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  • Improving TCP performance over a gigabit network lots of connections and high traffic for storage and streaming services

    - by Linux Guy
    I have two servers, Both servers hardware Specification are Processor : Dual Processor RAM : over 128 G.B Hard disk : SSD Hard disk Outging Traffic bandwidth : 3 Gbps network cards speed : 10 Gbps Server A : for Encoding videos Server B : for storage videos andstream videos over web interface like youtube The inbound bandwidth between two servers is 10Gbps , the outbound bandwidth internet bandwidth is 500Mpbs Both servers using public ip addresses in public and private network Both servers transfer and connection on nginx port , and the server B used for streaming media , like youtube stream videos Both servers in same network , when i do ping from Server A to Server B i got high time latency above 1.0ms , the time range time=52.7 ms to time=215.7 ms - This is the output of iftop utility 353Mb 707Mb 1.04Gb 1.38Gb 1.73Gb mqqqqqqqqqqqqqqqqqqqqqqqqqqqvqqqqqqqqqqqqqqqqqqqqqqqqqqqvqqqqqqqqqqqqqqqqqqqqqqqqqqqvqqqqqqqqqqqqqqqqqqqqqqqqqqqvqqqqqqqqqqqqqqqqqqqqqqqqqqq server.example.com => ip.address 6.36Mb 4.31Mb 1.66Mb <= 158Kb 94.8Kb 35.1Kb server.example.com => ip.address 1.23Mb 4.28Mb 1.12Mb <= 17.1Kb 83.5Kb 21.9Kb server.example.com => ip.address 395Kb 3.89Mb 1.07Mb <= 6.09Kb 109Kb 28.6Kb server.example.com => ip.address 4.55Mb 3.83Mb 1.04Mb <= 55.6Kb 45.4Kb 13.0Kb server.example.com => ip.address 649Kb 3.38Mb 1.47Mb <= 9.00Kb 38.7Kb 16.7Kb server.example.com => ip.address 5.00Mb 3.32Mb 1.80Mb <= 65.7Kb 55.1Kb 29.4Kb server.example.com => ip.address 387Kb 3.13Mb 1.06Mb <= 18.4Kb 39.9Kb 15.0Kb server.example.com => ip.address 3.27Mb 3.11Mb 1.01Mb <= 81.2Kb 64.5Kb 20.9Kb server.example.com => ip.address 1.75Mb 3.08Mb 2.72Mb <= 16.6Kb 35.6Kb 32.5Kb server.example.com => ip.address 1.75Mb 2.90Mb 2.79Mb <= 22.4Kb 32.6Kb 35.6Kb server.example.com => ip.address 3.03Mb 2.78Mb 1.82Mb <= 26.6Kb 27.4Kb 20.2Kb server.example.com => ip.address 2.26Mb 2.66Mb 1.36Mb <= 51.7Kb 49.1Kb 24.4Kb server.example.com => ip.address 586Kb 2.50Mb 1.03Mb <= 4.17Kb 26.1Kb 10.7Kb server.example.com => ip.address 2.42Mb 2.49Mb 2.44Mb <= 31.6Kb 29.7Kb 29.9Kb server.example.com => ip.address 2.41Mb 2.46Mb 2.41Mb <= 26.4Kb 24.5Kb 23.8Kb server.example.com => ip.address 2.37Mb 2.39Mb 2.40Mb <= 28.9Kb 27.0Kb 28.5Kb server.example.com => ip.address 525Kb 2.20Mb 1.05Mb <= 7.03Kb 26.0Kb 12.8Kb qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqq TX: cum: 102GB peak: 1.65Gb rates: 1.46Gb 1.44Gb 1.48Gb RX: 1.31GB 24.3Mb 19.5Mb 18.9Mb 20.0Mb TOTAL: 103GB 1.67Gb 1.48Gb 1.46Gb 1.50Gb I check the transfer speed using iperf utility From Server A to Server B # iperf -c 0.0.0.2 -p 8777 ------------------------------------------------------------ Client connecting to 0.0.0.2, TCP port 8777 TCP window size: 85.3 KByte (default) ------------------------------------------------------------ [ 3] local 0.0.0.1 port 38895 connected with 0.0.0.2 port 8777 [ ID] Interval Transfer Bandwidth [ 3] 0.0-10.8 sec 528 KBytes 399 Kbits/sec My Current Connections in Server B # netstat -an|grep ":8777"|awk '/tcp/ {print $6}'|sort -nr| uniq -c 2072 TIME_WAIT 28 SYN_RECV 1 LISTEN 189 LAST_ACK 139 FIN_WAIT2 373 FIN_WAIT1 3381 ESTABLISHED 34 CLOSING Server A Network Card Information Settings for eth0: Supported ports: [ TP ] Supported link modes: 100baseT/Full 1000baseT/Full 10000baseT/Full Supported pause frame use: No Supports auto-negotiation: Yes Advertised link modes: 10000baseT/Full Advertised pause frame use: No Advertised auto-negotiation: Yes Speed: 10000Mb/s Duplex: Full Port: Twisted Pair PHYAD: 0 Transceiver: external Auto-negotiation: on MDI-X: Unknown Supports Wake-on: d Wake-on: d Current message level: 0x00000007 (7) drv probe link Link detected: yes Server B Network Card Information Settings for eth2: Supported ports: [ FIBRE ] Supported link modes: 10000baseT/Full Supported pause frame use: No Supports auto-negotiation: No Advertised link modes: 10000baseT/Full Advertised pause frame use: No Advertised auto-negotiation: No Speed: 10000Mb/s Duplex: Full Port: Direct Attach Copper PHYAD: 0 Transceiver: external Auto-negotiation: off Supports Wake-on: d Wake-on: d Current message level: 0x00000007 (7) drv probe link Link detected: yes ifconfig server A eth0 Link encap:Ethernet HWaddr 00:25:90:ED:9E:AA inet addr:0.0.0.1 Bcast:0.0.0.255 Mask:255.255.255.0 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:1202795665 errors:0 dropped:64334 overruns:0 frame:0 TX packets:2313161968 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:893413096188 (832.0 GiB) TX bytes:3360949570454 (3.0 TiB) lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:65536 Metric:1 RX packets:2207544 errors:0 dropped:0 overruns:0 frame:0 TX packets:2207544 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:247769175 (236.2 MiB) TX bytes:247769175 (236.2 MiB) ifconfig Server B eth2 Link encap:Ethernet HWaddr 00:25:90:82:C4:FE inet addr:0.0.0.2 Bcast:0.0.0.2 Mask:255.255.255.0 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:39973046980 errors:0 dropped:1828387600 overruns:0 frame:0 TX packets:69618752480 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:3013976063688 (2.7 TiB) TX bytes:102250230803933 (92.9 TiB) lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:65536 Metric:1 RX packets:1049495 errors:0 dropped:0 overruns:0 frame:0 TX packets:1049495 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:129012422 (123.0 MiB) TX bytes:129012422 (123.0 MiB) Netstat -i on Server B # netstat -i Kernel Interface table Iface MTU Met RX-OK RX-ERR RX-DRP RX-OVR TX-OK TX-ERR TX-DRP TX-OVR Flg eth2 9000 0 42098629968 0 2131223717 0 73698797854 0 0 0 BMRU lo 65536 0 1077908 0 0 0 1077908 0 0 0 LRU I Turn up send/receive buffers on the network card to 2048 and problem still persist I increase the MTU for server A and problem still persist and i increase the MTU for server B for better connectivity and transfer speed but it couldn't transfer at all The problem is : as you can see from iperf utility, the transfer speed from server A to server B slow when i restart network service in server B the transfer in server A at full speed, after 2 minutes , it's getting slow How could i troubleshoot slow speed issue and fix it in server B ? Notice : if there any other commands i should execute in servers for more information, so it might help resolve the problem , let me know in comments

