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• URGENT: Firefox circular-dependency hell - Linux Mint 13 (based on Ubuntu 12.04)

  - by Tyler J Fisher

  Having difficulty re-installing Firefox, after an installation to resolve places.sqlite issues. It appears that I'm trapped in circular dependency hell. Need to resolve firefox dependency hell to attempt to resolve Tomcat6 project dependencies (don't ask), ASAP. Have been trying for hours. What I've done (brief) 1) sudo apt-get purge firefox firefox-globalmenu firefox-gnome-support 2) sudo apt-get update 3) sudo apt-get install firefox firefox-globalmenu firefox-gnome-support 4) sudo apt-get -f install Potential error sources: Found in(sudo apt-get install firefox firefox-globalmenu firefox-gnome-support) dpkg: error processing /var/cache/apt/archives/firefox_18.0~a2~hg20121027r113701-0ubuntu1~umd1~precise_amd64.deb (--unpack): trying to overwrite '/usr/lib/firefox/extensions', which is also in package mint-search-addon 2012.05.11 So, /usr/lib/firefox/extensions doesn't even EXIST! Deleted /var/cache/apt/archives/firefox_18.0~a2~hg20121027r113701 as per recommendations. Errors were encountered while processing: /var/cache/apt/archives/firefox_18.0~a2~hg20121027r113701-0ubuntu1~umd1~precise_amd64.deb E: Sub-process /usr/bin/dpkg returned an error code (1) Outputs: 1) sudo apt-get purge firefox firefox-globalmenu firefox-gnome-support me@machine ~ $ sudo apt-get purge firefox-gnome-support firefox firefox-globalmenu Reading package lists... Done Building dependency tree Reading state information... Done Package firefox is not installed, so not removed The following packages will be REMOVED: firefox-globalmenu* firefox-gnome-support* 2 not fully installed or removed. 0 upgraded, 0 newly installed, 2 to remove and 38 not upgraded. After this operation, 460 kB disk space will be freed. Do you want to continue [Y/n]? y (Reading database ... dpkg: warning: files list file for package `mysqltuner' missing, assuming package has no files currently installed. (Reading database ... 192642 files and directories currently installed.) Removing firefox-globalmenu ... Removing firefox-gnome-support ... 3) me@machine ~ $ sudo apt-get install firefox firefox-globalmenu firefox-gnome-support Reading package lists... Done Building dependency tree Reading state information... Done Suggested packages: latex-xft-fonts The following NEW packages will be installed: firefox firefox-globalmenu firefox-gnome-support 0 upgraded, 3 newly installed, 0 to remove and 38 not upgraded. Need to get 0 B/24.8 MB of archives. After this operation, 54.3 MB of additional disk space will be used. (Reading database ... dpkg: warning: files list file for package `mysqltuner' missing, assuming package has no files currently installed. (Reading database ... 192619 files and directories currently installed.) Unpacking firefox (from .../firefox_18.0~a2~hg20121027r113701-0ubuntu1~umd1~precise_amd64.deb) ... dpkg: error processing /var/cache/apt/archives/firefox_18.0~a2~hg20121027r113701-0ubuntu1~umd1~precise_amd64.deb (--unpack): trying to overwrite '/usr/lib/firefox/extensions', which is also in package mint-search-addon 2012.05.11 Selecting previously unselected package firefox-globalmenu. Unpacking firefox-globalmenu (from .../firefox-globalmenu_18.0~a2~hg20121027r113701-0ubuntu1~umd1~precise_amd64.deb) ... Selecting previously unselected package firefox-gnome-support. Unpacking firefox-gnome-support (from .../firefox-gnome- support_18.0~a2~hg20121027r113701-0ubuntu1~umd1~precise_amd64.deb) ... Processing triggers for man-db ... Processing triggers for desktop-file-utils ... Processing triggers for bamfdaemon ... Rebuilding /usr/share/applications/bamf.index... Processing triggers for gnome-menus ... Processing triggers for mintsystem ... Errors were encountered while processing: /var/cache/apt/archives/firefox_18.0~a2~hg20121027r113701- 0ubuntu1~umd1~precise_amd64.deb E: Sub-process /usr/bin/dpkg returned an error code (1) 4) sudo apt-get -f install 0 upgraded, 0 newly installed, 0 to remove, and 38 not upgraded Ideas? Tomcat6 only deploys my web application successfully in Firefox, not Chrome, so I'm really hoping to resolve this dependency issue.

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• OBIEE 11.1.1 - Introduction to OBIEE 11g Full Sample App

  - by user809526

  Isn't it nice to discover OBIEE 11g around a nice "How To" catalog of features? to observe OBI and Essbase relationships at work? to discover TimesTen? The OBIEE 11g Full Sample App (FSA) is a comprehensive collection of examples designed to demonstrate the latest Oracle BIEE 11g capabilities and design best practices: Enhanced visualizations as Geo-spacial maps and interactive dashboards, Action Framework,  BI Publisher, Scorecard and Strategy Management, Mobile style sheets, Semantic layer modeling, Multi-source federation, Integration with products such as Essbase, Oracle OLAP, ODM, TimesTen, ODI and more The FSA is intended to be comprehensive, it is big (see CAVEAT below). The FSA is not an Oracle product, it is a good will free deployment of OBIEE/Essbase designed to exemplify OBIEE features, infrastructure and security around the Fusion Middleware components. Its contents and code are distributed free for demonstrative purposes only. It is neither maintained nor supported by Oracle as a licensed product. The OBIEE Full Sample App is independent of the default Sample App that comes with the OBIEE product. BENEFITS The FSA helps as a demonstrator of OBIEE 11g best practices, a tutorial, an environment "Test & Scrap", a SR bench (regression, conflicts), a tuning bench, a quick ready made POC seed for projects, a security options environment, ... The FSA - Is organized around a catalog of functional features - Has been deployed over 1000 times, it should be stable RELEASE The Full Sample App (V107) is bound to OBIEE 11.1.1.5 and Essbase 11.1.2.1 (November 2011). The FSA release dates are independent of the Product GA date (OBIEE). In early December 2011, a new functional Patch (V110) is released. It is easily applied (in less than 15 mins) on top of OBIEE SampleApp 11.1.1.5 (V107). The patch (V110) includes additional functional examples:        1. Web Catalog Statistics Application: Provides detailed insight into your web catalog content, dormant catalog objects, webcat impact analysis for metadata changes and more        2. Data inflation Scripts: A set of simple SQL procedures to quickly inflate SampleApp Fact and Dimension data to millions of records in a few minutes        3. Public Content Extensions Framework: A patching framework for public examples and contributions leveraging SampleApp        4. Additional report examples (including bridge report, external chart integrations) and bug fixes DISTRIBUTION as VBox image (November 2011) The ready made VBox image is designed to run on Virtual Box. It can be converted to VMware (see another BLOG). 1/ http://www.oracle.com/technetwork/middleware/bi-foundation/obiee-samples-167534.html VBox Image Deployment Guide Sampleapp_v107_GA.ovf - VBox image key file The above http URL provides the user:password for the ftp URLs below. 2/ ftp://user:[email protected]/static/SampleAppV107/ 12 "7-zip" files Sampleapp_v107_GA_7_20.7z.001 -> .012 We recommend 7-zip file manager for unzipping (http://www.7-zip.org/). Select Unzip here option, it will create the contents under a directory named "SampleApp_10722". On Windows, it is important to download and save zip file under the root directory (e.g. C:\ or D:\) because of possible long pathnames. 3/ ftp://user:[email protected]/static/SampleAppV107/Unzipped_Version/ 4 files Sampleapp_v107_GA-disk[1234].vmdk Important note: Check the provided checksums (md5sum). Please do it! DISTRIBUTION as Installation files for existing OBI 11.1.1.5 (November 2011) http://www.oracle.com/technetwork/middleware/bi-foundation/obiee-samples-167534.html Install files Deployment Guide SampleApp_10722_1.zip - 198 MB CAVEAT Many computers have RAM chips problems that keep often silent ... until you manipulate big files. It is strongly advised you run some memory check program eg MEMTEST in GRUB boot manager. Running md5sum repeatedly onto the very same big file must be consistent [same result], else a hardware memory problem is suspected. For Virtual Box, you should most likely enable VT-X (Vanderpool) hardware virtualization in BIOS. A free disk space of 80 GB is required to perform safely the VBox image installation. A Virtual Machine of minimum 6 to 7 GB memory fits the needs of combining OBIEE and Essbase execution.

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• Tuning Red Gate: #3 of Lots

  - by Grant Fritchey

  I'm drilling down into the metrics about SQL Server itself available to me in the Analysis tab of SQL Monitor to see what's up with our two problematic servers. In the previous post I'd noticed that rg-sql01 had quite a few CPU spikes. So one of the first things I want to check there is how much CPU is getting used by SQL Server itself. It's possible we're looking at some other process using up all the CPU Nope, It's SQL Server. I compared this to the rg-sql02 server: You can see that there is a more, consistently low set of CPU counters there. I clearly need to look at rg-sql01 and capture more specific data around the queries running on it to identify which ones are causing these CPU spikes. I always like to look at the Batch Requests/sec on a server, not because it's an indication of a problem, but because it gives you some idea of the load. Just how much is this server getting hit? Here are rg-sql01 and rg-sql02: Of the two, clearly rg-sql01 has a lot of activity. Remember though, that's all this is a measure of, activity. It doesn't suggest anything other than what it says, the number of requests coming in. But it's the kind of thing you want to know in order to understand how the system is used. Are you seeing a correlation between the number of requests and the CPU usage, or a reverse correlation, the number of requests drops as the CPU spikes? See, it's useful. Some of the details you can look at are Compilations/sec, Compilations/Batch and Recompilations/sec. These give you some idea of how the cache is getting used within the system. None of these showed anything interesting on either server. One metric that I like (even though I know it can be controversial) is the Page Life Expectancy. On the average server I expect see a series of mountains as the PLE climbs then drops due to a data load or something along those lines. That's not the case here: Those spikes back in January suggest that the servers weren't really being used much. The PLE on the rg-sql01 seems to be somewhat consistent growing to 3 hours or so then dropping, but the rg-sql02 PLE looks like it might be all over the map. Instead of continuing to look at this high level gathering data view, I'm going to drill down on rg-sql02 and see what it's done for the last week: And now we begin to see where we might have an issue. Memory on this system is getting flushed every 1/2 hour or so. I'm going to check another metric, scans: Whoa! I'm going back to the system real quick to look at some disk information again for rg-sql02. Here is the average disk queue length on the server: and the transfers Right, I think I have a guess as to what's up here. We're seeing memory get flushed constantly and we're seeing lots of scans. The disks are queuing, especially that F drive, and there are lots of requests that correspond to the scans and the memory flushes. In short, we've got queries that are scanning the data, a lot, so we either have bad queries or bad indexes. I'm going back to the server overview for rg-sql02 and check the Top 10 expensive queries. I'm modifying it to show me the last 3 days and the totals, so I'm not looking at some maintenance routine that ran 10 minutes ago and is skewing the results: OK. I need to look into these queries that are getting executed this much. They're generating a lot of reads, but which queries are generating the most reads: Ow, all still going against the same database. This is where I'm going to temporarily leave SQL Monitor. What I want to do is connect up to the server, validate that the Warehouse database is using the F:\ drive (which I'll put money down it is) and then start seeing what's up with these queries. Part 1 of the Series Part 2 of the Series

