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  • Redirection of outbound UDP port NTP.

    - by pboin
    For my residential service, I changed ISPs to Zoom/Armstrong. Just after that, my NTP daemons stopped working. I dug deep and diagnosed the problem: Unprivileged ports are getting out. When i run 'ntpdate' for example, I go out on a high, unprivleged port, and get a response on UDP 123. That's fine. The 'ntpd' daemon though, expects to go out on 123 and get its reply there as well. This must be a common problem, because it's directly addressed in the NTP troubleshooting guide. Just to see what would happen, I wrote a detailed email to the general support address at Armstrong. They replied almost immediately with a complete technical answer! They have everything <1024 blocked, except for a few ports to support outbound VPN. So, the question: Can I use IPtables to essentially re-write my outbound UDP 123 up to 2123 or something like that? If I do, does there need to be a corresponding 2123-123 rule to translate the reply? This seems like NAT, but with ports, not addresses. True, I could run ntpdate from cron, but that loses all of the adjustment smarts of NTP.

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  • Running multiple copies of openssh-server (sshd) on Ubuntu

    - by cecilkorik
    I may be attacking this problem the wrong way, if so let me know. I have a server which is available through SSH from both the public internet and the local LAN. I would like to have two very different security policies for each, by running two copies of sshd with two different sshd_config files each on a different port. Some of the things I'd like to change is to allow password or public-key authentication on the LAN, but public-key only from the internet. All (real) users could login from the LAN side, but only certain authorized users would be individually whitelisted to login through the internet. As far as I can tell this requires having two different SSH daemons running on different ports with different sshd_configs. I am fine with the different ports part, I can easily forward port 22 to any port I want through my firewall. So my question is what is the best way to actually START the second sshd under Ubuntu 10.04 LTS. Is there a recommended way to do something like this? Surely I am not the first person with this sort of need. I have a bit of experience with upstart, and I can manually hack the second sshd into /etc/init/ssh.conf I suppose but I'm not sure if that will get overwritten by the package. However I do it, It's important to ensure both sshd processes always get restarted after any automatic or manual upgrade of the openssh-server package. Thanks in advance.

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  • How to set up mysql storage for certain rsyslog input matches?

    - by ylluminate
    I'm draining various logs from Heroku to an rsyslog linux (ubuntu) server and am starting to have a little more to bite off than I can chew in terms of working with my log histories. I am needing to be able drill back in time based on more flexible details and more flexible access than what the standard syslog file(s) provide. I'm thinking that logging to mysql may be the correct approach, but how do I set this up such that it pulls only certain log entries into a table based on an identified? For example, I see a long hex string identifying each log entry from a certain Heroku app instance. I assume that I can just pipe those into the mysql socket vs ALL rsyslog input into mysql... Could someone please direct me to a resource that can walk me through the process of setting something like this up or simply provide some details that can help? I have 15+ years of Unix experience so I just need some nudging in the right direction as I've not really done a tremendous amount of work with syslog daemons previously in terms of pooling various servers into one. Additionally, I'd be interested in any log review tools that could make drilling through log arrangements like this more handy for developers.

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  • Terratec Cinergy Hybrid T USB XS is not recognized anymore on Mac OS X

    - by Gabble
    I have used Terratec Cinergy Hybrid T USB XS for years now, alongside with Elgato EyeTV software. I am a happy and completely satisfied user! Since a couple of weeks the USB sitck stopped working on my MacPro1,1 (OS version 10.6.3): EyeTV does not see any device attached, and actually, the green led on the stick stays off. It is not a USB port fault: I have unplugged any other USB/Firewire device and tried with different USB ports, to no avail (any other USB devices work as expected on any port) I have completely uninstalled EyeTV software, including preferences and system daemons/extensions, rebooted and reinstalled the latest EyeTV. No way. Reset the PRAM. Nope. Checked the Apple System Profiler - USB: No device attached, The MacPro does not see it at all. I need to say that: a) The device worked as a charm even with the latest OS 10.6.x (so it's not a OS upgrade cause). b) I have plugged the Terratec Cinergy Hybrid T USB XS to my MacBook5,1 where EyeTV is not installed and was never installed: The green led on the stick turns on, the growl bubble pops up, and the device is perfectly recognized by the system. Apple System Profiler says (sorry, Italian language): Cinergy Hybrid T USB XS (2882): ID prodotto: 0x005e ID fornitore: 0x0ccd Versione: 1.10 Numero di serie: 061102005755 Velocità: Fino a 12 Mb/sec Produttore: TerraTec Electronic GmbH ID posizione: 0x04100000 Corrente disponibile (mA): 500 Corrente necessaria (mA): 500 At this point I am pretty sure the Terratec stick is not damaged and there is something wrong with my MacPro. I kindly ask you: Is there a way to force my MacPro recognize the USB device? What can I check? Is there something that caches USB connection that can be reset? A OS reinstall would be the very last resort for me. Thanks in advance for any help you will offer!

