struct udev_device *dev; /* Create the udev object */ struct udev *udev = udev_new(); if (!udev) { printf("Can't create udev\n"); exit(0); } enumerate = udev_enumerate_new(udev); udev_enumerate_add_match_subsystem(enumerate, "scsi_generic"); udev_enumerate_scan_devices(enumerate); devices = udev_enumerate_get_list_entry(enumerate); udev_list_entry_foreach(dev_list_entry, devices) { const char *path; /* Get the filename of the /sys entry for the device and create a udev_device object (dev) representing it */ path = udev_list_entry_get_name(dev_list_entry); dev = udev_device_new_from_syspath(udev, path); /* usb_device_get_devnode() returns the path to the device node itself in /dev. */ printf("Device Node Path: %s\n", udev_device_get_devnode(dev)); /* The device pointed to by dev contains information about the hidraw device. In order to get information about the USB device, get the parent device with the subsystem/devtype pair of "usb"/"usb_device". This will be several levels up the tree, but the function will find it.*/ dev = udev_device_get_parent_with_subsystem_devtype( dev, "block", "disk"); if (!dev) { printf("Errore\n"); exit(1); } /* From here, we can call get_sysattr_value() for each file in the device's /sys entry. The strings passed into these functions (idProduct, idVendor, serial, etc.) correspond directly to the files in the directory which represents the USB device. Note that USB strings are Unicode, UCS2 encoded, but the strings returned from udev_device_get_sysattr_value() are UTF-8 encoded. */ printf(" VID/PID: %s %s\n", udev_device_get_sysattr_value(dev,"idVendor"), udev_device_get_sysattr_value(dev, "idProduct")); printf(" %s\n %s\n", udev_device_get_sysattr_value(dev,"manufacturer"), udev_device_get_sysattr_value(dev,"product")); printf(" serial: %s\n", udev_device_get_sysattr_value(dev, "serial")); udev_device_unref(dev); } /* Free the enumerator object */ udev_enumerate_unref(enumerate); udev_unref(udev); return 0; } the problem is that i obtain in output: Device Node Path: /dev/sg0 Errore and dont view information. subsystem and the devtype i think that are inserted well : "block" and "disk". thanks for help. Bye

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  • Installation doesn't detect existing partitions

    - by retrac1324
    I am trying to install Ubuntu 11.10 in a dual boot with my existing Windows 7 but the installer does not detect any existing partitions. I have tried resetting my BCD using EasyBCD and doing fixmbr from the Windows startup disc. A while ago I had to use TestDisk to recover my partition table so this might be the cause but I have installed Ubuntu and Windows many times before with no problems. fdisk -l output: Disk /dev/sda: 640.1 GB, 640135028736 bytes 255 heads, 63 sectors/track, 77825 cylinders, total 1250263728 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: 0x360555e5 Device Boot Start End Blocks Id System /dev/sda1 * 2048 1250274689 625136321 7 HPFS/NTFS/exFAT Disk /dev/sdf: 7803 MB, 7803174912 bytes 255 heads, 63 sectors/track, 948 cylinders, total 15240576 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: 0x6f795a8d Device Boot Start End Blocks Id System /dev/sdf1 * 63 15240575 7620256+ c W95 FAT32 (LBA)

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  • Gnome 3 freezes on logon on samsung RV 509

    - by Noufal
    I have a Samsung NP-RV509 A0FIN and I tried to install GNU/Linux with gnome 3.2 on it. I tried Fedora 16, Ubuntu 11.10 and Linux Mint 12 RC, but with no success. All of these freezes upon login into gnome shell. I think it is the problem with graphics driver, so I tried xorg-edgers ppa on my last installation, ie., Linux Mint. I also tried various intel graphics packages listed on Synaptic package manager, but no success again. My device configuration is as follows(obtained from windows 7): More details about my computer Component Details Subscore Base score Processor Intel(R) Pentium(R) CPU P6200 @ 2.13GHz 5.6 4.6 Memory (RAM) 4.00 GB 7.2 Graphics Intel(R) HD Graphics 4.6 Gaming graphics 1562 MB Total available graphics memory 5.2 Primary hard disk 12GB Free (50GB Total) 5.9 Windows 7 Ultimate System -------------------------------------------------------------------------------- Manufacturer SAMSUNG ELECTRONICS CO., LTD. Model RV409/RV509/RV709 Total amount of system memory 4.00 GB RAM System type 32-bit operating system Number of processor cores 2 64-bit capable Yes Storage -------------------------------------------------------------------------------- Total size of hard disk(s) 418 GB Disk partition (C:) 12 GB Free (50 GB Total) Media drive (D:) CD/DVD Disk partition (E:) 526 MB Free (191 GB Total) Disk partition (F:) 101 GB Free (177 GB Total) Graphics -------------------------------------------------------------------------------- Display adapter type Intel(R) HD Graphics Total available graphics memory 1562 MB Dedicated graphics memory 64 MB Dedicated system memory 0 MB Shared system memory 1498 MB Display adapter driver version 8.15.10.2202 Primary monitor resolution 1366x768 DirectX version DirectX 10 Network -------------------------------------------------------------------------------- Network Adapter Realtek PCIe GBE Family Controller Network Adapter Broadcom 802.11n Network Adapter Network Adapter Microsoft Virtual WiFi Miniport Adapter Notes -------------------------------------------------------------------------------- The gaming graphics score is based on the primary graphics adapter. If this system has linked or multiple graphics adapters, some software applications may see additional performance benefits. Any help is appreciated, and thanks in advance.