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• MP3 player mpman TS300 not recognized

  - by Nick Lemaire

  I just received a mpman ts300 mp3 player for Christmas. But when I try to connect it to ubuntu (10.10) through usb it doesn't seem to be recognized. I searched for a linuxdriver but came up with nothing. I even tried installing mpman manager from the software center, but still the same problem... Has anybody got any ideas about how to fix this? Thank you edit: some additional information When I plug it in, it doesn't show up under /dev. And it is not listed in the result of 'lsusb' This is the output of 'dmesg' [19571.732541] usb 1-4: new high speed USB device using ehci_hcd and address 2 [19571.889154] scsi7 : usb-storage 1-4:1.0 [19572.883155] scsi 7:0:0:0: Direct-Access TS300 USB DISK 1.00 PQ: 0 ANSI: 0 [19572.885856] sd 7:0:0:0: Attached scsi generic sg2 type 0 [19572.887266] sd 7:0:0:0: [sdb] 7868416 512-byte logical blocks: (4.02 GB/3.75 GiB) [19573.012547] usb 1-4: reset high speed USB device using ehci_hcd and address 2 [19573.292550] usb 1-4: reset high speed USB device using ehci_hcd and address 2 [19573.572565] usb 1-4: reset high speed USB device using ehci_hcd and address 2 [19573.725019] sd 7:0:0:0: [sdb] Test WP failed, assume Write Enabled [19573.725024] sd 7:0:0:0: [sdb] Assuming drive cache: write through [19573.728521] sd 7:0:0:0: [sdb] Attached SCSI removable disk [19575.333015] sd 7:0:0:0: [sdb] 7868416 512-byte logical blocks: (4.02 GB/3.75 GiB) [19575.452547] usb 1-4: reset high speed USB device using ehci_hcd and address 2 [19580.603253] usb 1-4: device descriptor read/all, error -110 [19580.722560] usb 1-4: reset high speed USB device using ehci_hcd and address 2 [19595.842579] usb 1-4: device descriptor read/64, error -110 [19611.072656] usb 1-4: device descriptor read/64, error -110 [19611.302540] usb 1-4: reset high speed USB device using ehci_hcd and address 2 [19616.332568] usb 1-4: device descriptor read/8, error -110 [19621.462692] usb 1-4: device descriptor read/8, error -110 [19621.692551] usb 1-4: reset high speed USB device using ehci_hcd and address 2 [19626.722567] usb 1-4: device descriptor read/8, error -110 [19631.852802] usb 1-4: device descriptor read/8, error -110 [19631.962587] usb 1-4: USB disconnect, address 2 [19631.962587] sd 7:0:0:0: Device offlined - not ready after error recovery [19631.962840] sd 7:0:0:0: [sdb] Assuming drive cache: write through [19631.965104] sd 7:0:0:0: [sdb] READ CAPACITY failed [19631.965109] sd 7:0:0:0: [sdb] Result: hostbyte=DID_NO_CONNECT driverbyte=DRIVER_OK [19631.965112] sd 7:0:0:0: [sdb] Sense not available. [19631.965125] sd 7:0:0:0: [sdb] Assuming drive cache: write through [19631.965130] sdb: detected capacity change from 4028628992 to 0 [19632.130042] usb 1-4: new high speed USB device using ehci_hcd and address 3 [19647.242550] usb 1-4: device descriptor read/64, error -110 [19662.472560] usb 1-4: device descriptor read/64, error -110 [19662.702566] usb 1-4: new high speed USB device using ehci_hcd and address 4 [19677.822587] usb 1-4: device descriptor read/64, error -110 [19693.052575] usb 1-4: device descriptor read/64, error -110 [19693.282582] usb 1-4: new high speed USB device using ehci_hcd and address 5 [19698.312600] usb 1-4: device descriptor read/8, error -110 [19703.442594] usb 1-4: device descriptor read/8, error -110 [19703.672548] usb 1-4: new high speed USB device using ehci_hcd and address 6 [19708.702581] usb 1-4: device descriptor read/8, error -110 [19713.840077] usb 1-4: device descriptor read/8, error -110 [19713.942555] hub 1-0:1.0: unable to enumerate USB device on port 4 [19714.262545] usb 4-2: new full speed USB device using uhci_hcd and address 2 [19729.382549] usb 4-2: device descriptor read/64, error -110 [19744.612534] usb 4-2: device descriptor read/64, error -110 [19744.842543] usb 4-2: new full speed USB device using uhci_hcd and address 3 [19759.962714] usb 4-2: device descriptor read/64, error -110 [19775.200047] usb 4-2: device descriptor read/64, error -110 [19775.422630] usb 4-2: new full speed USB device using uhci_hcd and address 4 [19780.444498] usb 4-2: device descriptor read/8, error -110 [19785.574491] usb 4-2: device descriptor read/8, error -110 [19785.802547] usb 4-2: new full speed USB device using uhci_hcd and address 5 [19790.824490] usb 4-2: device descriptor read/8, error -110 [19795.961473] usb 4-2: device descriptor read/8, error -110 [19796.062556] hub 4-0:1.0: unable to enumerate USB device on port 2

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• Non-standard installation (installing Linux from Linux)

  - by Evan Plaice

  So, here's my setup. I have one partition with the newest version installed, a second partition with an older version installed (as a backup just in case), a swap partition that both share, and a boot partition so the bootloader doesn't need to be setup after each upgrade. Partitions: sda1 ext3 /boot sda2 ext4 / (current version) sda3 ext4 / (old version) sda4 swap /swap sda5 ntfs (contains folders symbolically linked to /home on /) So far it has been a very good setup. I can create new boot loaders without screwing it up and adding my personal files into a new install is as simple as creating some symbolic links (the partition is NTFS in case I need to load windows on the system again). Here's the issue. I'd like to be able to drop the install into /distro on the current version and install a new version on / on the old version effectively replacing/upgrading it. The goal is to be able to just swap out new versions as they are released while maintaining redundancy in case I don't like th update. So far I have: downloaded the install.iso created a folder in /distro copied the install.iso into /distro extracted vmlinuz and initrd.lz into /distro Then I modified /boot/grub/menu.lst with the following entry: title Install Linux root (hd0,1) kernel /distro/vmlinuz initrd /distro/initrd.lz vmlinuz loads perfectly but it says it can't find initrd.lz on boot. I have also tried to uncompress the image with: unlzma < initrd.lz > initrd.img And, updating the menu.lst file to match; but that doesn't work either. I'm assuming that vmlinuz (linux kernel) loads, fires up the virtual filesystem by creating a ramdisk (initrd), mounts the iso, and launches the installer. Am I missing something here? Update: First, I wanted to say that the accepted answer would have been the best option if I was doing a normal Ubuntu install. Unfortunately, I was installing Linux Mint (which lacks the script needed to make debootstrap work. So the problem I with the above approach was, I was missing the command that vmlinuz (linux kernel) needed to execute to start boot into LiveCD mode. By looking in the /boot/grub/grub.cfg file I found what I was missing. Although this method will work, it requires that the installation files reside on their own partition. I took the easy route and used unetbootin to drop the LiveCD on a usb drive and booted from that. Like I said before. Debootstrap would have been the ideal solution here. Even though I couldn't use it I wrote down the steps it would've taken to use it. Step One: Format sda3 (the partition with the old copy of linux that's being overwritten) I used gparted to format it as ext4 from within the current linux install. How this is done varies based on what tools you prefer to use. Step Two: Mount the newly formatted partition (we'll call the mount ubuntu for simplicity) sudo mkdir /mnt/ubuntu sudo mount -o -loop /dev/sda3 /mnt/ubuntu Step Three: Get debootstrap sudo apt-get install debootstrap Step Four: Mount the install disk (replace ubuntu.iso with the name if your install disk) sudo mkdir /media/cdrom sudo mount -o loop ~/ubuntu.iso /media/cdrom Step Five: Install the OS using debootstrap (replace fiesty with the version you're installing and amd64 with your processor's architecture) sudo debootstrap --arch amd64 fiesty /mnt/ubuntu file:/media/cdrom The settings here varies. While I loaded debootstrap using an install iso, you can also have debootstrap automatically download and install if with a repository link (While most of these repositories contain debian versions I'm still not clear as to whether Ubuntu has similar repositories). Here a list of the debian package repositories and their mirrors. This is how you'd deploy debootstrap if you were doing it directly from a repository: sudo debootstrap --arch amd64 squeeze /mnt/debian http://ftp.us.debian.org/debian Here's the link that I primarily used to figure this out.