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  • Arch Linux: eth0 no carrier - network fails at boot

    - by user905686
    The problem My computer is connected to a network where dhcp is required. So my network configuration in /etc/rc.conf looks like interface=eth0 address= netmask= broadcast= gateway= My deamons are DAEMONS=(!hwclock syslog-ng network netfs crond ntpd) With this configuration, Arch hangs at boot a long time at "Network" (Still it says "[done]", but after boot I have no connection). I found out two workaround: Workaround 1 remove network from deamons run mii-tool --reset eth0 and dhcpcd eth0 after boot (somehow it does not work when placing these commands in /etc/rc.local. Then dhcp work very quickly (because of the reset!). Before executing the first command, ip link show eth0 has "NO CARRIER" in output. Afterwards, it doesn´t. (Also, mii-tool first shows "no link", afterwards eth0: 10 Mbit, half duplex, link ok. Workaround 2 Change network configuration to interface=eth0 address=x.y.z.21 netmask=255.255.255.0 broadcast=xxx.y.z.255 gateway=x.y.z.254 whereas x, y, z build the specific adresses of the network (Though dhcp is used, I get a static ip). Add the commands mii-tool --reset eth0 and dhcpcd eth0 to /etc/rc.local Now network starts quickly at boot (though I don´t know if successfully), the commands in /etc/rc.local are executed and the connection is fine after login. What to do? So the problem seems to be that dhcpcd stucks at "wating for carrier" or sth. I do not like the workaround, because some deamons need network (though they seem to start). What can I do to have eth0 ready for dhcp at boot? Or is there another problem?

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  • How to organize deployment process in Chef-controlled environment?

    - by Alex
    I have a web Linux-based infrastructure which consists of 15 virtual machines and over 50 various services. It is fully controlled by Chef. Most of the services are developed internally. Basically the current deployment process is triggered by a shell script. A build system (a mix of Python and shell scripts) packages the services as .deb files and puts these packages into a repo. It runs apt-get update on all 15 nodes then because the standard Chef apt cookbook only runs apt-get once per day and we definitely do not want to run apt-get update unconditionally on each chef-client wake. The build system restarts chef-client daemons on all 15 nodes finally (we need this step because of pull Chef nature). The current process has a number of drawbacks we want to address. First off, it is asynchronous because the deployment script does not check chef-client logs after restart so we don't even know if the deployment was successful. It does not even wait for Chef clients to complete the cycle. Second, we definitely do not want to force chef-client restarts on all nodes because we usually deploy only a small number of packages. And third, I am not quite sure using chef-client for deployment is legitimate, probably we are just doing it wrong from the start. Please share your thoughts/experience.

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  • Openbsd init script for ssh VPN tunnel

    - by manthis
    I have a server hosting SSH tunnels and Openbsd 4.5 clients connecting to it. Things work just fine but I am in the need of automating the connection from the client to the server. So that if the client is accidentally rebooted, then the connection initiates unattended. So it should be as straight forward as to include the ssh connection in an init script. However I have miserably failed to do so by including it to /etc/rc.local, which is the file I usually do this sort of things in. Right now I am using autossh to also restart the connection if necessary and the script that I put on /etc/rc.local follows: #!/bin/sh # # Example script to start up tunnel with autossh. # # This script will tunnel 2200 from the remote host # to 22 on the local host. On remote host do: # ssh -p 2200 localhost # # $Id: autossh.host,v 1.6 2004/01/24 05:53:09 harding Exp $ # ID=root HOST=example.com #AUTOSSH_POLL=600 #AUTOSSH_PORT=20000 #AUTOSSH_GATETIME=30 #AUTOSSH_LOGFILE=$HOST.log #AUTOSSH_DEBUG=yes #AUTOSSH_PATH=/usr/local/bin/ssh export AUTOSSH_POLL AUTOSSH_LOGFILE AUTOSSH_DEBUG AUTOSSH_PATH AUTOSSH_GATETIME AUTOSSH_PORT autossh -2 -f -M 20000 ${ID}@${HOST} The script detaches just fine when run manually so I just include it on /etc/rc.local as echo -n 'starting local daemons:' if [ -x /usr/local/sbin/autossh.sh ]; then echo -n 'ssh tunnel' /usr/local/sbin/autossh.sh fi echo '.' I have also tried calling it from /etc/hostname.tun0 in case there may be issues with /etc/rc.local not being called at the right time when network connections are ready, so I would use: inet 10.254.254.2 255.255.255.252 10.254.254.1 !/usr/local/sbin/autossh.sh Your input is highly appreciated.