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  • Connecting Linux to WatchGuard Firebox SSL (OpenVPN client)

    Recently, I got a new project assignment that requires to connect permanently to the customer's network through VPN. They are using a so-called SSL VPN. As I am using OpenVPN since more than 5 years within my company's network I was quite curious about their solution and how it would actually be different from OpenVPN. Well, short version: It is a disguised version of OpenVPN. Unfortunately, the company only offers a client for Windows and Mac OS which shouldn't bother any Linux user after all. OpenVPN is part of every recent distribution and can be activated in a couple of minutes - both client as well as server (if necessary). WatchGuard Firebox SSL - About dialog Borrowing some files from a Windows client installation Initially, I didn't know about the product, so therefore I went through the installation on Windows 8. No obstacles (and no restart despite installation of TAP device drivers!) here and the secured VPN channel was up and running in less than 2 minutes or so. Much appreciated from both parties - customer and me. Of course, this whole client package and my long year approved and stable installation ignited my interest to have a closer look at the WatchGuard client. Compared to the original OpenVPN client (okay, I have to admit this is years ago) this commercial product is smarter in terms of file locations during installation. You'll be able to access the configuration and key files below your roaming application data folder. To get there, simply enter '%AppData%\WatchGuard\Mobile VPN' in your Windows/File Explorer and confirm with Enter/Return. This will display the following files: Application folder below user profile with configuration and certificate files From there we are going to borrow four files, namely: ca.crt client.crt client.ovpn client.pem and transfer them to the Linux system. You might also be able to isolate those four files from a Mac OS client. Frankly, I'm just too lazy to run the WatchGuard client installation on a Mac mini only to find the folder location, and I'm going to describe why a little bit further down this article. I know that you can do that! Feedback in the comment section is appreciated. Configuration of OpenVPN (console) Depending on your distribution the following steps might be a little different but in general you should be able to get the important information from it. I'm going to describe the steps in Ubuntu 13.04 (Raring Ringtail). As usual, there are two possibilities to achieve your goal: console and UI. Let's what it is necessary to be done. First of all, you should ensure that you have OpenVPN installed on your system. Open your favourite terminal application and run the following statement: $ sudo apt-get install openvpn network-manager-openvpn network-manager-openvpn-gnome Just to be on the safe side. The four above mentioned files from your Windows machine could be copied anywhere but either you place them below your own user directory or you put them (as root) below the default directory: /etc/openvpn At this stage you would be able to do a test run already. Just in case, run the following command and check the output (it's the similar information you would get from the 'View Logs...' context menu entry in Windows: $ sudo openvpn --config client.ovpn Pay attention to the correct path to your configuration and certificate files. OpenVPN will ask you to enter your Auth Username and Auth Password in order to establish the VPN connection, same as the Windows client. Remote server and user authentication to establish the VPN Please complete the test run and see whether all went well. You can disconnect pressing Ctrl+C. Simplifying your life - authentication file In my case, I actually set up the OpenVPN client on my gateway/router. This establishes a VPN channel between my network and my client's network and allows me to switch machines easily without having the necessity to install the WatchGuard client on each and every machine. That's also very handy for my various virtualised Windows machines. Anyway, as the client configuration, key and certificate files are located on a headless system somewhere under the roof, it is mandatory to have an automatic connection to the remote site. For that you should first change the file extension '.ovpn' to '.conf' which is the default extension on Linux systems for OpenVPN, and then open the client configuration file in order to extend an existing line. $ sudo mv client.ovpn client.conf $ sudo nano client.conf You should have a similar content to this one here: dev tunclientproto tcp-clientca ca.crtcert client.crtkey client.pemtls-remote "/O=WatchGuard_Technologies/OU=Fireware/CN=Fireware_SSLVPN_Server"remote-cert-eku "TLS Web Server Authentication"remote 1.2.3.4 443persist-keypersist-tunverb 3mute 20keepalive 10 60cipher AES-256-CBCauth SHA1float 1reneg-sec 3660nobindmute-replay-warningsauth-user-pass auth.txt Note: I changed the IP address of the remote directive above (which should be obvious, right?). Anyway, the required change is marked in red and we have to create a new authentication file 'auth.txt'. You can give the directive 'auth-user-pass' any file name you'd like to. Due to my existing OpenVPN infrastructure my setup differs completely from the above written content but for sake of simplicity I just keep it 'as-is'. Okay, let's create this file 'auth.txt' $ sudo nano auth.txt and just put two lines of information in it - username on the first, and password on the second line, like so: myvpnusernameverysecretpassword Store the file, change permissions, and call openvpn with your configuration file again: $ sudo chmod 0600 auth.txt $ sudo openvpn --config client.conf This should now work without being prompted to enter username and password. In case that you placed your files below the system-wide location /etc/openvpn you can operate your VPNs also via service command like so: $ sudo service openvpn start client $ sudo service openvpn stop client Using Network Manager For newer Linux users or the ones with 'console-phobia' I'm going to