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• Removing old kernel entries in Grub

  - by To Do

  I regularly delete old kernels leaving only the latest two entries using Synaptic. I'm using Precise. However in my Grub "previous Linux version" menu there are quite a few entries labelled 2.6.8. I cannot find these linux-images in Synaptic. dpkg -l | grep linux-image Gives: rc linux-image-3.0.0-17-generic 3.0.0-17.30 Linux kernel image for version 3.0.0 on x86/x86_64 ii linux-image-3.2.0-27-generic 3.2.0-27.43 Linux kernel image for version 3.2.0 on 32 bit x86 SMP ii linux-image-3.2.0-29-generic 3.2.0-29.46 Linux kernel image for version 3.2.0 on 32 bit x86 SMP ii linux-image-3.4.0-030400-generic 3.4.0-030400.201205210521 Linux kernel image for version 3.4.0 on 32 bit x86 SMP ii linux-image-generic 3.2.0.29.31 Generic Linux kernel image Sudo update-grub gives: Generating grub.cfg ... Found linux image: /boot/vmlinuz-3.4.0-030400-generic Found initrd image: /boot/initrd.img-3.4.0-030400-generic Found linux image: /boot/vmlinuz-3.2.0-29-generic Found initrd image: /boot/initrd.img-3.2.0-29-generic Found linux image: /boot/vmlinuz-3.2.0-27-generic Found initrd image: /boot/initrd.img-3.2.0-27-generic Found linux image: /boot/vmlinuz-2.6.38-11-generic Found initrd image: /boot/initrd.img-2.6.38-11-generic Found linux image: /boot/vmlinuz-2.6.38-10-generic Found initrd image: /boot/initrd.img-2.6.38-10-generic Found linux image: /boot/vmlinuz-2.6.38-8-generic Found initrd image: /boot/initrd.img-2.6.38-8-generic Found memtest86+ image: /boot/memtest86+.bin Found Windows Vista (loader) on /dev/sda1 sudo apt-get remove linux-image-2.6.8-8-generic gives: E: Unable to locate package linux-image-2.6.8-8-generic E: Couldn't find any package by regex 'linux-image-2.6.8-8-generic' My boot folder contains the following: abi-2.6.38-10-generic initrd.img-3.4.0-030400-generic abi-2.6.38-11-generic memtest86+.bin abi-2.6.38-8-generic memtest86+_multiboot.bin abi-3.2.0-27-generic System.map-2.6.38-10-generic abi-3.2.0-29-generic System.map-2.6.38-11-generic abi-3.4.0-030400-generic System.map-2.6.38-8-generic config-2.6.38-10-generic System.map-3.2.0-27-generic config-2.6.38-11-generic System.map-3.2.0-29-generic config-2.6.38-8-generic System.map-3.4.0-030400-generic config-3.2.0-27-generic vmcoreinfo-2.6.38-10-generic config-3.2.0-29-generic vmcoreinfo-2.6.38-11-generic config-3.4.0-030400-generic vmcoreinfo-2.6.38-8-generic extlinux vmlinuz-2.6.38-10-generic grub vmlinuz-2.6.38-11-generic initrd.img-2.6.38-10-generic vmlinuz-2.6.38-8-generic initrd.img-2.6.38-11-generic vmlinuz-3.2.0-27-generic initrd.img-2.6.38-8-generic vmlinuz-3.2.0-29-generic initrd.img-3.2.0-27-generic vmlinuz-3.4.0-030400-generic initrd.img-3.2.0-29-generic and ls -l /etc/grub.d yields: total 56 -rwxr-xr-x 1 root root 6715 Apr 17 20:16 00_header -rwxr-xr-x 1 root root 5522 Oct 1 2011 05_debian_theme -rwxr-xr-x 1 root root 7407 May 17 09:22 10_linux -rwxr-xr-x 1 root root 6335 Apr 17 20:16 20_linux_xen -rwxr-xr-x 1 root root 1588 May 3 2011 20_memtest86+ -rwxr-xr-x 1 root root 7603 Apr 17 20:16 30_os-prober -rwxr-xr-x 1 root root 214 Oct 1 2011 40_custom -rwxr-xr-x 1 root root 95 Oct 1 2011 41_custom -rw-r--r-- 1 root root 483 Oct 1 2011 README gdisk -l /dev/sda yields: Partition table scan: MBR: MBR only BSD: not present APM: not present GPT: not present *************************************************************** Found invalid GPT and valid MBR; converting MBR to GPT format. *************************************************************** Disk /dev/sda: 312581808 sectors, 149.1 GiB Logical sector size: 512 bytes Disk identifier (GUID): F832A498-05E1-4615-B5B1-757ACB4A757A Partition table holds up to 128 entries First usable sector is 34, last usable sector is 312581774 Partitions will be aligned on 2048-sector boundaries Total free space is 4183661 sectors (2.0 GiB) Number Start (sector) End (sector) Size Code Name 1 2048 61442047 29.3 GiB 0700 Microsoft basic data 3 163842048 169986047 2.9 GiB 8200 Linux swap 4 169986048 312578047 68.0 GiB 0700 Microsoft basic data 5 61444096 159666175 46.8 GiB 8300 Linux filesystem Please help with removing the old and inexistent kernels from Grub.

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• Prepping the Raspberry Pi for Java Excellence (part 1)

  - by HecklerMark

  I've only recently been able to begin working seriously with my first Raspberry Pi, received months ago but hastily shelved in preparation for JavaOne. The Raspberry Pi and other diminutive computing platforms offer a glimpse of the potential of what is often referred to as the embedded space, the "Internet of Things" (IoT), or Machine to Machine (M2M) computing. I have a few different configurations I want to use for multiple Raspberry Pis, but for each of them, I'll need to perform the following common steps to prepare them for their various tasks: Load an OS onto an SD card Get the Pi connected to the network Load a JDK I've been very happy to see good friend and JFXtras teammate Gerrit Grunwald document how to do these things on his blog (link to article here - check it out!), but I ran into some issues configuring wi-fi that caused me some needless grief. Not knowing if any of the pitfalls were caused by my slightly-older version of the Pi and not being able to find anything specific online to help me get past it, I kept chipping away at it until I broke through. The purpose of this post is to (hopefully) help someone else recognize the same issues if/when they encounter them and work past them quickly. There is a great resource page here that covers several ways to get the OS on an SD card, but here is what I did (on a Mac): Plug SD card into reader on/in Mac Format it (FAT32) Unmount it (diskutil unmountDisk diskn, where n is the disk number representing the SD card) Transfer the disk image for Debian to the SD card (dd if=2012-08-08-wheezy-armel.img of=/dev/diskn bs=1m) Eject the card from the Mac (diskutil eject diskn) There are other ways, but this is fairly quick and painless, especially after you do it several times. Yes, I had to do that dance repeatedly (minus formatting) due to the wi-fi issues, as it kept killing the ability of the Pi to boot. You should be able to dramatically reduce the number of OS loads you do, though, if you do a few things with regard to your wi-fi. Firstly, I strongly recommend you purchase the Edimax EW-7811Un wi-fi adapter. This adapter/chipset has been proven with the Raspberry Pi, it's tiny, and it's cheap. Avoid unnecessary aggravation and buy this one! Secondly, visit this page for a script and instructions regarding how to configure your new wi-fi adapter with your Pi. Here is the rub, though: there is a missing step. At least for my combination of Pi version, OS version, and uncanny gift of timing and luck there was. :-) Here is the sequence of steps I used to make the magic happen: Plug your newly-minted SD card (with OS) into your Pi and connect a network cable (for internet connectivity) Boot your Pi. On the first boot, do the following things: Opt to have it use all space on the SD card (will require a reboot eventually) Disable overscan Set your timezone Enable the ssh server Update raspi-config Reboot your Pi. This will reconfigure the SD to use all space (see above). After you log in (UID: pi, password: raspberry), upgrade your OS. This was the missing step for me that put a merciful end to the repeated SD card re-imaging and made the wi-fi configuration trivial. To do so, just type sudo apt-get upgrade and give it several minutes to complete. Pour yourself a cup of coffee and congratulate yourself on the time you've just saved.  ;-) With the OS upgrade finished, now you can follow Mr. Engman's directions (to the letter, please see link above), download his script, and let it work its magic. One aside: I plugged the little power-sipping Edimax directly into the Pi and it worked perfectly. No powered hub needed, at least in my configuration. To recap, that OS upgrade (at least at this point, with this combination of OS/drivers/Pi version) is absolutely essential for a smooth experience. Miss that step, and you're in for hours of "fun". Save yourself! I'll pick up next time with more of the Java side of the RasPi configuration, but as they say, you have to cross the moat to get into the castle. Hopefully, this will help you do just that. Until next time! All the best, Mark 

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• Measuring ASP.NET and SharePoint output cache

  - by DigiMortal

  During ASP.NET output caching week in my local blog I wrote about how to measure ASP.NET output cache. As my posting was based on real work and real-life results then I thought that this posting is maybe interesting to you too. So here you can read what I did, how I did and what was the result. Introduction Caching is not effective without measuring it. As MVP Henn Sarv said in one of his sessions then you will get what you measure. And right he is. Lately I measured caching on local Microsoft community portal to make sure that our caching strategy is good enough in environment where this system lives. In this posting I will show you how to start measuring the cache of your web applications. Although the application measured is built on SharePoint Server publishing infrastructure, all those counters have same meaning as similar counters under pure ASP.NET applications. Measured counters I used Performance Monitor and the following performance counters (their names are similar on ASP.NET and SharePoint WCMS): Total number of objects added – how much objects were added to output cache. Total object discards – how much objects were deleted from output cache. Cache hit count – how many times requests were served by cache. Cache hit ratio – percent of requests served from cache. The first three counters are cumulative while last one is coefficient. You can use also other counters to measure the full effect of caching (memory, processor, disk I/O, network load etc before and after caching). Measuring process The measuring I describe here started from freshly restarted web server. I measured application during 12 hours that covered also time ranges when users are most active. The time range does not include late evening hours and night because there is nothing to measure during these hours. During measuring we performed no maintenance or administrative tasks on server. All tasks performed were related to usual daily content management and content monitoring. Also we had no advertisement campaigns or other promotions running at same time. The results You can see the results on following graphic.   Total number of objects added   Total object discards   Cache hit count   Cache hit ratio You can see that adds and discards are growing in same tempo. It is good because cache expires and not so popular items are not kept in memory. If there are more popular content then the these lines may have bigger distance between them. Cache hit count grows faster and this shows that more and more content is served from cache. In current case it shows that cache is filled optimally and we can do even better if we tune caches more. The site contains also pages that are discarded when some subsite changes (page was added/modified/deleted) and one modification may affect about four or five pages. This may also decrease cache hit count because during day the site gets about 5-10 new pages. Cache hit ratio is currently extremely good. The suggested minimum is about 85% but after some tuning and measuring I achieved 98.7% as a result. This is due to the fact that new pages are most often requested and after new pages are added the older ones are requested only sometimes. So they get discarded from cache and only some of these will return sometimes back to cache. Although this may also indicate the need for additional SEO work the result is very well in technical means. Conclusion Measuring ASP.NET output cache is not complex thing to do and you can start by measuring performance of cache as a start. Later you can move on and measure caching effect to other counters such as disk I/O, network, processors etc. What you have to achieve is optimal cache that is not full of items asked only couple of times per day (you can avoid this by not using too long cache durations). After some tuning you should be able to boost cache hit ratio up to at least 85%.