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  • Large, high performance object or key/value store for HTTP serving on Linux

    - by Tommy
    I have a service that serves images to end users at a very high rate using plain HTTP. The images vary between 4 and 64kbytes, and there are 1.300.000.000 of them in total. The dataset is about 30TiB in size and changes (new objects, updates, deletes) make out less than 1% of the requests. The number of requests pr. second vary from 240 to 9000 and is dispersed pretty much all over, with few objects being especially "hot". As of now, these images are files on a ext3 filesystem distributed read only across a large amount of mid range servers. This poses several problems: Using a fileysystem is very inefficient since the metadata size is large, the inode/dentry cache is volatile on linux and some daemons tend to stat()/readdir() it's way through the directory structure, which in my case becomes very expensive. Updating the dataset is very time consuming and requires remounting between set A and B. The only reasonable handling is operating on the block device for backup, copying, etc. What I would like is a deamon that: speaks HTTP (get, put, delete and perhaps update) stores data it in an efficient structure. The index should remain in memory, and considering the amount of objects, the overhead must be small. The software should be able to handle massive connections with slow (if any) time needed to ramp up. Index should be read in memory at startup. Statistics would be nice, but not mandatory. I have experimented a bit with riak, redis, mongodb, kyoto and varnish with persistent storage, but I haven't had the chance to dig in really deep yet.

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  • Redirection of outbound UDP port.

    - by pboin
    For my residential service, I changed ISPs to Zoom/Armstrong. Just after that, my NTP daemons stopped working. I dug deep and diagnosed the problem: Unprivileged ports are getting out. When i run 'ntpdate' for example, I go out on a high, unprivleged port, and get a response on UDP 123. That's fine. The 'ntpd' daemon though, expects to go out on 123 and get its reply there as well. This must be a common problem, because it's directly addressed in the NTP troubleshooting guide. Just to see what would happen, I wrote a detailed email to the general support address at Armstrong. They replied almost immediately with a complete technical answer! They have everything <1024 blocked, except for a few ports to support outbound VPN. So, the question: Can I use IPtables to essentially re-write my outbound UDP 123 up to 2123 or something like that? If I do, does there need to be a corresponding 2123-123 rule to translate the reply? This seems like NAT, but with ports, not addresses. I tried, but can't seem to get iptables to do what I want. I'm not sure if it's my lack of skill, or if I'm trying the wrong solution. True, I could run ntpdate from cron, but that loses all of the adjustment smarts of NTP.

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  • Partitioning of Ubuntu server which will use OpenVZ and encrypted partitions (unlocked through SSH l

    - by DeletedAccount
    Hi, I'm about to install a server. Some context: My HDD is 1 TB and I have 2 GB RAM Ubuntu Server Lucid Lynx AMD 64 I will use OpenVZ and have most functionality separated into containers. To support disk quotas I need to use ext3 (not ext4) for the container partition. Each time I reboot the server I want to be forced to login through SSH and mount the encrypted partitions by typing my password (if someone steals the server, no critical data should be available). I want to have as much as possible encrypted. Yet I want to be able to login through SSH as I don't have a monitor or keyboard at the server. I am not sure how big I need my partitions to be. Being able to resize them later would be nice. I guess it implies using LVM? But the manual partition mount using SSH is also very important (in fact it's more important, if I have to pick one). How do you recommend that I partition the HDD? If I have daemons which needs the encrypted partitions, will they fail and can I just restart them after mounting the needed partitions?