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  • dual boot xp/xp, now win7/xp getting no xp

    - by ped
    I have a laptop on which I have two drives with separate XP installs, one barebones for music production, the other "normal" XP with Office etc. (Unfortunately the bios won't give a boot disk choice) Normally I would be presented with two WinXPs on booting. Selecting the second one would get me into the "normal installation on disk 1 (C).Selecting the first in boot order would give me D: (disk 2) withe barebones XP. However, I installed Windows 7 Home onto disk 1 (C:), but there were no dual boot options anymore, even though I installed DualBoot Pro and added WinXP disk D:. The options now show show up, but seletcing Win XP just turns into a reboot back to where I started. Any help would be much appreciated

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  • Why can't I resize some virtual thick disks in VMWhare vSphere Client

    - by Paul-Jan
    Let me start off by mentioning I am really really new to this whole VMWare ESX/vSphere thing, so apologies if this is a FAQ or asked a million times before using better wording. Also, please correct me if I'm using the wrong terms all over the place. We just got this brand new VMWare EXS server, and we started importing virtual machines from around the office. Some of them were originally based on VMWare, others are converted from MS Virtual Server. One of these machines needs a bigger disk, but in the vSphere Client the disk size spinedit is disabled. Disk type is thick. However, for other machines, with the same disk type, the spinedit is enabled and I can happily resize their disks. So here is the question: why can't I resize this disk in particular? All machines are freshly converted, so I assume there are no snapshots yet, which I read would stop a resize from happening (again, correct me if I'm wrong).

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  • Begin the Clone Wars Have!