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• Introducing Oracle System Assistant

  - by B.Koch

  by Josh Rosen One of the challenges with today's servers is getting the server up and running and understanding what all of the steps are once you plug the server in for the first time. So many different pieces come into play: installing drivers, updating firmware, configuring RAID, and provisioning the operating system. All of these steps must be done before you can even start using the server. Finding the latest firmware and drivers, making sure you have the right versions, and knowing that all the different software and firmware components work together properly can be a real challenge. If not done correctly, such as if you separately downloading disk firmware or controller firmware that doesn't match the existing OS drivers, you could experience bugs, performance problems, and incompatibilities. Gone are the days of having to locate the tools and drivers media that shipped with the server only to find out that newer versions of software and firmware are available on the web. Oracle has solved these challenges in the new X3-2 family of servers by introducing Oracle System Assistant. Oracle System Assistant is an innovative tool that is built-in to every new x86 server. It provides step-by-step assistance with configuring the server, updating firmware and drivers, and provisioning the operating system. Once you have completed all of the steps in the Oracle System Assistant tool, the server is ready to use. Oracle System Assistant was designed to be easy and straightforward. Starting it is as simple as pressing F9 when the server is booting. You'll need a keyboard, monitor, and mouse or you can use the remote console feature of Oracle ILOM (Integrated Lights Out Manager) to access a virtual KVM to the server from any machine. From there Oracle System Assistant will walk you through each of the steps necessary to set up your server. After configuring the network settings for Oracle System Assistant, the next step is to check for any new software or firmware for the server. Oracle System Assistant connects back to Oracle using your My Oracle Support account and downloads any updates that were made available to you for this specific server. This is where you really start to see the innovation that went into Oracle System Assistant. Firmware for Oracle ILOM and BIOS, operating system drivers, and other system firmware (including for option cards and disk drivers) come as a single bundle, downloading as a single unit, that has been engineered and tested to work together by Oracle. Oracle System Assistant figures out the right combination for your server, so you don't have to. Now that the server has the latest firmware, Oracle System Assistant will next walk you through configuring the hardware. From Oracle System Assistant, you can configure many Oracle ILOM settings, including the network settings and initial user accounts. This ensures that ILOM is accessible and ready to use. Oracle System Assistant is where all parts of the server come together. In addition to communicating with Oracle ILOM and interacting with BIOS, Oracle System Assistant understands and can configure the storage subsystem. Before installing the operating system, Oracle System Assistant can detect the storage configuration and configure RAID for all disks in the system. At this point, the server is ready to be provisioned with the host operating system. You can use Oracle System Assistant to provision a supported OS, including Oracle Linux, Oracle VM, RHEL, SuSe Linux, and Windows. And by using Oracle System Assistant, you can be sure that the proper OS drivers are installed for each of the installed hardware components. With Oracle System Assistant, initial setup of the server has never been easier. If we can innovate around problems and find solutions to make our servers easier to manage, this reduces IT costs and makes managing servers simpler. I think with Oracle System Assistant we have done just that. Josh Rosen is a Principal Product Manager at Oracle and previously spent more than a decade as a developer and architect of system management software. Josh has worked on system management for many of Oracle's hardware products ranging from the earliest blade systems to the latest Oracle x86 servers.

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• How do I fix a corrupted harddrive after failed upgrade?

  - by Nil

  The problem originated when I was trying to fix this problem. Things went horribly, horribly wrong and I ended up with a new problem altogether. The last thing I did was run sudo apt-get install and that caused my system to freeze. I restarted my computer and it would not boot from the harddrive. I ran a copy of Ubuntu 12.10 from a flashdrive that I had and ran gparted to see if my partitions were all there. It returned this message: Invalid partition table on /dev/sda -- wrong signature 5208. The drive appeared as a 2TiB unallocated drive with an error. The drive had 4 partitions before (plus random unallocated space). There was a fat32 partition, an ext4 partition which contained ubuntu 13.04/13.10 (I don't even know which one at this point), an extended partition which contained a swap partition for my ubuntu partition (I was meaning to move that ubuntu partition into the extended partition, never got around to it), and another partition (I don't remember how I formatted it). I should also mention this is a 1TB harddrive. So in short, I have a corrupted partition table on my primary harddrive from which I boot from, how can I fix this? I tried mounting the drive with sudo mount /dev/sda1 /media/ubuntu then I changed my directory to said folder and tried to list files and this monstrosity happened: $ ls ls: cannot access ??w?j^?.: Input/output error ls: cannot access ??(? ?x?.|: Input/output error ls: cannot access 6W_@?)?._??: Input/output error ls: cannot access HB0v???.A}?: Input/output error ls: cannot access ???.?X: Input/output error ls: cannot access t)?.+?l: Input/output error ls: cannot access ?h@ ?.@ : Input/output error ls: cannot access >? @??.???: Input/output error ls: cannot access m???.??: Input/output error ls: cannot access @ if??a?: Input/output error ls: cannot access ?M!vN$?.??n: Input/output error ls: cannot access ?o? ??.Bm`: Input/output error ls: cannot access ?:I??? M. : Input/output error ls: cannot access W??.??: Input/output error ls: cannot access ?: Input/output error ls: cannot access ?W?s??: Input/output error ls: cannot access ?v?k?.???: Input/output error ls: cannot access 5?$<N??: Input/output error .x????.??i: Input/output error ls: cannot access je????.j?1: Input/output error XjD?.???: Input/output error ls: cannot access W??n???.?: Input/output error ls: cannot access ?^x.$"?: Input/output error ls: cannot access !??*!??j.??: Input/output error ls: cannot access '-??k?^?.???: Input/output error ls: cannot access b?w?w?b.\??: Input/output error ls: cannot access o????"z.??B: Input/output error ls: cannot access ??b?h.?3-: Input/output error ls: cannot access ??.$7: Input/output error ls: cannot access )??K.bk: Input/output error ls: cannot access s??z?.?(?: Input/output error ls: cannot access ?F@?0?.@?: Input/output error .?D: Input/output error .??: Input/output error ls: cannot access?????. @: Input/output error ls: cannot access ?/?? ?.??: No such file or directory ls: cannot access rk?p4q(?.?k: Input/output error This looks promising. This is the output of fdisk -l $ sudo fdisk -l /dev/sda Warning: ignoring extra data in partition table 5 Warning: ignoring extra data in partition table 5 Warning: ignoring extra data in partition table 5 Warning: invalid flag 0x5208 of partition table 5 will be corrected by w(rite) Disk /dev/sda: 2199.0 GB, 2199023132672 bytes 255 heads, 63 sectors/track, 267349 cylinders, total 4294967056 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: 0x44fdfe06 Device Boot Start End Blocks Id System /dev/sda1 113305600 894715903 390705152 c W95 FAT32 (LBA) /dev/sda2 894715904 1489307647 297295872 83 Linux /dev/sda3 1489309694 1497307135 3998721 5 Extended /dev/sda4 1497309184 1953523711 228107264 7 HPFS/NTFS/exFAT /dev/sda5 ? 3013257822 3688738171 337740175 aa Unknown

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• How to convert my backup.cmd into something I can run in Linux?

  - by blade19899

  Back in the day when i was using windows(and a noob at everything IT) i liked batch scripting so much that i wrote a lot of them and one i am pretty proud of that is my backup.cmd(see below). I am pretty basic with the linux bash sudo/apt-get/sl/ls/locate/updatedb/etc... I don't really know the full power of the terminal. If you see the code below can i get it to work under (Ubuntu)linux :) by rewriting some of the windows code with the linux equivalent (btw:this works under xp/vista/7 | dutch/english) @echo off title back it up :home cls echo ÉÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ» echo º º echo º typ A/B for the options º echo º º echo ÌÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ͹ echo º º echo º "A"=backup options º echo º º echo º "B"=HARDDISK Options º echo º º echo º º echo ÈÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍŒ set /p selection=Choose: Goto %selection% :A cls echo ÉÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ» echo º º echo º typ 1 to start that backup º echo º º echo ÌÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ͹ echo º º echo º "A"=backup options º echo º È1=Documents,Pictures,Music,Videos,Downloads º echo º º echo º "B"=HARDDISK Options º echo º º echo ÈÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍŒ set /p selection=Choose: Goto %selection% :B cls echo ÉÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ» echo º º echo º typ HD to start the disk check º echo º º echo ÌÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ͹ echo º º echo º "A"=backup options º echo º º echo º "B"=HARDDISK Options º echo º ÈHD=find and repair bad sectors º echo º º echo ÈÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍŒ set /p selection=Choose: Goto %selection% :1 cls if exist "%userprofile%\desktop" (set desk=desktop) else (set desk=Bureaublad) if exist "%userprofile%\documents" (set docs=documents) else (set docs=mijn documenten) if exist "%userprofile%\pictures" (set pics=pictures) else (echo cant find %userprofile%\pictures) if exist "%userprofile%\music" (set mus=music) else (echo cant find %userprofile%\music) if exist "%userprofile%\Videos" (set vids=videos) else (echo cant find %userprofile%\videos) if exist "%userprofile%\Downloads" (set down=downloads) else (echo cant find %userprofile%\Downloads) cls echo. examples (D:\) (D:\Backup) (D:\Backup\18-4-2011) echo. echo. if there is no "D:\backup" folder then the folder will be created echo. set drive= set /p drive=storage: echo start>>backup.log echo Name:%username%>>backup.log echo Date:%date%>>backup.log echo Time:%time%>>backup.log echo ========================================%docs%===========================================>>backup.log echo %docs% echo Source:"%userprofile%\%docs%" echo Destination:"%drive%\%username%\%docs%" echo %time%>>backup.log xcopy "%userprofile%\%docs%" "%drive%\%username%\%docs%" /E /I>>Backup.log echo 20%% cls echo ========================================"%pics%"=========================================>>backup.log echo "%pics%" echo Source:"%userprofile%\%pics%" echo Destination:"%drive%\%username%\%pics%" echo %time%>>backup.log xcopy "%userprofile%\%pics%" "%drive%\%username%\%pics%" /E /I>>Backup.log echo 40%% cls echo ========================================"%mus%"=========================================>>backup.log echo "%mus%" echo Source:"%userprofile%\%mus%" echo Destination:"%drive%\%username%\%mus%" echo %time%>>backup.log xcopy "%userprofile%\%mus%" "%drive%\%username%\%mus%" /E /I>>Backup.log echo 60%% cls echo ========================================"%vids%"========================================>>backup.log echo %vids% echo Source:"%userprofile%\%vids%" echo Destination:"%drive%\%username%\%vids%" echo %time%>>backup.log xcopy "%userprofile%\%vids%" "%drive%\%username%\%vids%" /E /I>>Backup.log echo 80%% cls echo ========================================"%down%"========================================>>backup.log echo "%down%" echo Source:"%userprofile%\%down%" echo Destination:"%drive%\%username%\%down%" echo %time%>>backup.log xcopy "%userprofile%\%down%" "%drive%\%username%\%down%" /E /I>>Backup.log echo end>>backup.log echo %username% %date% %time%>>backup.log echo 100%% cls echo backup Compleet copy "backup.log" "%drive%\%username%" del "backup.log" pushd "%drive%\%username%" echo close backup.log to continue with backup script "backup.log" echo press any key to retun to the main menu pause>nul goto :home :HD echo finds and repairs bad sectors echo typ in harddisk letter (C: D: E:) set HD= set /p HD=Hard Disk: chkdsk %HD% /F /R /X pause goto :home