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  • Ubuntu Server 12 not spawning a serial ttyS0 when running on Xen

    - by segfaultreloaded
    I have this problem on more than one host, so the specific hardware is not an issue. Bare metal Ubuntu 12 is not creating a login process on the only serial port, in the default configuration. The serial port works correctly with the firmware. It works correctly with Grub2. I have even connected the serial line to 2 different external client boxes, so the problem is neither the hardware nor the remote client. When finally booted, the system fails to create the login process. root@xenpro3:~# ps ax | grep tty 1229 tty4 Ss+ 0:00 /sbin/getty -8 38400 tty4 1233 tty5 Ss+ 0:00 /sbin/getty -8 38400 tty5 1239 tty2 Ss+ 0:00 /sbin/getty -8 38400 tty2 1241 tty3 Ss+ 0:00 /sbin/getty -8 38400 tty3 1245 tty6 Ss+ 0:00 /sbin/getty -8 38400 tty6 1403 tty1 Ss+ 0:00 /sbin/getty -8 38400 tty1 1996 pts/0 S+ 0:00 grep --color=auto tty root@xenpro3:~# dmesg | grep tty [ 0.000000] Command line: BOOT_IMAGE=/vmlinuz-3.2.0-30-generic root=/dev/mapper/xenpro3-root ro console=ttyS0,115200n8 [ 0.000000] Kernel command line: BOOT_IMAGE=/vmlinuz-3.2.0-30-generic root=/dev/mapper/xenpro3-root ro console=ttyS0,115200n8 [ 0.000000] console [ttyS0] enabled [ 2.160986] serial8250: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A [ 2.203396] serial8250: ttyS1 at I/O 0x2f8 (irq = 3) is a 16550A [ 2.263296] 00:08: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A [ 2.323102] 00:09: ttyS1 at I/O 0x2f8 (irq = 3) is a 16550A root@xenpro3:~# uname -a Linux xenpro3 3.2.0-30-generic #48-Ubuntu SMP Fri Aug 24 16:52:48 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux root@xenpro3:~# I have tried putting a ttyS0.conf file in /etc/initab, which solves the problem bare metal but I still cannot get the serial port to work when booting Ubuntu on top of Xen, as domain 0. My serial line output looks like this, when booting Xen /dev/ttyS0 at 0x03f8 (irq = 4) is a 16550A * Exporting directories for NFS kernel daemon... [ OK ] * Starting NFS kernel daemon [ OK ] SSL tunnels disabled, see /etc/default/stunnel4 [ 18.654627] XENBUS: Unable to read cpu state [ 18.659631] XENBUS: Unable to read cpu state [ 18.664398] XENBUS: Unable to read cpu state [ 18.669248] XENBUS: Unable to read cpu state * Starting Xen daemons [ OK ] mountall: Disconnected from Plymouth At this point, the serial line is no longer connected to a process. Xen itself is running just fine. Dmesg gives me a long list of [ 120.236841] init: ttyS0 main process ended, respawning [ 120.239717] ttyS0: LSR safety check engaged! [ 130.240265] init: ttyS0 main process (1631) terminated with status 1 [ 130.240294] init: ttyS0 main process ended, respawning [ 130.242970] ttyS0: LSR safety check engaged! which is no surprise because I see root@xenpro3:~# ls -l /dev/ttyS? crw-rw---- 1 root tty 4, 64 Nov 7 14:04 /dev/ttyS0 crw-rw---- 1 root dialout 4, 65 Nov 7 14:04 /dev/ttyS1 crw-rw---- 1 root dialout 4, 66 Nov 7 14:04 /dev/ttyS2 crw-rw---- 1 root dialout 4, 67 Nov 7 14:04 /dev/ttyS3 crw-rw---- 1 root dialout 4, 68 Nov 7 14:04 /dev/ttyS4 crw-rw---- 1 root dialout 4, 69 Nov 7 14:04 /dev/ttyS5 crw-rw---- 1 root dialout 4, 70 Nov 7 14:04 /dev/ttyS6 crw-rw---- 1 root dialout 4, 71 Nov 7 14:04 /dev/ttyS7 crw-rw---- 1 root dialout 4, 72 Nov 7 14:04 /dev/ttyS8 crw-rw---- 1 root dialout 4, 73 Nov 7 14:04 /dev/ttyS9 If I manually change the group of /dev/ttyS0 to dialout, it gets changed back. I have made no changes to the default udev rules, so I cannot see where this problem is coming from. Sincerely, John

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  • ArchBeat Link-o-Rama Top 10 for September 9-15, 2012