describe now how to use Network Manager to setup the OpenVPN client. For this move your mouse to the systray area and click on Network Connections => VPN Connections => Configure VPNs... which opens your Network Connections dialog. Alternatively, use the HUD and enter 'Network Connections'. Network connections overview in Ubuntu Click on 'Add' button. On the next dialog select 'Import a saved VPN configuration...' from the dropdown list and click on 'Create...' Choose connection type to import VPN configuration Now you navigate to your folder where you put the client files from the Windows system and you open the 'client.ovpn' file. Next, on the tab 'VPN' proceed with the following steps (directives from the configuration file are referred): General Check the IP address of Gateway ('remote' - we used 1.2.3.4 in this setup) Authentication Change Type to 'Password with Certificates (TLS)' ('auth-pass-user') Enter User name to access your client keys (Auth Name: myvpnusername) Enter Password (Auth Password: verysecretpassword) and choose your password handling Browse for your User Certificate ('cert' - should be pre-selected with client.crt) Browse for your CA Certificate ('ca' - should be filled as ca.crt) Specify your Private Key ('key' - here: client.pem) Then click on the 'Advanced...' button and check the following values: Use custom gateway port: 443 (second value of 'remote' directive) Check the selected value of Cipher ('cipher') Check HMAC Authentication ('auth') Enter the Subject Match: /O=WatchGuard_Technologies/OU=Fireware/CN=Fireware_SSLVPN_Server ('tls-remote') Finally, you have to confirm and close all dialogs. You should be able to establish your OpenVPN-WatchGuard connection via Network Manager. For that, click on the 'VPN Connections => client' entry on your Network Manager in the systray. It is advised that you keep an eye on the syslog to see whether there are any problematic issues that would require some additional attention. Advanced topic: routing As stated above, I'm running the 'WatchGuard client for Linux' on my head-less server, and since then I'm actually establishing a secure communication channel between two networks. In order to enable your network clients to get access to machines on the remote side there are two possibilities to enable that: Proper routing on both sides of the connection which enables both-direction access, or Network masquerading on the 'client side' of the connection Following, I'm going to describe the second option a little bit more in detail. The Linux system that I'm using is already configured as a gateway to the internet. I won't explain the necessary steps to do that, and will only focus on the additional tweaks I had to do. You can find tons of very good instructions and tutorials on 'How to setup a Linux gateway/router' - just use Google. OK, back to the actual modifications. First, we need to have some information about the network topology and IP address range used on the 'other' side. We can get this very easily from /var/log/syslog after we established the OpenVPN channel, like so: $ sudo tail -n20 /var/log/syslog Or if your system is quite busy with logging, like so: $ sudo less /var/log/syslog | grep ovpn The output should contain PUSH received message similar to the following one: Jul 23 23:13:28 ios1 ovpn-client[789]: PUSH: Received control message: 'PUSH_REPLY,topology subnet,route 192.168.1.0 255.255.255.0,dhcp-option DOMAIN ,route-gateway 192.168.6.1,topology subnet,ping 10,ping-restart 60,ifconfig 192.168.6.2 255.255.255.0' The interesting part for us is the route command which I highlighted already in the sample PUSH_REPLY. Depending on your remote server there might be multiple networks defined (172.16.x.x and/or 10.x.x.x). Important: The IP address range on both sides of the connection has to be different, otherwise you will have to shuffle IPs or increase your the netmask. {loadposition content_adsense} After the VPN connection is established, we have to extend the rules for iptables in order to route and masquerade IP packets properly. I created a shell script to take care of those steps: #!/bin/sh -eIPTABLES=/sbin/iptablesDEV_LAN=eth0DEV_VPNS=tun+VPN=192.168.1.0/24 $IPTABLES -A FORWARD -i $DEV_LAN -o $DEV_VPNS -d $VPN -j ACCEPT$IPTABLES -A FORWARD -i $DEV_VPNS -o $DEV_LAN -s $VPN -j ACCEPT$IPTABLES -t nat -A POSTROUTING -o $DEV_VPNS -d $VPN -j MASQUERADE I'm using the wildcard interface 'tun+' because I have multiple client configurations for OpenVPN on my server. In your case, it might be sufficient to specify device 'tun0' only. Simplifying your life - automatic connect on boot Now, that the client connection works flawless, configuration of routing and iptables is okay, we might consider to add another 'laziness' factor into our setup. Due to kernel updates or other circumstances it might be necessary to reboot your system. Wouldn't it be nice that the VPN connections are established during the boot procedure? Yes, of course it would be. To achieve this, we have to configure OpenVPN to automatically start our VPNs via init script. Let's have a look at the responsible 'default' file and adjust the settings accordingly. $ sudo nano /etc/default/openvpn Which should have a similar content to this: # This is the configuration file for /etc/init.d/openvpn## Start only these VPNs automatically via init script.# Allowed values are "all", "none" or space separated list of# names of the VPNs. If empty, "all" is assumed.# The VPN name refers to the VPN configutation file name.# i.e. "home" would be /etc/openvpn/home.conf#AUTOSTART="all"#AUTOSTART="none"#AUTOSTART="home office"## ... more information which remains unmodified ... With the OpenVPN client configuration as described above you would either set AUTOSTART to "all" or to "client" to enable automatic start of your VPN(s) during boot. You should also take care that your iptables commands are executed after the link has been established, too. You can easily test this configuration without reboot, like so: $ sudo service openvpn restart Enjoy stable VPN connections between your Linux system(s) and a WatchGuard Firebox SSL remote server. Cheers, JoKi