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• UEFI Dual-Boot - Ubuntu 12.04.3 + Windows 8.1 (One GPT HDD)

  - by swafbrother

  UEFI Dual-Boot - Ubuntu 12.04.3 + Windows 8.1 (One GPT HDD) Hello, I'm having trouble setting up a dual-boot (Ubuntu 12.04 LTS and Windows 8.1) in my ASUS K55VM laptop's hard drive disk (500 GB). I was mostly following tutorials for doing this, but at some point something has gone wrong. Up to now, I have followed these steps: I formatted my HDD into GPT. I clean-installed Windows 8.1. I didn't prevent Windows from choosing the partitions to use and it created these partitions: A Recovery partition (sda1). An EFI System Partition (sda2). A Microsoft Reserved Partition (sda3). A Windows Data Partition or C drive (sda4). I reduced the Windows Data Partition via Windows' Disk Management. I made a bootable USB Stick with Ubuntu 12.04 LTS from ISO, using Universal USB Installer. I created these partitions for Ubuntu: A Boot partition, mounted at /boot (sda5). A Root partition, mounted at / (sda6). A Swap partition (sda7). In Device for boot loader installation I chose: /dev/sda. Then, when I rebooted, it went straight into Ubuntu. So I installed Boot-Repair, and clicked on Recommended Repair. It automatically did its job without asking for anything. I rebooted and Grub showed up, with a lot of options. At this point I had a decent dual-boot setup; Ubuntu and both Windows entries worked fine: Ubuntu. Windows Boot UEFI Loader. Windows UEFI bkpbootmgfw.efi. I executed this command: sudo grub-install --force /dev/sda5. Then I tried to make Windows 8.1's Boot Manager the main boot manager, so that I could choose which OS to boot into from a menu. I downloaded EasyBCD on Windows. It showed 2 Ubuntu entries and 1 Windows entry. I went into BCD Deployment tab and clicked on Write MBR. At this point, I went into BIOS and made Windows Boot Manager the first boot option. When I rebooted, I got a black screen with the message efidisk read error, and then (I guess) it switched to the next boot option, which is Ubuntu, resulting in Grub showing up. From Grub, Ubuntu entry is working and so are both Windows entries. If I choose Ubuntu, it normally boots into Ubuntu. But if I choose Windows, it goes into Windows' boot manager. In Windows' boot manager, a menu shows up: Ubuntu. Ubuntu. Windows 8.1. If I choose Windows, it boots into Windows without any problem. If I choose Ubuntu, it boots into Grub (back to step 14). Here's my BootInfo Summary: http://paste.ubuntu.com/6698171/ Windows Boot Manager is clearly not working as expected; I can't directly boot into it and I can't boot into it from BIOS either (efidisk read error again). If I want to boot into Windows I need to boot into Grub first, which is the opposite of what I wanted. I need help at this point. What is the best thing I can do? Is there a more reliable and/or simpler way of acomplishing a satisfying dual-boot for this situation? Can someone provide a way for going back to step 8, where I had a more efficient dual-boot setup? If only I could undo what I did with Easy BCD and skip Windows' Boot Menu... Can someone provide a way to fix this mess? Thanks in advance and sorry for the length of this, I wanted to be exhaustive.

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• Slow Ubuntu 10.04 after long time unused

  - by Winston Ewert

  I'm at spring break so I'm back at my parent's house. I've turned my computer on which has been off since January and its unusably slow. This was not the case when I last used the computer in January. It is running 10.04, Memory: 875.5 MB CPU: AMD Athlon 64 X2 Dual Core Processor 4400+ Available Disk Space: 330.8 GB I'm not seeing a large usage of either memory or Disk I/O. If I look at my list of processes there is only a very small amount of CPU usage. However, if I hover over the CPU usage graph that I've on the top bar, I sometimes get really high readings like 100%. It took a long time to boot, to open firefox, to open a link in firefox. As far as I can tell everything that the computer tries to do is just massively slow. Right now, I'm apt-get dist-upgrading to install any updates that I will have missed since last time this computer was on. Any ideas as to what is going on here? UPDATE: I thought to check dmesg and it has a lot of entries like this: [ 1870.142201] ata3.00: exception Emask 0x0 SAct 0x7 SErr 0x0 action 0x0 [ 1870.142206] ata3.00: irq_stat 0x40000008 [ 1870.142210] ata3.00: failed command: READ FPDMA QUEUED [ 1870.142217] ata3.00: cmd 60/08:10:c0:4a:65/00:00:03:00:00/40 tag 2 ncq 4096 in [ 1870.142218] res 41/40:00:c5:4a:65/00:00:03:00:00/40 Emask 0x409 (media error) <F> [ 1870.142221] ata3.00: status: { DRDY ERR } [ 1870.142223] ata3.00: error: { UNC } [ 1870.143981] ata3.00: SB600 AHCI: limiting to 255 sectors per cmd [ 1870.146758] ata3.00: SB600 AHCI: limiting to 255 sectors per cmd [ 1870.146761] ata3.00: configured for UDMA/133 [ 1870.146777] ata3: EH complete [ 1872.092269] ata3.00: exception Emask 0x0 SAct 0x7 SErr 0x0 action 0x0 [ 1872.092274] ata3.00: irq_stat 0x40000008 [ 1872.092278] ata3.00: failed command: READ FPDMA QUEUED [ 1872.092285] ata3.00: cmd 60/08:00:c0:4a:65/00:00:03:00:00/40 tag 0 ncq 4096 in [ 1872.092287] res 41/40:00:c5:4a:65/00:00:03:00:00/40 Emask 0x409 (media error) <F> [ 1872.092289] ata3.00: status: { DRDY ERR } [ 1872.092292] ata3.00: error: { UNC } [ 1872.094050] ata3.00: SB600 AHCI: limiting to 255 sectors per cmd [ 1872.096795] ata3.00: SB600 AHCI: limiting to 255 sectors per cmd [ 1872.096798] ata3.00: configured for UDMA/133 [ 1872.096814] ata3: EH complete [ 1874.042279] ata3.00: exception Emask 0x0 SAct 0x7 SErr 0x0 action 0x0 [ 1874.042285] ata3.00: irq_stat 0x40000008 [ 1874.042289] ata3.00: failed command: READ FPDMA QUEUED [ 1874.042296] ata3.00: cmd 60/08:10:c0:4a:65/00:00:03:00:00/40 tag 2 ncq 4096 in [ 1874.042297] res 41/40:00:c5:4a:65/00:00:03:00:00/40 Emask 0x409 (media error) <F> [ 1874.042300] ata3.00: status: { DRDY ERR } [ 1874.042302] ata3.00: error: { UNC } [ 1874.044048] ata3.00: SB600 AHCI: limiting to 255 sectors per cmd [ 1874.046837] ata3.00: SB600 AHCI: limiting to 255 sectors per cmd [ 1874.046840] ata3.00: configured for UDMA/133 [ 1874.046861] sd 2:0:0:0: [sda] Unhandled sense code [ 1874.046863] sd 2:0:0:0: [sda] Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE [ 1874.046867] sd 2:0:0:0: [sda] Sense Key : Medium Error [current] [descriptor] [ 1874.046872] Descriptor sense data with sense descriptors (in hex): [ 1874.046874] 72 03 11 04 00 00 00 0c 00 0a 80 00 00 00 00 00 [ 1874.046883] 03 65 4a c5 [ 1874.046886] sd 2:0:0:0: [sda] Add. Sense: Unrecovered read error - auto reallocate failed [ 1874.046892] sd 2:0:0:0: [sda] CDB: Read(10): 28 00 03 65 4a c0 00 00 08 00 [ 1874.046900] end_request: I/O error, dev sda, sector 56969925 [ 1874.046920] ata3: EH complete I'm not certain, but that looks like my problem may be a failing hard drive. But the drive is less then a year old, it really shouldn't be failing now...

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• VirtualBox 3.2 is released! A Red Letter Day?