    - by Bob Rhubart
    The Top 10 most-viewed items shared on the OTN ArchBeat Facebook page for the week of September 9-15, 2017. 15 Lessons from 15 Years as a Software Architect | Ingo Rammer In this presentation from the GOTO Conference in Copenhagen, Ingo Rammer shares 15 tips regarding people, complexity and technology that he learned doing software architecture for 15 years. Attend OTN Architect Day – by Architects, for Architects – October 25 You won't need 3D glasses to take in these live presentations (8 sessions, two tracks) on Cloud computing, SOA, and engineered systems. And the ticket price is: Zero. Nothing. Absolutely free. Register now for Oracle Technology Network Architect Day in Los Angeles. Thursday October 25, 2012, 8:00 a.m. – 5:00 p.m. Sofitel Los Angeles , 8555 Beverly Boulevard , Los Angeles, CA 90048. Cloud API and service designers, stop thinking small | Cloud Computing - InfoWorld "The focus must shift away from fine-grained APIs that provide some type of primitive service, such as pushing data to a block of storage or perhaps making a request to a cloud-rooted database," says InfoWorld's David Linthicum. "To go beyond primitives, you must understand how these services should be used in a much larger architectural context. In other words, you need to understand how businesses will employ these services to form real workplace solutions—inside and outside the enterprise." Adding a runtime picker to a taskflow parameter in WebCenter | Yannick Ongena Oracle ACE Yannick Ongena shows how to create an Oracle WebCenter popup to allow users to "select items or do more complex things." Oracle IAM 11g R2 docs are now available "One of the great things about the new doc set is the inclusion of ePub files," says Fusion Middleware A-Team blogger Chris Johnson. "This means that if you have an iPad you can load up the doc library onto that and read the docs on the couch." Setting up a local Yum Server using the Exalogic ZFS Storage Appliance | Donald A concise technical post from the man named Donald. What's New in Oracle VM VirtualBox 4.2? | The Fat Bloke Sings "One of the trends we've seen is that as the average host platform becomes more powerful, our users are consistently running more and more vm's," says The Fat Bloke. "Some of our users have large libraries of vm's of various vintages, whilst others have groups of vm's that are run together as an assembly of the various tiers in a multi-tiered software solution, for example, a database tier, middleware tier, and front-ends." The new VirtualBox release, a year in the making, addresses the needs of these users, he explains. Configuring Oracle Business Intelligence 11g MDS XML Source Control Management with Git Version Control | Christian Screen Oracle ACE Christian Screen developed this tutorial for those interested in learning how to configure the Oracle Business Intelligence 11g (11.1.1.6) metadata repository for development using the new MDS XML source control management functionality. Identity and Access Management at Oracle Open World 2012 | Brian Eidelman Fusion Middleware A-Team blogger Brian Eideleman highlights three Oracle Openworld sessions that will put Identity and Access Management in the spotlight, and shares a link to the "Focus On: Identity Management" document, a comprehensive listing of Openworld activities also dealing with IM. Starting and stopping WebLogic automatically using Upstart | Chris Johnson "In Ubuntu, RedHat and Oracle Linux there's a new flavor of init called Upstart that all the kids are using," says Oracle Fusion Middleware A-Team member Chris Johnson. "It's the new hotness when it comes to making programs into daemons and wiring them to start and stop at appropriate times." Thought for the Day "The purpose of software engineering is to control complexity, not to create it." — Pamela Zave Source: SoftwareQuotes.com

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  • ACL architechture for a Software As a service in Spring 3.0

    - by geoaxis
    I am making a software as a service using Spring 3.0 (Spring MVC, Spring Security, Spring Roo, Hibernate) I have to come up with a flexible access control list mechanism.I have three different kinds of users System (who can do any thing to the system, includes admin and internal daemons) Operations (who can add and delete users, organizations, and do maintenance work on behalf of users and organizations) End Users (they belong to one or more organization, for each organization, the user can have one or more roles, like being organization admin, or organization read-only member) (role like orgadmin can also add users for that organization) Now my question is, how should i model the entity of User? If I just take the End User, it can belong to one or more organizations, so each user can contain a set of references to its organizations. But how do we model the users role for each organization, So for example User UX belongs to organizations og1, og2 and og3, and for og1 he is both orgadmin, and org-read-only-user, where as for og2 he is only orgadmin and for og3 he is only org-read-only-user I have the possibility of making each user belong to one organization alone, but that's making the system bounded and I don't like that idea (although i would still satisfy the requirement) If you have a better extensible ACL architecture, please suggest it. Since its a software as a service, one would expect that alot of different organizations would be part if the same system. I had one concern that it is not a good idea to keep og1 and og2 data on the same DB (if og1 decides to spawn a 100 reports on the system, og2 should not suffer) But that is some thing advanced for now and is not directly related to ACL but to the physical distribution of data and setup of services based on those ACLs This is a community Wiki question, please correct any thing which you wish to do so. Thanks

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  • How to architect Rails site that can be edited while running?