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  • The Linux Foundation Store: Linux gets silly

    <b>Cyber Cynic:</b> "...the Linux Foundation, the non-profit organization dedicated to growing Linux, has launched a new Linux merchandise store featuring a line of exclusive and original T-shirts, hats, mugs and other items that reflect "geek culture.""

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  • Embedded linux Development learning

    - by user1797375
    I come from a windows background and i am proficient with the .net platform. For work, i need to bring up a custom embedded system platform. We have bought the pandaboard ES as the test platform. The application is to stream images over the wifi. If you think about it, we are building something similar to a netgear router - the only difference being when you log into the device it serves images. Because my background is in windows i am not quite sure how to start off with embedded linux development. in reading through various sites i have come to the conclusion that going to linux as development host is the best option. Can some one point to me in the right direction regarding the set up. I have a windows machine that will be used for development purposes. I can either do a virtual box or setup a partition for linux. But the finer details are what throwing me off..what i need to know is 1) once i install linux what other software do I need - Code blocks, 2) what about toolchain 3) How to debug - through serial port ? 4) Is there a way to send the image built directly to the CF card? Thanks

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  • western digital caviar black. EXT4-fs error [migrated]

    - by azat
    Recently I update my HDD on desktop machine, and bought WD Caviar Black. But after I format & copy information to it (using dd), and fix partitions size: I have next errors in kern.log: Aug 27 16:04:35 home-spb kernel: [148265.326264] EXT4-fs error (device sdc2): ext4_mb_generate_buddy:739: group 9054, 32254 clusters in bitmap, 32258 in gd Aug 27 16:07:11 home-spb kernel: [148421.493483] EXT4-fs error (device sdc2): ext4_mb_generate_buddy:739: group 9045, 32254 clusters in bitmap, 32258 in gd Aug 27 16:09:17 home-spb kernel: [148546.481693] EXT4-fs error (device sdc2): ext4_mb_generate_buddy:739: group 10299, 32254 clusters in bitmap, 32258 in gd Aug 27 16:09:17 home-spb kernel: [148546.487147] JBD2: Spotted dirty metadata buffer (dev = sdc2, blocknr = 0). There's a risk of filesystem corruption in case of system crash. Aug 27 16:09:42 home-spb kernel: [148572.258711] EXT4-fs error (device sdc2): ext4_mb_generate_buddy:739: group 4345, 32254 clusters in bitmap, 32258 in gd Aug 27 16:09:42 home-spb kernel: [148572.277591] JBD2: Spotted dirty metadata buffer (dev = sdc2, blocknr = 0). There's a risk of filesystem corruption in case of system crash. Aug 27 16:09:42 home-spb kernel: [148572.278202] EXT4-fs error (device sdc2): ext4_mb_generate_buddy:739: group 4344, 32254 clusters in bitmap, 32258 in gd Aug 27 16:09:42 home-spb kernel: [148572.284760] JBD2: Spotted dirty metadata buffer (dev = sdc2, blocknr = 0). There's a risk of filesystem corruption in case of system crash. Aug 27 16:09:42 home-spb kernel: [148572.291983] EXT4-fs error (device sdc2): ext4_mb_generate_buddy:739: group 9051, 32254 clusters in bitmap, 32258 in gd Aug 27 16:09:42 home-spb kernel: [148572.297495] JBD2: Spotted dirty metadata buffer (dev = sdc2, blocknr = 0). There's a risk of filesystem corruption in case of system crash. Aug 27 16:09:42 home-spb kernel: [148572.297916] EXT4-fs error (device sdc2): ext4_mb_generate_buddy:739: group 9050, 32254 clusters in bitmap, 32258 in gd Aug 27 16:09:42 home-spb kernel: [148572.297940] JBD2: Spotted dirty metadata buffer (dev = sdc2, blocknr = 0). There's a risk of filesystem corruption in case of system crash. Aug 27 16:09:42 home-spb kernel: [148572.303213] EXT4-fs error (device sdc2): ext4_mb_generate_buddy:739: group 4425, 32254 clusters in bitmap, 32258 in gd Aug 27 16:09:42 home-spb kernel: [148572.312127] JBD2: Spotted dirty metadata buffer (dev = sdc2, blocknr = 0). There's a risk of filesystem corruption in case of system crash. Aug 27 16:09:42 home-spb kernel: [148572.312487] EXT4-fs error (device sdc2): ext4_mb_generate_buddy:739: group 4424, 32254 clusters in bitmap, 32258 in gd Aug 27 16:09:42 home-spb kernel: [148572.317858] JBD2: Spotted dirty metadata buffer (dev = sdc2, blocknr = 0). There's a risk of filesystem corruption in case of system crash. Aug 27 16:09:42 home-spb kernel: [148572.322231] EXT4-fs error (device sdc2): ext4_mb_generate_buddy:739: group 4336, 32254 clusters in bitmap, 32258 in gd Aug 27 16:09:42 home-spb kernel: [148572.326250] JBD2: Spotted dirty metadata buffer (dev = sdc2, blocknr = 0). There's a risk of filesystem corruption in case of system crash. Aug 27 16:09:42 home-spb kernel: [148572.326599] EXT4-fs error (device sdc2): ext4_mb_generate_buddy:739: group 4335, 32254 clusters in bitmap, 32258 in gd Aug 27 16:09:42 home-spb kernel: [148572.332397] JBD2: Spotted dirty metadata buffer (dev = sdc2, blocknr = 0). There's a risk of filesystem corruption in case of system crash. Aug 27 16:09:42 home-spb kernel: [148572.341957] EXT4-fs error (device sdc2): ext4_mb_generate_buddy:739: group 5764, 32254 clusters in bitmap, 32258 in gd Aug 27 16:09:42 home-spb kernel: [148572.350709] JBD2: Spotted dirty metadata buffer (dev = sdc2, blocknr = 0). There's a risk of filesystem corruption in case of system crash. Aug 27 16:09:42 home-spb kernel: [148572.351127] EXT4-fs error (device sdc2): ext4_mb_generate_buddy:739: group 5763, 32254 clusters in bitmap, 32258 in gd Aug 27 16:09:42 home-spb kernel: [148572.355916] JBD2: Spotted dirty metadata buffer (dev = sdc2, blocknr = 0). There's a risk of filesystem corruption in case of system crash. Aug 27 16:09:43 home-spb kernel: [148572.401055] EXT4-fs error (device sdc2): ext4_mb_generate_buddy:739: group 10063, 32254 clusters in bitmap, 32258 in gd Aug 27 16:09:43 home-spb kernel: [148572.404357] JBD2: Spotted dirty metadata buffer (dev = sdc2, blocknr = 0). There's a risk of filesystem corruption in case of system crash. Aug 27 16:09:43 home-spb kernel: [148572.414699] EXT4-fs error (device sdc2): ext4_mb_generate_buddy:739: group 10073, 32254 clusters in bitmap, 32258 in gd Aug 27 16:09:43 home-spb kernel: [148572.420411] JBD2: Spotted dirty metadata buffer (dev = sdc2, blocknr = 0). There's a risk of filesystem corruption in case of system crash. Aug 27 16:09:43 home-spb kernel: [148572.493933] EXT4-fs error (device sdc2): ext4_mb_generate_buddy:739: group 9059, 32254 clusters in bitmap, 32258 in gd Aug 27 16:09:43 home-spb kernel: [148572.493956] JBD2: Spotted dirty metadata buffer (dev = sdc2, blocknr = 0). There's a risk of filesystem corruption in case of system crash. One time, machine rebooted (not manually), when I turn it on, it runs fsck on /dev/sdc2 and fix some errors and some files are missing on /dev/sdc2 I'v check /dev/sdc2 for badblocks, it doesn't have it ( using e2fsck -c /dev/sdc2 ) Here is the output of fsck http://pastebin.com/D5LmLVBY What else I can do to understand what's wrong here? BTW for /dev/sdc1 no message like that, in kern.log Linux version: 3.3.0 Distributive: Debian wheezy

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  • please explain my fio results - is O_SYNC|O_DIRECT misbehaving on linux?

    - by Zoltan
    I'm going mad over figuring out what the problem could be with one of our storage boxes. With a simple fio script I'm testing random writes using bs=1M and direct=1. The SSD is a Samsung 840pro attached to an LSI HBA (3Gbit/s ports). This is the result I'm getting under FreeBSD 9.1: WRITE: io=13169MB, aggrb=224743KB/s, minb=224743KB/s, maxb=224743KB/s, mint=60002msec, maxt=60002msec This is regardless of sync being set to 0 or 1. On linux, this is the result with sync=0: WRITE: io=14828MB, aggrb=253060KB/s, minb=253060KB/s, maxb=253060KB/s, mint=60001msec, maxt=60001msec and with sync=1: WRITE: io=6360.0MB, aggrb=108542KB/s, minb=108542KB/s, maxb=108542KB/s, mint=60001msec, maxt=60001msec My understanding is that since I'm operating on the raw block device, O_SYNC should not make any difference - there's no filesystem, any barrier, anything between the writes and the drive itself. Especially with O_DIRECT|O_SYNC set. Any ideas? For reference, here's the fio script I'm testing with: [global] bs=1M ioengine=sync iodepth=4 size=16g direct=1 runtime=60 filename=/dev/sdh sync=1 [rand-write] rw=randwrite stonewall

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  • Do we really need a thousand Linux distributions?