  - by Fat Bloke

  Big news today! A new release of VirtualBox packed full of innovation and improvements. Over the next few weeks we'll take a closer look at some of these new features in a lot more depth, but today we'll whet your appetite with the headline descriptions. To start with, we should point out that this is the first Oracle-branded version which makes today a real Red-letter day ;-)  Oracle VM VirtualBox 3.2 Version 3.2 moves VirtualBox forward in 3 main areas ( handily, all beginning with "P" ) : performance, power and supported guest operating system platforms.  Let's take a look: Performance New Latest Intel hardware support - Harnessing the latest in chip-level support for virtualization, VirtualBox 3.2 supports new Intel Core i5 and i7 processor and Intel Xeon processor 5600 Series support for Unrestricted Guest Execution bringing faster boot times for everything from Windows to Solaris guests; New Large Page support - Reducing the size and overhead of key system resources, Large Page support delivers increased performance by enabling faster lookups and shorter table creation times. New In-hypervisor Networking - Significant optimization of the networking subsystem has reduced context switching between guests and host, increasing network throughput by up to 25%. New New Storage I/O subsystem - VirtualBox 3.2 offers a completely re-worked virtual disk subsystem which utilizes asynchronous I/O to achieve high-performance whilst maintaining high data integrity; New Remote Video Acceleration - The unique built-in VirtualBox Remote Display Protocol (VRDP), which is primarily used in virtual desktop infrastructure deployments, has been enhanced to deliver video acceleration. This delivers a rich user experience coupled with reduced computational expense, which is vital when servers are running hundreds of virtual machines; Power New Page Fusion - Traditional Page Sharing techniques have suffered from long and expensive cache construction as pages are scrutinized as candidates for de-duplication. Taking a smarter approach, VirtualBox Page Fusion uses intelligence in the guest virtual machine to determine much more rapidly and accurately those pages which can be eliminated thereby increasing the capacity or vm density of the system; New Memory Ballooning- Ballooning provides another method to increase vm density by allowing the memory of one guest to be recouped and made available to others; New Multiple Virtual Monitors - VirtualBox 3.2 now supports multi-headed virtual machines with up to 8 virtual monitors attached to a guest. Each virtual monitor can be a host window, or be mapped to the hosts physical monitors; New Hot-plug CPU's - Modern operating systems such Windows Server 2008 x64 Data Center Edition or the latest Linux server platforms allow CPUs to be dynamically inserted into a system to provide incremental computing power while the system is running. Version 3.2 introduces support for Hot-plug vCPUs, allowing VirtualBox virtual machines to be given more power, with zero-downtime of the guest; New Virtual SAS Controller - VirtualBox 3.2 now offers a virtual SAS controller, enabling it to run the most demanding of high-end guests; New Online Snapshot Merging - Snapshots are powerful but can eat up disk space and need to be pruned from time to time. Historically, machines have needed to be turned off to delete or merge snapshots but with VirtualBox 3.2 this operation can be done whilst the machines are running. This allows sophisticated system management with minimal interruption of operations; New OVF Enhancements - VirtualBox has supported the OVF standard for virtual machine portability for some time. Now with 3.2, VirtualBox specific configuration data is also stored in the standard allowing richer virtual machine definitions without compromising portability; New Guest Automation - The Guest Automation APIs allow host-based logic to drive operations in the guest; Platforms New USB Keyboard and Mouse - Support more guests that require USB input devices; New Oracle Enterprise Linux 5.5 - Support for the latest version of Oracle's flagship Linux platform; New Ubuntu 10.04 ("Lucid Lynx") - Support for both the desktop and server version of the popular Ubuntu Linux distribution; And as a man once said, "just one more thing" ... New Mac OS X (experimental) - On Apple hardware only, support for creating virtual machines run Mac OS X. All in all this is a pretty powerful release packed full of innovation and speedups. So what are you waiting for?  -FB 

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• Clever memory usage through the years

  - by Ben Emmett

  A friend and I were recently talking about the really clever tricks people have used to get the most out of memory. I thought I’d share my favorites, and would love to hear yours too! Interleaving on drum memory Back in the ye olde days before I’d been born (we’re talking the 50s / 60s here), working memory commonly took the form of rotating magnetic drums. These would spin at a constant speed, and a fixed head would read from memory when the correct part of the drum passed it by, a bit like a primitive platter disk. Because each revolution took a few milliseconds, programmers took to manually arranging information non-sequentially on the drum, timing when an instruction or memory address would need to be accessed, then spacing information accordingly around the edge of the drum, thus reducing the access delay. Similar techniques were still used on hard disks and floppy disks into the 90s, but have become irrelevant with modern disk technologies. The Hashlife algorithm Conway’s Game of Life has attracted numerous implementations over the years, but Bill Gosper’s Hashlife algorithm is particularly impressive. Taking advantage of the repetitive nature of many cellular automata, it uses a quadtree structure to store the hashes of pieces of the overall grid. Over time there are fewer and fewer new structures which need to be evaluated, so it starts to run faster with larger grids, drastically outperforming other algorithms both in terms of speed and the size of grid which can be simulated. The actual amount of memory used is huge, but it’s used in a clever way, so makes the list . Elite’s procedural generation Ok, so this isn’t exactly a memory optimization – more a storage optimization – but it gets an honorable mention anyway. When writing Elite, David Braben and Ian Bell wanted to build a rich world which gamers could explore, but their 22K memory was something of a limitation (for comparison that’s about the size of my avatar picture at the top of this page). They procedurally generated all the characteristics of the 2048 planets in their virtual universe, including the names, which were stitched together using a lookup table of parts of names. In fact the original plans were for 2^52 planets, but it was decided that that was probably too many. Oh, and they did that all in assembly language. Other games of the time used similar techniques too – The Sentinel’s landscape generation algorithm being another example. Modern Garbage Collectors Garbage collection in managed languages like Java and .NET ensures that most of the time, developers stop needing to care about how they use and clean up memory as the garbage collector handles it automatically. Achieving this without killing performance is a near-miraculous feet of software engineering. Much like when learning chemistry, you find that every time you think you understand how the garbage collector works, it turns out to be a mere simplification; that there are yet more complexities and heuristics to help it run efficiently. Of course introducing memory problems is still possible (and there are tools like our memory profiler to help if that happens to you) but they’re much, much rarer. A cautionary note In the examples above, there were good and well understood reasons for the optimizations, but cunningly optimized code has usually had to trade away readability and maintainability to achieve its gains. Trying to optimize memory usage without being pretty confident that there’s actually a problem is doing it wrong. So what have I missed? Tell me about the ingenious (or stupid) tricks you’ve seen people use. Ben

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• Booting the liveCD/USB in EFI mode fails on Samsung Tablet XE700T1A

  - by F.L.

  My tablet is Samsung Series 7 Slate (XE700T1A-A02FR (French Language)). It operates an Intel Sandy Bridge architecture. The main issue about this tablet is that it ships with an installed Windows 7 in (U)EFI mode (GPT partition table, etc.), so I'd like to get an EFI dual boot with Ubuntu. But it seems I can't boot on the liveCD in EFI mode. It starts loading (up to initrd), but I then get a blank (black) screen. I've tried the nomodeset kernel option (as well as removing quiet and splash) with no luck. [2012-09-27] I have used the Ubuntu 12.04.1 Desktop ISO (I have read somewhere that it is the only one that can boot in EFI mode). I'd say this has something to do with UEFI since the LiveCD boots in bios mode but not in efi mode. Besides, I am not sure my boot info will help, since I can't boot the LiveCD in EFI mode. As a result I can't install ubuntu in EFI mode. So it would be the boot info from the liveCD boot in bios mode. This happens on a ubuntu-12.04.1-desktop-amd64 iso used on a LiveUSB. Live USB was created by dd'ing the iso onto the full disk device (i.e. /dev/sdx no number) of the Flash drive. I have also tried copying the LiveCD files on a primary GPT partition, but with no luck, I just get the grub shell, no menu, no install option. [2012-09-28] I tried today a flash drive created with Ubuntu's Startup Disk Creator and the alternate 12.04.1 64 bit ISO. I get a grub menu in text mode (which meens it did start in efi mode) with install options / test options. But when I start any of these, I simply get a black screen (no cursor, neither mouse nor text-mode cursor). I tried removing the 'quiet' option and adding nomodeset and acpi=off, but it didn't do any good. So this is the same result as for the LiveCD. [2012-10-01] I have tried with a version of the secure remix version via usb-creator-gtk. The boot on the USB key has the same symptoms. Boot in EFI mode is impossible (I have menu but whatever entry I choose, I get the blank screen problem). The boot in BIOS mode works, I did the install. Then I used boot-repair to try installing grub-efi and get a system that would boot in efi mode. But I can't boot this system, because the EFI firmware doesn't seem to detect that sda contains a valid efi partition. Here is the resulting boot-info Boot info 1253554 [2012-10-01] Today, I have reinstalled the pre-shipped version of windows 7, and then installed ubuntu from a secure-remix iso dumped on USB flash drive vie usb-creator-gtk booted in BIOS mode. When install ended, I said "continue testing" then I used boot-repair to try get the bootloader installed. Now, when I boot the tablet, I get the grub menu, it can chainload windows 7 flawlessly. But when I try to start one of the ubuntu options I get the same old blank screen. Here is the new boot-info: Boot info 1253927 [2012-10-01] I tried installing the 3.3 kernel by chrooting a live usb boot (secure remix again) into the installed system. Same symptoms. I feel the key to this is that the device's efi firmware (which is EFI v2.0) would expose the graphics hardware in a way that prevents the kernel to initialize it, and thus prevents it from booting (the kernel stops all drive access just after the screen turns kind of very dark purple). Here is some info on the UEFI firmware as given by rEFInd: EFI revision: 2.00 Platform: x86_64 (64 bit) Firmware: American Megatrends 4.635 Screen Output: Graphics Output (UEFI), 800x600 [2012-10-08] This week end I tried loading the kernel with elilo. Eventhough I didn't have more luck on booting the kernel, elilo gives more info when loading the kernel. I think the next step is trying to load a kernel with EFI stub directly.

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• VirtualBox Clone Root HD / Ubuntu / Network issue

  - by john.graves(at)oracle.com

  When you clone a root Ubuntu disk in VirtualBox, one thing that gets messed up is the network card definition.  This is because Ubuntu (as it should) uses UDEV IDs for the network device.  When you boot your new disk, the network device ID has changed, so it creates a new eth1 device.  Unfortunately, this conflicts with the VirtualBox network setup.  What to do? Boot the box (no network) Edit the /etc/udev/rules.d/70-persistent-net.rules Delete the eth0 line and modify the eth1 line to be eth0 --------- Example OLD ----------- # This file was automatically generated by the /lib/udev/write_net_rules # program, run by the persistent-net-generator.rules rules file. # # You can modify it, as long as you keep each rule on a single # line, and change only the value of the NAME= key. # PCI device 0x8086:0x100e (e1000) <-------------------- Delete these two lines SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="08:00:27:d8:8d:15", ATTR{dev_id}=="0x0", ATTR{type}=="1", KERNEL=="eth*", NAME="eth0" # PCI device 0x8086:0x100e (e1000) ---Modify the next line and change eth1 to be eth0 SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="08:00:27:89:84:98", ATTR{dev_id}=="0x0", ATTR{type}=="1", KERNEL=="eth*", NAME="eth1" .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } ---------------------------------------- --------- Example NEW ----------- # This file was automatically generated by the /lib/udev/write_net_rules # program, run by the persistent-net-generator.rules rules file. # # You can modify it, as long as you keep each rule on a single # line, and change only the value of the NAME= key. # PCI device 0x8086:0x100e (e1000) SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="08:00:27:89:84:98", ATTR{dev_id}=="0x0", ATTR{type}=="1", KERNEL=="eth*", NAME="eth0" .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } ----------------------------------------

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• SQL Server IO handling mechanism can be severely affected by high CPU usage