    - by Chris Kimpton
    Hi, I am writing a Rails app that "scrapes/navigates" some other websites and webservices for content. I am using Mechanize and Savon to do the heavylifting. But given the dynamic nature of the web, I'd like to make my calls to these editable by the admin users of the site - rather than requiring me to release a new version of the site. The actual scraping thread happens async to the website, using the daemons gem. My requirements are: Thinking that the scraping/webservice calling code is quite simple, the easiest route is to make the whole class editable by the admins. Keep a history of the scraping code - so that we can fairly easily revert if we introduce a problem. Initially use the code from the file system, but as soon as thats been edited and stored somewhere, to use that code instead. I am thinking my options are: Store the code in the db (with a history table for the old versions) Store the code in a private git repo somewhere and access that for the history/latest versions. I am thinking the git route might be easiest, given its raison d'etre is to track file history... But perhaps there is a gem/plugin that does all this for me, out of the box? Thanks in advance for any tips/advice. ~chris

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  • Workling processes multiplying uncontrolably

    - by adam
    Hello there. We have a rails app running on passenger and we background process some tasks using a combination of RabbitMQ and Workling. The workling's worker process is started using the script/workling_client command. There is always only one worker process started, and the script/workling_client has a :multiple => false options, thus allowing only one instance. But sometimes, under mysterious circumstances which I haven't been able to track down, more worklings spawn up. If I let the system run for some time, more and more worklings appear. I'm not sure if these rogue worklings cause any problems, but it is still unsettling not to know why is it happening. We are using Monit to monitor the workling process. So if it dies, it will spawn it up again. But this still does not explain how come there are suddenly more than one of them. So my question is: does anyone know what can be cause of this and how to make it stop? Is it possible that workling sometimes dies by itself, without deleting it's pid file? Could there be something wrong with the Daemons gem workling_client is build upon?

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  • ACL architechture for a Software As a service in Sprgin 3.0

    - by geoaxis
    I am making a software as a service using Spring 3.0 (Spring MVC, Spring Security, Spring Roo, Hibernate) I have to come up with a flexible access control list mechanism.I have three different kinds of users System (who can do any thing to the system, includes admin and internal daemons) Operations (who can add and delete users, organizations, and do maintenance work on behalf of users and organizations) End Users (they belong to one or more organization, for each organization, the user can have one or more roles, like being organization admin, or organization read-only member) (role like orgadmin can also add users for that organization) Now my question is, how should i model the entity of User? If I just take the End User, it can belong to one or more organizations, so each user can contain a set of references to its organizations. But how do we model the users role for each organization, So for example User UX belongs to organizations og1, og2 and og3, and for og1 he is both orgadmin, and org-read-only-user, where as for og2 he is only orgadmin and for og3 he is only org-read-only-user I have the possibility of making each user belong to one organization alone, but that's making the system bounded and I don't like that idea (although i would still satisfy the requirement) If you have a better extensible ACL architecture, please suggest it. Since its a software as a service, one would expect that alot of different organizations would be part if the same system. I had one concern that it is not a good idea to keep og1 and og2 data on the same DB (if og1 decides to spawn a 100 reports on the system, og2 should not suffer) But that is some thing advanced for now and is not directly related to ACL but to the physical distribution of data and setup of services based on those ACLs This is a community Wiki question, please correct any thing which you wish to do so. Thanks

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  • Python, Ruby, and C#: Use cases?

    - by thaorius
    Hi everyone. For as long as I can remember, I've always had a "favorite" language, which I use for most projects, until, for some particular reason, there is no way/point on using it for project XYZ. At that point, I find myself rusty (and sometimes outdated) on other languages+libraries+toolchains. So I decided, I would just use some languages/libs/tools for some things, and some for other, effectively keeping them fresh (there would obviously be exceptions, I'm not looking for an arbitrary rule set, but some guidelines). I wanted an opinion on what would be your standard use cases (new projects) for Python, Ruby, and C# (Mono). At the moment, I have time like this:Languages: C#: Mid-Large Sized Projects (mainly server-side daemons) High Performance (I hardly ever need C's performance, but Python just doesn't cut it) Relatively Low Footprint (vs the JVM, for example) Ruby: Web Applications Python: General Use Scripts (automation, system config, etc) Small-Mid Sized Projects Prototyping Web Applications About Ruby, I have no idea what to use it for that I can't use Python for (specially considering Python is more easily found installed by default). And I like both languages (though I'm really new to Ruby), which makes things even worse. As for C#, I have not used a Windows powered computer in a few years, I don't make things for Windows computers, and I don't mind waiting for Mono to implement some new features. That being said, I haven't found many people on the internet using it for server-sided *nix programming (not web related). I would appreciate some insight on this too. Thanks for your time.