    - by nebukadnezzar
    Pointed from an answer to a (possibly related) question, I came across this graphic, and I'm shocked how many linux distributions currently exist. However, it seems that most of these distributions are forks of already popular distributions with minimal changes, usually limited to themes, wallpapers, buttons, the kind of stuff most people probably wouldn't see as a reason to fork a Linux distribution. Of course, someone will always say "Opensource is also about the freedom of choice", and while I wholeheartedly agree, I do not believe that this is a valid reason to fork an already perfectly working Distribution into a new one, which might possibly result in less security/stability due to smaller group of developers. There's another problem: Those, who want to switch to Linux, are confronted with a neverending list of Linux distributions, and wonder rightfully which they're supposed to chose (infact, I was facing that problem before I've discovered Ubuntu). There might be (very few) valid reasons to fork a distribution: Specializing on a particular topic (FOSS Only, work-related topic (i.e., for a Hospital), etc) An exceptional architecture, that requires a special set of software Use of non-FOSS, propietary technology, and such But even with these points in mind, it would still seem easier to create a subdistribution with the required changes, such as XUbuntu with XFCE4, KUbuntu with KDE4, Fluxbuntu with Fluxbox, etc. So, why exactly do we need so many distributions?

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  • Ubuntu installation error on a windows machine

    - by Rahul
    Was trying to install Ubuntu from a CD on a machine which already has windows on it, choose the option of "Resize IDE1 master (hda) and use freed space" during the "Install the base system" step. After that i get the error- "Unable to install initrd-tools. An error was returned while trying to install the initrd-tools package into the target system. Check /target/var/log/bootstrap.log for details. The problem is one one hand i cannot proceed with the complete installation and on other hand if i remove the CD, am not able to boot windows as it says No bootable device. Would highly appreciate for any recommendations.

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  • western digital caviar black. EXT4-fs error

    - by azat
    Recently I update my HDD on desktop machine, and bought WD Caviar Black. But after I format & copy information to it (using dd), and fix partitions size: I have next errors in kern.log: Aug 27 16:04:35 home-spb kernel: [148265.326264] EXT4-fs error (device sdc2): ext4_mb_generate_buddy:739: group 9054, 32254 clusters in bitmap, 32258 in gd Aug 27 16:07:11 home-spb kernel: [148421.493483] EXT4-fs error (device sdc2): ext4_mb_generate_buddy:739: group 9045, 32254 clusters in bitmap, 32258 in gd Aug 27 16:09:17 home-spb kernel: [148546.481693] EXT4-fs error (device sdc2): ext4_mb_generate_buddy:739: group 10299, 32254 clusters in bitmap, 32258 in gd Aug 27 16:09:17 home-spb kernel: [148546.487147] JBD2: Spotted dirty metadata buffer (dev = sdc2, blocknr = 0). There's a risk of filesystem corruption in case of system crash. Aug 27 16:09:42 home-spb kernel: [148572.258711] EXT4-fs error (device sdc2): ext4_mb_generate_buddy:739: group 4345, 32254 clusters in bitmap, 32258 in gd Aug 27 16:09:42 home-spb kernel: [148572.277591] JBD2: Spotted dirty metadata buffer (dev = sdc2, blocknr = 0). There's a risk of filesystem corruption in case of system crash. Aug 27 16:09:42 home-spb kernel: [148572.278202] EXT4-fs error (device sdc2): ext4_mb_generate_buddy:739: group 4344, 32254 clusters in bitmap, 32258 in gd Aug 27 16:09:42 home-spb kernel: [148572.284760] JBD2: Spotted dirty metadata buffer (dev = sdc2, blocknr = 0). There's a risk of filesystem corruption in case of system crash. Aug 27 16:09:42 home-spb kernel: [148572.291983] EXT4-fs error (device sdc2): ext4_mb_generate_buddy:739: group 9051, 32254 clusters in bitmap, 32258 in gd Aug 27 16:09:42 home-spb kernel: [148572.297495] JBD2: Spotted dirty metadata buffer (dev = sdc2, blocknr = 0). There's a risk of filesystem corruption in case of system crash. Aug 27 16:09:42 home-spb kernel: [148572.297916] EXT4-fs error (device sdc2): ext4_mb_generate_buddy:739: group 9050, 32254 clusters in bitmap, 32258 in gd Aug 27 16:09:42 home-spb kernel: [148572.297940] JBD2: Spotted dirty metadata buffer (dev = sdc2, blocknr = 0). There's a risk of filesystem corruption in case of system crash. Aug 27 16:09:42 home-spb kernel: [148572.303213] EXT4-fs error (device sdc2): ext4_mb_generate_buddy:739: group 4425, 32254 clusters in bitmap, 32258 in gd Aug 27 16:09:42 home-spb kernel: [148572.312127] JBD2: Spotted dirty metadata buffer (dev = sdc2, blocknr = 0). There's a risk of filesystem corruption in case of system crash. Aug 27 16:09:42 home-spb kernel: [148572.312487] EXT4-fs error (device sdc2): ext4_mb_generate_buddy:739: group 4424, 32254 clusters in bitmap, 32258 in gd Aug 27 16:09:42 home-spb kernel: [148572.317858] JBD2: Spotted dirty metadata buffer (dev = sdc2, blocknr = 0). There's a risk of filesystem corruption in case of system crash. Aug 27 16:09:42 home-spb kernel: [148572.322231] EXT4-fs error (device sdc2): ext4_mb_generate_buddy:739: group 4336, 32254 clusters in bitmap, 32258 in gd Aug 27 16:09:42 home-spb kernel: [148572.326250] JBD2: Spotted dirty metadata buffer (dev = sdc2, blocknr = 0). There's a risk of filesystem corruption in case of system crash. Aug 27 16:09:42 home-spb kernel: [148572.326599] EXT4-fs error (device sdc2): ext4_mb_generate_buddy:739: group 4335, 32254 clusters in bitmap, 32258 in gd Aug 27 16:09:42 home-spb kernel: [148572.332397] JBD2: Spotted dirty metadata buffer (dev = sdc2, blocknr = 0). There's a risk of filesystem corruption in case of system crash. Aug 27 16:09:42 home-spb kernel: [148572.341957] EXT4-fs error (device sdc2): ext4_mb_generate_buddy:739: group 5764, 32254 clusters in bitmap, 32258 in gd Aug 27 16:09:42 home-spb kernel: [148572.350709] JBD2: Spotted dirty metadata buffer (dev = sdc2, blocknr = 0). There's a risk of filesystem corruption in case of system crash. Aug 27 16:09:42 home-spb kernel: [148572.351127] EXT4-fs error (device sdc2): ext4_mb_generate_buddy:739: group 5763, 32254 clusters in bitmap, 32258 in gd Aug 27 16:09:42 home-spb kernel: [148572.355916] JBD2: Spotted dirty metadata buffer (dev = sdc2, blocknr = 0). There's a risk of filesystem corruption in case of system crash. Aug 27 16:09:43 home-spb kernel: [148572.401055] EXT4-fs error (device sdc2): ext4_mb_generate_buddy:739: group 10063, 32254 clusters in bitmap, 32258 in gd Aug 27 16:09:43 home-spb kernel: [148572.404357] JBD2: Spotted dirty metadata buffer (dev = sdc2, blocknr = 0). There's a risk of filesystem corruption in case of system crash. Aug 27 16:09:43 home-spb kernel: [148572.414699] EXT4-fs error (device sdc2): ext4_mb_generate_buddy:739: group 10073, 32254 clusters in bitmap, 32258 in gd Aug 27 16:09:43 home-spb kernel: [148572.420411] JBD2: Spotted dirty metadata buffer (dev = sdc2, blocknr = 0). There's a risk of filesystem corruption in case of system crash. Aug 27 16:09:43 home-spb kernel: [148572.493933] EXT4-fs error (device sdc2): ext4_mb_generate_buddy:739: group 9059, 32254 clusters in bitmap, 32258 in gd Aug 27 16:09:43 home-spb kernel: [148572.493956] JBD2: Spotted dirty metadata buffer (dev = sdc2, blocknr = 0). There's a risk of filesystem corruption in case of system crash. One time, machine rebooted (not manually), when I turn it on, it runs fsck on /dev/sdc2 and fix some errors and some files are missing on /dev/sdc2 I'v check /dev/sdc2 for badblocks, it doesn't have it ( using e2fsck -c /dev/sdc2 ) Here is the output of fsck http://pastebin.com/D5LmLVBY What else I can do to understand what's wrong here? BTW for /dev/sdc1 no message like that, in kern.log Linux version: 3.3.0 Distributive: Debian wheezy