  - by sqlworkshops

  Are you using SSD or SAN / NAS based storage solution and sporadically observe SQL Server experiencing high IO wait times or from time to time your DAS / HDD becomes very slow according to SQL Server statistics? Read on… I need your help to up vote my connect item – https://connect.microsoft.com/SQLServer/feedback/details/744650/sql-server-io-handling-mechanism-can-be-severely-affected-by-high-cpu-usage. Instead of taking few seconds, queries could take minutes/hours to complete when CPU is busy.In SQL Server when a query / request needs to read data that is not in data cache or when the request has to write to disk, like transaction log records, the request / task will queue up the IO operation and wait for it to complete (task in suspended state, this wait time is the resource wait time). When the IO operation is complete, the task will be queued to run on the CPU. If the CPU is busy executing other tasks, this task will wait (task in runnable state) until other tasks in the queue either complete or get suspended due to waits or exhaust their quantum of 4ms (this is the signal wait time, which along with resource wait time will increase the overall wait time). When the CPU becomes free, the task will finally be run on the CPU (task in running state).The signal wait time can be up to 4ms per runnable task, this is by design. So if a CPU has 5 runnable tasks in the queue, then this query after the resource becomes available might wait up to a maximum of 5 X 4ms = 20ms in the runnable state (normally less as other tasks might not use the full quantum).In case the CPU usage is high, let’s say many CPU intensive queries are running on the instance, there is a possibility that the IO operations that are completed at the Hardware and Operating System level are not yet processed by SQL Server, keeping the task in the resource wait state for longer than necessary. In case of an SSD, the IO operation might even complete in less than a millisecond, but it might take SQL Server 100s of milliseconds, for instance, to process the completed IO operation. For example, let’s say you have a user inserting 500 rows in individual transactions. When the transaction log is on an SSD or battery backed up controller that has write cache enabled, all of these inserts will complete in 100 to 200ms. With a CPU intensive parallel query executing across all CPU cores, the same inserts might take minutes to complete. WRITELOG wait time will be very high in this case (both under sys.dm_io_virtual_file_stats and sys.dm_os_wait_stats). In addition you will notice a large number of WAITELOG waits since log records are written by LOG WRITER and hence very high signal_wait_time_ms leading to more query delays. However, Performance Monitor Counter, PhysicalDisk, Avg. Disk sec/Write will report very low latency times.Such delayed IO handling also occurs to read operations with artificially very high PAGEIOLATCH_SH wait time (with number of PAGEIOLATCH_SH waits remaining the same). This problem will manifest more and more as customers start using SSD based storage for SQL Server, since they drive the CPU usage to the limits with faster IOs. We have a few workarounds for specific scenarios, but we think Microsoft should resolve this issue at the product level. We have a connect item open – https://connect.microsoft.com/SQLServer/feedback/details/744650/sql-server-io-handling-mechanism-can-be-severely-affected-by-high-cpu-usage - (with example scripts) to reproduce this behavior, please up vote the item so the issue will be addressed by the SQL Server product team soon.Thanks for your help and best regards,Ramesh MeyyappanHome: www.sqlworkshops.comLinkedIn: http://at.linkedin.com/in/rmeyyappan

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• Failed to install GRUB on a separate '/boot' partition on a fake RAID 0 (12.04LTS)

  - by gerben

  I'm having some problems getting GRUB configured for Ubuntu 12.04LTS on a fake RAID 0. I can either get the GRUB rescue prompt at startup, or just a GRUB prompt but I cannot boot to Ubuntu manually. How can I configure the GRUB to actually use the Ubuntu install? The steps taken: Installing Ubuntu on fake raid The Ubuntu installer cannot install Ubuntu on the drive. After defining the partitions to use it fails with "Error: ???", pressing OK terminates the installer. Therefore, I used GParted to configure the partitions: /dev/mapper/sil_agadaccfacbg : (the RAID configuration, created partition): /dev/mapper/sil_agadaccfacbg1:ext2, 200MiB, (with 'boot' flag) /dev/mapper/sil_agadaccfacbg3:ext2, 67.75GiB, (which will contain Ubuntu) /dev/mapper/sil_agadaccfacbg2:extended, 1.00GiB, (for swap) Contains: /dev/mapper/sil_agadaccfacbg5: unknown Because of the fake-RAID, I already mounted the destination partitions before running the Ubuntu installer: > mkdir /mnt/boot > sudo mount /dev/mapper/sil_agadaccfacbg1 /mnt/boot > mkdir /mnt/ubuntu > sudo mount /dev/mapper/sil_agadaccfacbg3 /mnt/ubuntu In the installer I chose the following partition usage: /dev/mapper/sil_agadaccfacbg1 ext2, mount at /boot (209MB) /dev/mapper/sil_agadaccfacbg3 ext2, mount at / (72751MB) /dev/mapper/sil_agadaccfacbg5 swap Device for boot loader installation: /dev/mapper/sil_agadaccfacbg, linux device-mapper (striped) (74.0GB) This will install Ubuntu, but will fail to install GRUB (it seems to use /dev/sda no matter which one I choose) Installing GRUB with dpkg-reconfigure I followed this guide, but adapted it for two partitions: sudo mount /dev/mapper/sil_agadaccfacbg3 /mnt/ubuntu sudo mount --bind /dev /mnt/ubuntu/dev sudo mount --bind /proc /mnt/ubuntu/proc sudo mount --bind /sys /mnt/ubuntu/sys sudo mount /dev/mapper/sil_agadaccfacbg1 /mnt/boot sudo mount --bind /boot /mnt/boot sudo chroot /mnt/ubuntu dpkg-reconfigure grub-pc However, it does not ask where to install GRUB (I should choose /dev/mapper/sil_agadaccfacbg somewhere..) After reboot I get the GRUB rescue prompt with message no such device Installing GRUB with grub-install After the same mount commands as above, I continued with: > sudo grub-install --root-directory=/mnt/boot /dev/mapper/sil_agadaccfacbg This gives the following message: /usr/sbin/grub-probe: error: cannot find a device for /mnt/boot/boot/grub (is /dev mounted?) It does succeed when mounting just the boot partition : sudo mount /dev/mapper/sil_agadaccfacbg1 /mnt sudo grub-install --root-directory=/mnt/ /dev/mapper/sil_agadaccfacbg This finishes with: Installation finished. No error reported. After reboot I get the GRUB console, with welcome text. Attempting to manually start Ubuntu: ls (hd0) (hd0,msdos3) : (Ubuntu install partition) (hd0,msdos1) : (Ubuntu boot partition) (hd1) (hd1,msdos1) : (Ubuntu live USB) ls (hd0,msdos3)/ contains: - vmlinuz - lib/ - tmp/ - initrd.img - mnt/ - var/ - proc/ - boot/ - root/ - etc/ - run/ - media/ - sbin/ - bin/ - selinux/ - dev/ - srv/ - home/ - sys/ ls (hd0,msdos1)/ contains: -grub/ -boot/ -initrd.img-3.8.0-29-generic -vmlinuz-3.8.0.29-generic -config-3.8 linux (hd0,msdos3)/vmlinuz This returns "error: out of disk" Installing GRUB on Ubuntu partition with grub-install > sudo mount /dev/mapper/sil_agadaccfacbg3 /mnt > sudo grub-install --root-directory=/mnt/ /dev/mapper/sil_agadaccfacbg This finishes with message: > Installation finished. No error reported. After reboot get the message "error: out of disk" and the GRUB rescue prompt. Configuring GRUB with grub-mkconfig Attempting to run grub-mkconfig with different destinations results in the same message: /usr/sbin/grub-probe: error: cannot find a device for / (is /dev mounted?). Remarks: Initially I didn't use a separate /boot partition, but the GRUB install then also failed. Because some mention that a small partition at the beginning of the drive is necessary on old machines, I retried with a /boot partition This is a single boot (no other OS's installed/used)

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• Caching factory design

  - by max

  I have a factory class XFactory that creates objects of class X. Instances of X are very large, so the main purpose of the factory is to cache them, as transparently to the client code as possible. Objects of class X are immutable, so the following code seems reasonable: # module xfactory.py import x class XFactory: _registry = {} def get_x(self, arg1, arg2, use_cache = True): if use_cache: hash_id = hash((arg1, arg2)) if hash_id in _registry: return _registry[hash_id] obj = x.X(arg1, arg2) _registry[hash_id] = obj return obj # module x.py class X: # ... Is it a good pattern? (I know it's not the actual Factory Pattern.) Is there anything I should change? Now, I find that sometimes I want to cache X objects to disk. I'll use pickle for that purpose, and store as values in the _registry the filenames of the pickled objects instead of references to the objects. Of course, _registry itself would have to be stored persistently (perhaps in a pickle file of its own, in a text file, in a database, or simply by giving pickle files the filenames that contain hash_id). Except now the validity of the cached object depends not only on the parameters passed to get_x(), but also on the version of the code that created these objects. Strictly speaking, even a memory-cached object could become invalid if someone modifies x.py or any of its dependencies, and reloads it while the program is running. So far I ignored this danger since it seems unlikely for my application. But I certainly cannot ignore it when my objects are cached to persistent storage. What can I do? I suppose I could make the hash_id more robust by calculating hash of a tuple that contains arguments arg1 and arg2, as well as the filename and last modified date for x.py and every module and data file that it (recursively) depends on. To help delete cache files that won't ever be useful again, I'd add to the _registry the unhashed representation of the modified dates for each record. But even this solution isn't 100% safe since theoretically someone might load a module dynamically, and I wouldn't know about it from statically analyzing the source code. If I go all out and assume every file in the project is a dependency, the mechanism will still break if some module grabs data from an external website, etc.). In addition, the frequency of changes in x.py and its dependencies is quite high, leading to heavy cache invalidation. Thus, I figured I might as well give up some safety, and only invalidate the cache only when there is an obvious mismatch. This means that class X would have a class-level cache validation identifier that should be changed whenever the developer believes a change happened that should invalidate the cache. (With multiple developers, a separate invalidation identifier is required for each.) This identifier is hashed along with arg1 and arg2 and becomes part of the hash keys stored in _registry. Since developers may forget to update the validation identifier or not realize that they invalidated existing cache, it would seem better to add another validation mechanism: class X can have a method that returns all the known "traits" of X. For instance, if X is a table, I might add the names of all the columns. The hash calculation will include the traits as well. I can write this code, but I am afraid that I'm missing something important; and I'm also wondering if perhaps there's a framework or package that can do all of this stuff already. Ideally, I'd like to combine in-memory and disk-based caching.