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  • Ubuntu server or Debian server (to run C++ apps developed on Ubuntu)

    - by skyeagle
    I have written a number of C++ server side daemons for my website, using my Ubuntu 9.10 dev machine. I am now about to venture out to look for a hosting provider etc. This is my problem: I have read on many posts (admittedly old posts) that Debian server is much more robust than Ubuntu server - is this till the case?. In particular, I am constantly "raising elephants" with my Ubuntu 9.10 - this is "ok" for home use, but for a website server, I would not be so forgiving. Also, there seems to be a new "patch" every few weeks - which I would not like on a server (I want to leave the server well alone, and let it get on with its business of serving pages). So in this instance Debian looks a more attractive proposition. I am worried that the C++ apps I have developed on Ubuntu may not be binary compatable with Debian (or I may need to install additional libraries/packages etc to get things to work), and I have zero experience with Debian. Additionally, I dont want to be grappling with the learning curve associated with a new OS, whilst trying to launch a new web site (I am assuming Debian UI is quite different from Ubuntu). In this case, the maxim "the devil you know is better than the one you dont", seems appropriate - and I find Ubuntu a more attractive proposition (atleast I know my apps will run without any probs etc). Can anyone provide some rational advice (based on actual experience), to help me decide which route to take - given the two (conflicting) trains of thought outlined above?

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  • Help me with the simplest program for "Trusted" application

    - by idazuwaika
    Hi, I hope anyone from the large community here can help me write the simplest "Trusted" program that I can expand from. I'm using Ubuntu Linux 9.04, with TPM emulator 0.60 from Mario Strasser (http://tpm-emulator.berlios.de/). I have installed the emulator and Trousers, and can successfully run programs from tpm-tools after running tpmd and tcsd daemons. I hope to start developing my application, but I have problems compiling the code below. #include <trousers/tss.h> #include <trousers/trousers.h> #include <stdio.h> TSS_HCONTEXT hContext; int main() { Tspi_Context_Create(&hContext); Tspi_Context_Close(hContext); return 0; } After trying to compile with g++ tpm.cpp -o tpmexe I receive errors undefined reference to 'Tspi_Context_Create' undefined reference to 'Tspi_Context_Close' What do I have to #include to successfully compile this? Is there anything that I miss? I'm familiar with C, but not exactly so with Linux/Unix programming environment. ps: I am a part time student in Master in Information Security programme. My involvement with programming has been largely for academic purposes.

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  • Postfix SMTP auth not working with virtual mailboxes + SASL + Courier userdb