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  • Linux Device Driver - what's wrong with my device_read()?

    - by Rob
    My device /dev/my_inc is meant to take a positive integer N represented as an ascii string, and store it. Any read from /dev/my_inc will produce the ascii string representation of N + 1. The problem is that when I cat /dev/my_inc, I only get the first byte of myinc_value output to my shell, even though I have bytes_read == 2 at the end of my loop. /* Read from the device *********************/ static ssize_t device_read(struct file *filp, char *buffer, size_t length, loff_t *offset) { char c; int bytes_read = 0; int value = myinc_value + 1; printk(KERN_INFO "my_inc device_read() called with value %d and msg %s.\n", value, msg); /* No bytes read if pointer to 0 */ if (*msg_ptr == 0) return 0; /* Put the incremented value in msg */ snprintf(msg, MAX_LENGTH, "%d", value); /* Put bytes from msg into user space buffer */ while (length && *msg_ptr) { c = *(msg_ptr++); printk(KERN_INFO "%s device_read() read %c.", DEV_NAME, c); if(put_user(c, buffer++)) return -EFAULT; length--; bytes_read++; } printk("my_inc device_read() returning %d.\n", bytes_read); /* Return bytes copied */ return bytes_read; }

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  • How to find out memory layout of your data structure implementation on Linux 64bit machine

    - by ajay
    In this article, http://cacm.acm.org/magazines/2010/7/95061-youre-doing-it-wrong/fulltext the author talks about the memory layouts of 2 data structures - The Binary Heap and the B-Heap and compares how one has better memory layout than the other. http://deliveryimages.acm.org/10.1145/1790000/1785434/figs/f5.jpg http://deliveryimages.acm.org/10.1145/1790000/1785434/figs/f6.jpg I want to get hands on experience on this. I have an implementation of a N-Ary Tree and I want to find out the memory layout of my data structure. What is the best way to come up with a memory layout like the one in the article? Secondly, I think it is easier to identify the memory layout if it is an array based implementation. If the implementation of a Tree uses pointers then what Tools do we have or what kind of approach is required to map it's memory layout? Thanks!

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  • Simple P2V help from Linux to Windows

    - by Ke.
    I have two OS's installed on different drives in my PC. One linux (Centos 5.4) and one windows 7. Its getting tiresome to constantly have to stop and restart the PC when I want to use either OS. I would very much like to use Windows 7 as my host OS and access my linux OS from within Windows. However, im having trouble deciphering exactly how to do this (many of the articles seem confusing and a bit overkill) From what i have seen its possible to use VMWare converter to convert the physical linux image to a virtual image so that I can use it in windows. As im having problems understanding how this is done, I would really appreciate a step by step guide (for a newbie), or any simple tutorials that you can point me at. Some questions beforehand: 1) My linux image is around 80gb, do i need to take this into consideration? The linux drive is around 180gb in total. All my other drives are NTFS non writeable in linux (as I use them in windows and ntfs is dodgy in linux), so probably not possible to move the image over to my ntfs drives 2) Can I just zip the linux files up somehow and transfer it to windows to create the p2v? 3) Is it possible to do the P2V conversion while I am logged into windows. I can see the actual linux drive loaded in disk manager, but windows doesnt read linux file systems so im confused as to how to access the linux drive if this is possible. 4) Or will i need to do the whole p2v conversion inside linux? Cheers, any help is much appreciated Ke (a confused p2v newbie)

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  • How to add a Linux Partition on FreeBSD

    - by Ömer
    Today I installed FreeBSD 9.0 PPC on my Mac mini G4 with 40GB HDD. During installation, (using the FSBD utility 'gpart') I have allocated a total of about 23GB for FreeBSD leaving 17GB totally free (neither partitioned, nor formatted) for a later Linux installation. Now, when try to install Linux (Ubuntu 10.10 PPC) on the remaining 17GB, the Linux/Ubuntu installer (or Linux's Disk Utility for the same matter) wants presumably a linux partition and when I try to add a (Linux) partition on that area using Linux DU it fails with this message: Error creating partition: helper exited with exit code 1: In part_add_partition: device_file=/dev/hda, start=23363101696, size=16644660224, type= Entering MS-DOS parser (offset=0, size=40007761920) No MSDOS_MAGIC found Exiting MS-DOS parser Entering Apple parser Mac MAGIC found, block_size=512 map_count = 17 Leaving Apple parser Apple partition table detected containing partition table scheme = 2 got it Error: The partition's data region doesn't occupy the entire partition. ped_disk_new() failed Now, I'm trying to add a Linux partition on FreeBSD running on the harddisk. I use seemingly most suitable tool for this job: gpart. Here is the 'gpart show ad0' But it seems unable to add a Linux partition because "man gpart" doesn't list either "Linux Partition" nor anything like Ext2 or Ext3/Ext4. The closest thing to Linux Partition in gpart is "mbr" but it doesn't work: #gpart add -t mbr ado So, how to add properly a Linux Partition on FreeBSD? Thanks.