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• Starting over and new to Ubuntu

  - by 2funnyyone

  We have been having repeated problems with our interent service and using windows xp & sp3 (users and premissions) I see no need for them. I started with computers long before windows. Every since sp 3 come out in 2009 I have had nothing but problems. I have lost so many computers to virius and trojans, we just stack them up. We are with Qwest/ Century link which is using advertising servers which I think is causing the problem. All the computers are networked together which is not how I set them up. I beleive Century link is networking them through assignment of a domain for our home. This causes all the computers to crash twice. This is getting expensive. We tried buying new harddrives but reinfect with hours of connecting to internet. I also beleive the modem, router and all computers are infected. I put combofix on this one and that is the only reason we are still online with this laptop. I am afraid to install new equipment because my partner and I are on SSDI and this cost a lot. I go to school at UOP and had to run off a flash and reboot this laptop to recovery every other day or so, this pass month. New plan is: We are getting ready to install new equipment but afraid to reinfect again. Need help to install new equipment. The plan is to use current internet services from Qwest/ now Century Link. The list of New equipment in order: Century link wireless modem is ZyXEL PK5000Z with 4 direct connect Ethernet ports Next Dell Optiplex 210L ( used auction purchase ) 2 gb ram 80 g hard drive Ubuntu 11.10 operating system Next Wireless D-Link router WBR-1310 with 4 direct connect Ethernet ports OK-------- Purchased Dell OEM disk for Repair or Reinstalling Windows XP Professional Operating system (2 roommates as well) All infected computers are Dell desktops or laptops with XP Pro Also purchasing Ubuntu 12.04 for 3 computers. We like the way it runs but still learning it. Questions 1] How do we fdisk the infected computers without infecting new system. We have Dos disks, but none have floppy dish drive. We do have a new floppy disk drive and usb adapter we purchased from Amazon. 2] We are thinking Avast internet security because of the boot scan. We want all software loaded before reconnecting. We can manually load our internet provider information. We purchased StopZilla $100 for 5 computers, but not sure that is what we need. But need how to setup ports security and services we will need. Really lost at this part. So we are safe when we go back on the internet. 3] Want to connect reloaded fdisk systems to router as public connection and no sharing. Do not want to network all computers. 4] Want parental/ ownership control from Ubuntu system for internet connection (Children and friends). Do we restrict at the modem and/ or router? Any help would be a blessing. I do not want to go alone on this anymore.

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• Dynamically load and call delegates based on source data

  - by makerofthings7

  Assume I have a stream of records that need to have some computation. Records will have a combination of these functions run Sum, Aggregate, Sum over the last 90 seconds, or ignore. A data record looks like this: Date;Data;ID Question Assuming that ID is an int of some kind, and that int corresponds to a matrix of some delegates to run, how should I use C# to dynamically build that launch map? I'm sure this idea exists... it is used in Windows Forms which has many delegates/events, most of which will never actually be invoked in a real application. The sample below includes a few delegates I want to run (sum, count, and print) but I don't know how to make the quantity of delegates fire based on the source data. (say print the evens, and sum the odds in this sample) using System; using System.Threading; using System.Collections.Generic; internal static class TestThreadpool { delegate int TestDelegate(int parameter); private static void Main() { try { // this approach works is void is returned. //ThreadPool.QueueUserWorkItem(new WaitCallback(PrintOut), "Hello"); int c = 0; int w = 0; ThreadPool.GetMaxThreads(out w, out c); bool rrr =ThreadPool.SetMinThreads(w, c); Console.WriteLine(rrr); // perhaps the above needs time to set up6 Thread.Sleep(1000); DateTime ttt = DateTime.UtcNow; TestDelegate d = new TestDelegate(PrintOut); List<IAsyncResult> arDict = new List<IAsyncResult>(); int count = 1000000; for (int i = 0; i < count; i++) { IAsyncResult ar = d.BeginInvoke(i, new AsyncCallback(Callback), d); arDict.Add(ar); } for (int i = 0; i < count; i++) { int result = d.EndInvoke(arDict[i]); } // Give the callback time to execute - otherwise the app // may terminate before it is called //Thread.Sleep(1000); var res = DateTime.UtcNow - ttt; Console.WriteLine("Main program done----- Total time --> " + res.TotalMilliseconds); } catch (Exception e) { Console.WriteLine(e); } Console.ReadKey(true); } static int PrintOut(int parameter) { // Console.WriteLine(Thread.CurrentThread.ManagedThreadId + " Delegate PRINTOUT waited and printed this:"+parameter); var tmp = parameter * parameter; return tmp; } static int Sum(int parameter) { Thread.Sleep(5000); // Pretend to do some math... maybe save a summary to disk on a separate thread return parameter; } static int Count(int parameter) { Thread.Sleep(5000); // Pretend to do some math... maybe save a summary to disk on a separate thread return parameter; } static void Callback(IAsyncResult ar) { TestDelegate d = (TestDelegate)ar.AsyncState; //Console.WriteLine("Callback is delayed and returned") ;//d.EndInvoke(ar)); } }

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• Video works with 'Try me' but not after install. What is the difference? U12.04LTS,

  - by HarveyP

  My hard drive got corrupted so I did a reinstall. Tested Youtube in FF during 'try me' and it worked - jerky, but it worked. Instal without all the updates (576 outstanding now) in order to get ff installed as per the demo - to no avail. In 'try me' mode ff NEVER crashed! After install ff crashed whilst I was typing in 'youtube' in the address field. When I finally got to youtube - no video. What is the difference between ff in try me and ff after install? Off to try some selected updates now to see if I can see it for myself. In previous installation I had several profiles and aliased ff with -safe-mode switch to simplify startup of most stable ff. Also found that ff startup in graphic mode worked better (but still without video) with all of the extensions disabled and all of the plugins set to "ask" and always denied ... I have SiS graphic card in SiS Motherboard for XP and ancient Hyundai ImageQuest QV770 monitor. I have Ubuntu 12.04.01 LTS 1 day after install with only the immediate upgrades requested to language pack (English UK). Using FR Alternative keyboard. Connected with domestic wifi network from Orange (FT) I really want to use Skype, but won't bother installing it (again) without video as I can do my sms on FB - whilst ff is not crashed ... Update ... Is something overflowing? I have just had to reboot in order to get ff to restart in any way shape or form - restart on crash form generates new crash form, etc. It was however a good half hour before it crashed so some improvement over conditions before disk corruption. I have now installed all of the critical updates (332 recommended updates still outstanding) which included some relating to ff. Still no video. Still crashing - especially when on Grepolis website. Since the re-install I have had a lovely 1024x768 screen, but after last ff crash and reboot I got a message about 'low graphics mode' and 'setting things myself'. I was not sufficiently tuned in at the time to take proper note - I have no doubt I shall see it again and shall report accordingly. I still have only laptop options for my screen and do not know how to rectify this. Spent a few days with ubuntu on a different, newer machine which has now suffered a graphics breakdown. Returned to this old one again, but with new flat screen Monitor. Found SIS drivers for my graphics BUT it is intended for Red Hat 7.2. I chose this over the version for 7.0 because I thought what the hell, I might not be able to do anything with either of them but this is the later one ... The file will not open with software manager - found a similar problem on Overclock but it has not helped me to install this driver. File name is sis_drv.o-410 and it is currently idling away in my Downloads folder ... I have tried the solution offered on another sis problem, but this shows that my xserver-xorg-video-sis driver is up to date. I am now at a loss as to how to proceed if I can't install the latest sis driver from sis ... Does nobody know how FF changes from "try-me" to "installed"? Any time I MUST have video I reboot from the disk again, but this is tedious! Also one of the things I mock most about MS is the constant rebooting ... UPDATE 10/6/2014 I have installed chromium-browser - worse, crashes even more often than ff.I have installed epiphany - better; Video works but not the associated soundtrack.FireFox is version 14.01 in 'try me' and version 29.0 from my install. Would it be useful to try to downgrade FireFox in order to get video?

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• Why is x=x++ undefined?

  - by ugoren

  It's undefined because the it modifies x twice between sequence points. The standard says it's undefined, therefore it's undefined. That much I know. But why? My understanding is that forbidding this allows compilers to optimize better. This could have made sense when C was invented, but now seems like a weak argument. If we were to reinvent C today, would we do it this way, or can it be done better? Or maybe there's a deeper problem, that makes it hard to define consistent rules for such expressions, so it's best to forbid them? So suppose we were to reinvent C today. I'd like to suggest simple rules for expressions such as x=x++, which seem to me to work better than the existing rules. I'd like to get your opinion on the suggested rules compared to the existing ones, or other suggestions. Suggested Rules: Between sequence points, order of evaluation is unspecified. Side effects take place immediately. There's no undefined behavior involved. Expressions evaluate to this value or that, but surely won't format your hard disk (strangely, I've never seen an implementation where x=x++ formats the hard disk). Example Expressions x=x++ - Well defined, doesn't change x. First, x is incremented (immediately when x++ is evaluated), then it's old value is stored in x. x++ + ++x - Increments x twice, evaluates to 2*x+2. Though either side may be evaluated first, the result is either x + (x+2) (left side first) or (x+1) + (x+1) (right side first). x = x + (x=3) - Unspecified, x set to either x+3 or 6. If the right side is evaluated first, it's x+3. It's also possible that x=3 is evaluated first, so it's 3+3. In either case, the x=3 assignment happens immediately when x=3 is evaluated, so the value stored is overwritten by the other assignment. x+=(x=3) - Well defined, sets x to 6. You could argue that this is just shorthand for the expression above. But I'd say that += must be executed after x=3, and not in two parts (read x, evaluate x=3, add and store new value). What's the Advantage? Some comments raised this good point. It's not that I'm after the pleasure of using x=x++ in my code. It's a strange and misleading expression. What I want is to be able to understand complicated expressions. Normally, a complicated expression is no more than the sum of its parts. If you understand the parts and the operators combining them, you can understand the whole. C's current behavior seems to deviate from this principle. One assignment plus another assignment suddenly doesn't make two assignments. Today, when I look at x=x++, I can't say what it does. With my suggested rules, I can, by simply examining its components and their relations.

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• Eclipse Hell . . . Failed to read the project description file (.project)

  - by Kobojunkie

  I think Eclipse is trying to make me miserable. A couple of hours ago, my project was working and compiling well. Suddenly that all changed. Eclipse somehow wipes out all changes I have made to my files(activity, manifest etc.) I make sure to save often but when I go to run the project, I get the error that I have a build error. I checked and there was none, so I go to close Eclipse, so I can reopen and see if the errors will go away. Instead what happens is Eclipse wipes clean all my files and I end up with a project on disk with lots of blank code files. I try to run anyway, and I get the error message below. Failed to read the project description file (.project) for 'com.example.android.nfc.simulator.FakeTagsActivity.FakeTagsActivity'. The file has been changed on disk, and it now contains invalid information. The project will not function properly until the description file is restored to a valid state. Anyone have an idea what in the world this is about and how I can rectify this?

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