    - by Antony Reynolds
    Creating a New Virtual Machine from an Existing Virtual Disk In previous posts I described how I set up an OEL6 machine under VirtualBox that can run an 11gR2 database and FMW 11.1.1.5.  That is great if you want the DB and FMW running in the same virtual image and it has served me well for some proof of concepts and also for some testing of different JVMs.  However I also wanted to run some testing of FMW with the database running on a separate physical machine.  So in this post I will show how to take a VirtualBox image and create a new image based on the disks from that original image. What are my Options? There is more than one way to skin a cat, or in this case to create two separate VMs that can run on different hardware.  Some of the options include: Create new virtual disk images for each new VM. Clone the existing disk images and point the new VM at the cloned images. Point the new VM at the existing snapshots. #1 is too much like hard work, install OEL twice, install a database again, install FMW again, run RCU again!  Life is too short! #2 is probably the safest way of doing things.  VirtualBox allows you to clone a disk image for use in a separate machine.  However this of course duplicates the disk and means that it is now occupying 3 times the space, once for the original disk and twice more for the two clones I would need. #3 is the most space efficient way of doing things.  It does mean however that I can only run the new “cloned” images if I have access to the original image because that is where the base snapshots reside.  However this is not a problem for me as long as I remember to keep all threee images together.  So this is the approach we will follow. Snapshot, What Snapshot? As we are going to create new virtual machines based on existing snapshots we need to figure out which snapshot to use.  We do this by opening the “Media Manager” from within VirtualBox and moving the mouse over the snapshot images until we find the snapshots we want – the snapshot name is identified in the “Attached to:” comment.  In my case I wanted the FMW installed snapshot because that had a database configured for FMW alongside the FMW software.  I made a note of the filename of that snapshot (actually I just noted the first 5 characters as that was all that was needed to uniquely identify the snapshot file). When we create the new machines we will point them at the snapshot filename we have just checked. Network or NotWork? Because we want the two new machines to communicate with each other when hosted in different physical machines we can’t use the default NAT networking mode without a lot of hassle.  But at the same time we need them to have fixed IP addresses relative to each other so that they can see each other whilst also being able to see the outside world. To achieve all these requirements I created two network adapters for each machine.  Adapter 1 was a standard NAT mapping.  This will allow each machine to get a dynamic IP address (10.0.2.15 by default) that can be used to access the external world through the VBox provided NAT gateway.  This is the same as the existing configuration. The second adapter I created as a bridged adapter.  This gives the virtual machine direct access to the host network card and by using fixed IP addresses each machine can see the other.  It is important to choose fixed IP addresses that are not routable across your internal network so you don’t get any clashes with other machines on your network.  Of course you could always get proper fixed IP addresses from your network people, but I have serveral people using my images and as long as I don’t have two instances of the same VM on the same network segment this is easier and avoids reconfiguring the network every time someone wants a copy of my VM.  If it is available I would suggest using the 10.0.3.* network as 10.0.2.* is the default NAT network.  You can check availability by pinging 10.0.3.1 and 10.0.3.2 from your host machine.  If it times out then you are probably safe to use that. Creating the New VMs Now that I had collected the data that I needed I went ahead and created the new VMs. When asked for a “Boot Hard Disk” I used the “Choose a virtual hard disk file…” link to find the snapshot I had previously selected and set that to be the existing hard disk.  I chose the previously existing SOA 11.1.1.5 install for both the new DB and FMW machines because that snapshot had the database with the RCU completed that I wanted for my DB machine and it had the SOA software installed which I wanted for my FMW machine. After the initial creation of the virtual machine go into the network setting section and enable a second adapter which will be bridged.  Make a note of the MAC addresses (the last four digits should be sufficient) of the two adapters so that you can later set the bridged adapter to use fixed IP and the NAT adapter to use DHCP. We are now ready to start the VMs and reconfigure Linux. Reconfiguring Linux Because I now have two new machines I need to change their network configuration.  In particular I need to change the hostname, update the hosts file and change the network settings. Changing the Hostname I renamed both hosts by running the hostname command as root: hostname vboxfmw.oracle.com I also edited the /etc/sysconfig file and set the correct hostname in there. HOSTNAME=vboxfmw.oracle.com Changing the Network Settings I needed to change the network configuration to give the bridged network a fixed IP address.  I first explicitly set the MAC addresses of the two adapters, because the order of the virtual adapters in the VirtualBox Manager is not necessarily the same as the order of the adapters in the guest OS.  So I went in to the System->Preferences->Network Connections screen and explicitly set the “Device MAC address” for the two adapters. Having correctly mapped the Linux adapters to the VirtualBox adapters I then set the Bridged adapter to use fixed IP addressing rather than DHCP.  There is no need for additional routing or default gateways because we expect the two machine to be on the same LAN segment. Updating the Hosts File Having renamed the machines and reconfigured the network I then updated the /etc/hosts file to refer to the new machine name add a new line to the hosts file to provide an additional IP address for my server (the new fixed IP address) add a new line for the fixed IP address of the other virtual machine 10.0.3.101      vboxdb.oracle.com       vboxdb  # Added by NetworkManager 10.0.2.15       vboxdb.oracle.com       vboxdb  # Added by NetworkManager 10.0.3.102      vboxfmw.oracle.com      vboxfmw # Added by NetworkManager 127.0.0.1       localhost.localdomain   localhost ::1     vboxdb.oracle.com       vboxdb  localhost6.localdomain6 localhost6 To make sure everything takes effect I restarted the server. Reconfiguring the Database on the DB Machine Because we changed the hostname the listener and the EM console no longer start so I need to modify the listener.ora to use the new hostname and I also need to rebuild the EM configuration because it also relies on the hostname. I edited the $ORACLE_HOME/network/admin/listener.ora and changed the listening address to the new hostname:       (ADDRESS = (PROTOCOL = TCP)(HOST = vboxdb.oracle.com)(PORT = 1521)) After changing the listener.ora I was able to start the listener using: lsnrctl start I also had to reconfigure the EM database control.  I first deconfigured it using the command: emca -deconfig dbcontrol db -repos drop This drops the repository and removes any existing registered dbcontrols. I then re-configured it using the following command: emca -config dbcontrol db -repos create This creates the EM repository and then configures and starts dbcontrol. Now my database machine is ready so I can close it down and take a snapshot. Disabling the Database on the FMW Machine I set up the database to start automatically by creating a service called “dbora”.  On the FMW machine I do not need the database running so I can prevent it auto-starting by running the following command: chkconfig –del dbora Note that because I am using a snapshot it is not a waste of disk space to have the DB installed but not used.  As long as I don’t run it, it won’t cost me anything. I can now close the FMW machine down and take a snapshot. Creating a New Domain The FMW machine is now ready to create a new domain.  When creating the domain I can point it at the second machine which is running the database.  I can potentially run these machines on two separate physical machines as long as I have the original virtual machine available to both of the physical machines. Gotchas in Snapshotting VirtualBox does not support the concept of linked machines in a network like some virtualization technologies so when creating a snapshot it is a good idea to shut both VMs down and then take a snapshot on both of them.  This is because we want to keep the database in sync with the middleware.  One way to make sure that this happens would be to place all the domain configuration files on the database server via an NFS share, this would mean that all we would need to snapshot would be the database machine because that would hold all the state and configuration. The Sky’s the Limit We have covered a simple case of having just two machines.  I have a more complicated configuration in which two machine run a RAC database off the same base OS image, and two more machines run a SOA cluster based on the same OS image.  Just remember what machine holds state and what are the consequences of taking a snapshot.

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