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  • Simple P2V help from Linux to Windows

    - by Ke
    Hi, I have two OS's installed on different drives in my PC. One linux (Centos 5.4) and one windows 7. Its getting tiresome to constantly have to stop and restart the PC when I want to use either OS. I would very much like to use Windows 7 as my host OS and access my linux OS from within Windows. However, im having trouble deciphering exactly how to do this (many of the articles seem confusing and a bit overkill) From what i have seen its possible to use VMWare converter to convert the physical linux image to a virtual image so that I can use it in windows. As im having problems understanding how this is done, I would really appreciate a step by step guide (for a newbie), or any simple tutorials that you can point me at. Some questions beforehand: 1) My linux image is around 80gb, do i need to take this into consideration? The linux drive is around 180gb in total. All my other drives are NTFS non writeable in linux (as I use them in windows and ntfs is dodgy in linux), so probably not possible to move the image over to my ntfs drives 2) Can I just zip the linux files up somehow and transfer it to windows to create the p2v? 3) Is it possible to do the P2V conversion while I am logged into windows. I can see the actual linux drive loaded in disk manager, but windows doesnt read linux file systems so im confused as to how to access the linux drive if this is possible. 4) Or will i need to do the whole p2v conversion inside linux? Cheers, any help is much appreciated Ke (a confused p2v newbie)

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  • md/raid:md2: cannot start dirty degraded array, kernel panic

    - by nl-x
    After having made use of a remote power switch, my server did not come back online. When I went to the datacenter and reboot the computer on the spot I see the server booting (I see the centos progress bar with running almost all the way to the end) and eventually giving the following messages: md/raid:md2: cannot start dirty degraded array. md/raid:md2: failed to run raid set. md: pers->run() failed ... md/raid:md2: cannot start dirty degraded array. md/raid:md2: failed to run raid set. md: pers->run() failed ... Kernel panic - not syncing: Attempted to kill init! Pid: 1, comm: init not tainted 2.6.32-279.1.1.el6.i686 #1 Call Trace: [<c083bfbc>] ? panic+0x68/0x11c [<c045a501>] ? do_exit+0x741/0x750 [<c045a54c>] ? do_group_exit+0x3c/0xa0 [<c045a5c1>] ? sys_exit_group+0x11/0x20 [<c083eba4>] ? syscall_call+0x7/0xb [<c083007b>] ? cmos_wake_setup+0x62/0x112 The server runs CentOS and has software raid, and I don't have backups of the raid settings. The only backup I have is of /home and the database dumps. (Glad to at least have those though.) Since the server is an old Dell PowerEdge 1750 with no CD-ROM drive, I have no way of booting the machine from a boot disk. I also remember in the past that the server also wouldn't boot from a bootable USB disk. So the only way I know how to boot the server is to go to the datacenter, pick up the server and take it to the office. Screw open the server. Attach a cdrom drive to an IDE slot on the motherboard. And then boot it. I am hoping you guys could help me avoid this. I have looked a bit through the boot options and I found the following boot options. When CentOS is about to boot and interrupt the boot-countdown: CentOS (2.6.32-279.1.1.el63.i686) CentOS Linux (2.6.32-71.29.1.el6.i686) centos (2.6.32-71.el6.i686) I think the first configuration is the default one, because choosing that gets me to the above mentioned kernel panic. The other ones end with something like "Sleeping forever". I can press 'e' to edit boot commands, press 'a' to modify kernel arguments and press 'c' for grub command line. The command line gives a grub prompt. But I have no idea how to get the system to boot without (trying to) access the dirty partitions. What I want to do is off course: - boot the machine - check hard drive for errors - mark the drive as clean

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  • How To Make NVIDIA’s Optimus Work on Linux

    - by Chris Hoffman
    Many new laptops come with NVIDIA’s Optimus technology – the laptop includes both a discrete NVIDIA GPU for gaming power and an onboard Intel GPU for power savings. The notebook switches between the two when necessary. However, this isn’t yet well-supported on Linux. Linus Torvalds had some choice words for NVIDIA regarding Optimus not working on Linux, and NVIDIA is now currently working on official support. However, if you have a laptop with Optimus support, you don’t have to wait for NVIDIA — you can use the Bumblebee project’s solution to enable Optimus on Linux today. Image Credit: Jemimus on Flickr How To Create a Customized Windows 7 Installation Disc With Integrated Updates How to Get Pro Features in Windows Home Versions with Third Party Tools HTG Explains: Is ReadyBoost Worth Using?

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  • HTG Explains: What “Everything Is a File” Means on Linux

    - by Chris Hoffman
    One of the defining features of Linux and other UNIX-like operating systems is that “everything is a file.” This is an oversimplification, but understanding what it means will help you understand how Linux works. Many things on Linux appear in your file system, but they aren’t actually files. They’re special files that represent hardware devices, system information, and other things — including a random number generator. These special files may be located in pseudo or virtual file systems such as /dev, which contains special files that represent devices, and /proc, which contains special files that represent system and process information. How to Banish Duplicate Photos with VisiPic How to Make Your Laptop Choose a Wired Connection Instead of Wireless HTG Explains: What Is Two-Factor Authentication and Should I Be Using It?

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  • Oracle Linux and Oracle VM pricing guide

    - by wcoekaer
    A few days ago someone showed me a pricing guide from a Linux vendor and I was a bit surprised at the complexity of it. Especially when you look at larger servers (4 or 8 sockets) and when adding virtual machine use into the mix. I think we have a very compelling and simple pricing model for both Oracle Linux and Oracle VM. Let me see if I can explain it in 1 page, not 10 pages. This pricing information is publicly available on the Oracle store, I am using the current public list prices. Also keep in mind that this is for customers using non-oracle x86 servers. When a customer purchases an Oracle x86 server, the annual systems support includes full use (all you can eat) of Oracle Linux, Oracle VM and Oracle Solaris (no matter how many VMs you run on that server, in case you deploy guests on a hypervisor). This support level is the equivalent of premier support in the list below. Let's start with Oracle VM (x86) : Oracle VM support subscriptions are per physical server on which you deploy the Oracle VM Server product. (1) Oracle VM Premier Limited - 1- or 2 socket server : $599 per server per year (2) Oracle VM Premier - more than 2 socket server (4, or 8 or whatever more) : $1199 per server per year The above includes the use of Oracle VM Manager and Oracle Enterprise Manager Cloud Control's Virtualization management pack (including self service cloud portal, etc..) 24x7 support, access to bugfixes, updates and new releases. It also includes all options, live migrate, dynamic resource scheduling, high availability, dynamic power management, etc If you want to play with the product, or even use the product without access to support services, the product is freely downloadable from edelivery. Next, Oracle Linux : Oracle Linux support subscriptions are per physical server. If you plan to run Oracle Linux as a guest on Oracle VM, VMWare or Hyper-v, you only have to pay for a single subscription per system, we do not charge per guest or per number of guests. In other words, you can run any number of Oracle Linux guests per physical server and count it as just a single subscription. (1) Oracle Linux Network Support - any number of sockets per server : $119 per server per year Network support does not offer support services. It provides access to the Unbreakable Linux Network and also offers full indemnification for Oracle Linux. (2) Oracle Linux Basic Limited Support - 1- or 2 socket servers : $499 per server per year This subscription provides 24x7 support services, access to the Unbreakable Linux Network and the Oracle Support portal, indemnification, use of Oracle Clusterware for Linux HA and use of Oracle Enterprise Manager Cloud control for Linux OS management. It includes ocfs2 as a clustered filesystem. (3) Oracle Linux Basic Support - more than 2 socket server (4, or 8 or more) : $1199 per server per year This subscription provides 24x7 support services, access to the Unbreakable Linux Network and the Oracle Support portal, indemnification, use of Oracle Clusterware for Linux HA and use of Oracle Enterprise Manager Cloud control for Linux OS management. It includes ocfs2 as a clustered filesystem (4) Oracle Linux Premier Limited Support - 1- or 2 socket servers : $1399 per server per year This subscription provides 24x7 support services, access to the Unbreakable Linux Network and the Oracle Support portal, indemnification, use of Oracle Clusterware for Linux HA and use of Oracle Enterprise Manager Cloud control for Linux OS management, XFS filesystem support. It also offers Oracle Lifetime support, backporting of patches for critical customers in previous versions of package and ksplice zero-downtime updates. (5) Oracle Linux Premier Support - more than 2 socket servers : $2299 per server per year This subscription provides 24x7 support services, access to the Unbreakable Linux Network and the Oracle Support portal, indemnification, use of Oracle Clusterware for Linux HA and use of Oracle Enterprise Manager Cloud control for Linux OS management, XFS filesystem support. It also offers Oracle Lifetime support, backporting of patches for critical customers in previous versions of package and ksplice zero-downtime updates. (6) Freely available Oracle Linux - any number of sockets You can freely download Oracle Linux, install it on any number of servers and use it for any reason, without support, without right to use of these extra features like Oracle Clusterware or ksplice, without indemnification. However, you do have full access to all errata as well. Need support? then use options (1)..(5) So that's it. Count number of 2 socket boxes, more than 2 socket boxes, decide on basic or premier support level and you are done. You don't have to worry about different levels based on how many virtual instance you deploy or want to deploy. A very simple menu of choices. We offer, inclusive, Linux OS clusterware, Linux OS Management, provisioning and monitoring, cluster filesystem (ocfs), high performance filesystem (xfs), dtrace, ksplice, ofed (infiniband stack for high performance networking). No separate add-on menus. NOTE : socket/cpu can have any number of cores. So whether you have a 4,6,8,10 or 12 core CPU doesn't matter, we count the number of physical CPUs.

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  • How to Share Files Between User Accounts on Windows, Linux, or OS X

    - by Chris Hoffman
    Your operating system provides each user account with its own folders when you set up several different user accounts on the same computer. Shared folders allow you to share files between user accounts. This process works similarly on Windows, Linux, and Mac OS X. These are all powerful multi-user operating systems with similar folder and file permission systems. Windows On Windows, the “Public” user’s folders are accessible to all users. You’ll find this folder under C:\Users\Public by default. Files you place in any of these folders will be accessible to other users, so it’s a good way to share music, videos, and other types of files between users on the same computer. Windows even adds these folders to each user’s libraries by default. For example, a user’s Music library contains the user’s music folder under C:\Users\NAME\as well as the public music folder under C:\Users\Public\. This makes it easy for each user to find the shared, public files. It also makes it easy to make a file public — just drag and drop a file from the user-specific folder to the public folder in the library. Libraries are hidden by default on Windows 8.1, so you’ll have to unhide them to do this. These Public folders can also be used to share folders publically on the local network. You’ll find the Public folder sharing option under Advanced sharing settings in the Network and Sharing Control Panel. You could also choose to make any folder shared between users, but this will require messing with folder permissions in Windows. To do this, right-click a folder anywhere in the file system and select Properties. Use the options on the Security tab to change the folder’s permissions and make it accessible to different user accounts. You’ll need administrator access to do this. Linux This is a bit more complicated on Linux, as typical Linux distributions don’t come with a special user folder all users have read-write access to. The Public folder on Ubuntu is for sharing files between computers on a network. You can use Linux’s permissions system to give other user accounts read or read-write access to specific folders. The process below is for Ubuntu 14.04, but it should be identical on any other Linux distribution using GNOME with the Nautilus file manager. It should be similar for other desktop environments, too. Locate the folder you want to make accessible to other users, right-click it, and select Properties. On the Permissions tab, give “Others” the “Create and delete files” permission. Click the Change Permissions for Enclosed Files button and give “Others” the “Read and write” and “Create and Delete Files” permissions. Other users on the same computer will then have read and write access to your folder. They’ll find it under /home/YOURNAME/folder under Computer. To speed things up, they can create a link or bookmark to the folder so they always have easy access to it. Mac OS X Mac OS X creates a special Shared folder that all user accounts have access to. This folder is intended for sharing files between different user accounts. It’s located at /Users/Shared. To access it, open the Finder and click Go > Computer. Navigate to Macintosh HD > Users > Shared. Files you place in this folder can be accessed by any user account on your Mac. These tricks are useful if you’re sharing a computer with other people and you all have your own user accounts — maybe your kids have their own limited accounts. You can share a music library, downloads folder, picture archive, videos, documents, or anything else you like without keeping duplicate copies.

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  • Getting a solid understanding of Linux fundamentals

    - by JoshEarl
    I'm delving into the Linux world again as a diversion from my Microsoft-centric day job, and every time I tackle a new project I find it a frustrating exercise in trial and error. One thing that I always try to do when learning something new is figure out what the big pieces are and how they work together. I haven't yet come across a resource that explains Linux at this level. Resources seem to be either aimed at the barely computer literate crowd (Linux doesn't bite. Promise!) or the just compile the kernel and make your own distro crowd. I'm looking for a "JavaScript: The Good Parts" type of road map that doesn't necessarily answer all my questions so much as help me understand what questions I need to be asking. Any suggestions?

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  • The best choice of linux file system and software that can be accesed from Windows

    - by Florin
    I am curently having ubuntu and win 7 dual boot and I want to delete my windows 7 and format all my partitions to use a linux file system. But I want to leave a door open in case I have any problems with linux, to be able to acces my linux file system with windows. I know that there are programs that can give you read-write acces to a ext2/3/4 FS (I tested none). I need advice in choosing the right FS, what are the diferences between ext 2/3/4 and what is the best software to do that.

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  • Developing for iOS on Linux

    - by Jay
    I am looking for an engine or library to develop a game for iOS on Linux. High level, low level, GUI, no GUI, does not matter too much. I am really looking for anything. I'm not actually talking about deploying to iOS from Linux or anything like. I just want to do the bulk of the work on Linux, with minimal changes required to run it on iOS. Edit: YES, I do have access to a Mac, but it is limited. So I want to be able to work on the project on my regular Ubuntu box. Also, I am in the paid developer program, so I can deploy to iOS devices from the Mac.

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