    - by Greg K
    So I've read a variety of tutorials and how-to's and I'm struggling to make sense of how to get SMTP auth working with virtual mailboxes in Postfix. I used this Ubuntu tutorial to get set up. I'm using Courier-IMAP and POP3 for reading mail which seems to be working without issue. However, the credentials used to read a mailbox are not working for SMTP. I can see from /var/log/auth.log that PAM is being used, does this require a UNIX user account to work? As I'm using virtual mailboxes to avoid creating user accounts. li305-246 saslauthd[22856]: DEBUG: auth_pam: pam_authenticate failed: Authentication failure li305-246 saslauthd[22856]: do_auth : auth failure: [user=fred] [service=smtp] [realm=] [mech=pam] [reason=PAM auth error] /var/log/mail.log li305-246 postfix/smtpd[27091]: setting up TLS connection from mail-pb0-f43.google.com[209.85.160.43] li305-246 postfix/smtpd[27091]: Anonymous TLS connection established from mail-pb0-f43.google.com[209.85.160.43]: TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits) li305-246 postfix/smtpd[27091]: warning: SASL authentication failure: Password verification failed li305-246 postfix/smtpd[27091]: warning: mail-pb0-f43.google.com[209.85.160.43]: SASL PLAIN authentication failed: authentication failure I've created accounts in userdb as per this tutorial. Does Postfix also use authuserdb? What debug information is needed to help diagnose my issue? main.cf: # TLS parameters smtpd_tls_cert_file = /etc/ssl/certs/smtpd.crt smtpd_tls_key_file = /etc/ssl/private/smtpd.key smtpd_use_tls=yes smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache # SMTP parameters smtpd_sasl_local_domain = smtpd_sasl_auth_enable = yes smtpd_sasl_security_options = noanonymous broken_sasl_auth_clients = yes smtpd_recipient_restrictions = permit_sasl_authenticated,permit_mynetworks,reject_unauth_destination smtp_tls_security_level = may smtpd_tls_security_level = may smtpd_tls_auth_only = no smtp_tls_note_starttls_offer = yes smtpd_tls_CAfile = /etc/ssl/certs/cacert.pem smtpd_tls_loglevel = 1 smtpd_tls_received_header = yes smtpd_tls_session_cache_timeout = 3600s tls_random_source = dev:/dev/urandom /etc/postfix/sasl/smtpd.conf pwcheck_method: saslauthd mech_list: plain login /etc/default/saslauthd START=yes PWDIR="/var/spool/postfix/var/run/saslauthd" PARAMS="-m ${PWDIR}" PIDFILE="${PWDIR}/saslauthd.pid" DESC="SASL Authentication Daemon" NAME="saslauthd" MECHANISMS="pam" MECH_OPTIONS="" THREADS=5 OPTIONS="-c -m /var/spool/postfix/var/run/saslauthd" /etc/courier/authdaemonrc authmodulelist="authuserdb" I've only modified one line in authdaemonrc and restarted the service as per this tutorial. I've added accounts to /etc/courier/userdb via userdb and userdbpw and run makeuserdb as per the tutorial. SOLVED Thanks to Jenny D for suggesting use of rimap to auth against localhost IMAP server (which reads userdb credentials). I updated /etc/default/saslauthd to start saslauthd correctly (this page was useful) MECHANISMS="rimap" MECH_OPTIONS="localhost" THREADS=0 OPTIONS="-c -m /var/spool/postfix/var/run/saslauthd -r" After doing this I got the following error in /var/log/auth.log: li305-246 saslauthd[28093]: auth_rimap: unexpected response to auth request: * BYE [ALERT] Fatal error: Account's mailbox directory is not owned by the correct uid or gid: li305-246 saslauthd[28093]: do_auth : auth failure: [user=fred] [service=smtp] [realm=] [mech=rimap] [reason=[ALERT] Unexpected response from remote authentication server] This blog post detailed a solution by setting IMAP_MAILBOX_SANITY_CHECK=0 in /etc/courier/imapd. Then restart your courier and saslauthd daemons for config changes to take effect. sudo /etc/init.d/courier-imap restart sudo /etc/init.d/courier-authdaemon restart sudo /etc/init.d/saslauthd restart Watch /var/log/auth.log while trying to send email. Hopefully you're good!

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  • Scientific Linux - mysql and apachefail to start on reboot

    - by Derek Deed
    Both mysqld and httpd fail to restart following a reboot of the server, although chkconfig --list shows both daemons set to on for run levels 2,3,4 & 5 All control is being exectuted via Webmin Reboot server – MySQl and Apache not running MySQL Database Server MySQL version 5.1.69 MySQL is not running on your system - database list could not be retrieved. Click this button to start the MySQL database server on your system with the command /etc/rc.d/init.d/mysqld start. This Webmin module cannot administer the database until it is started. Apache Webserver Apache version 2.2.15 Start Apache Search Docs.. Global configuration Existing virtual hosts Create virtual host Select all. | Invert selection. Default Server Defines the default settings for all other virtual servers, and processes any unhandled requests. Address Any Port Any Server Name Automatic Document Root /var/www/drupal Virtual Server Processes all requests on port 443 not handled by other virtual servers. Address Any Port 443 Server Name Automatic Document Root /var/www/drupal Select all. | Invert selection. chkconfig --list mysqld mysqld 0:off 1:off 2:on 3:on 4:on 5:on 6:off chkconfig --list httpd httpd 0:off 1:off 2:on 3:on 4:on 5:on 6:off Manually Restart Apache chkconfig --list httpd httpd 0:off 1:off 2:on 3:on 4:on 5:on 6:off Manually Restart MySQL chkconfig --list mysqld mysqld 0:off 1:off 2:on 3:on 4:on 5:on 6:off Everything now running okay; but no difference in the chkconfig outputs above. Set chkconfig --levels 235 httpd on /etc/init.d/httpd start The same for mysqld but no change in operation. Log files show that the shutdown has been completed successfully; but there is no indication of the service restarting until it is executed manually: 131112 13:59:15 InnoDB: Starting shutdown... 131112 13:59:16 InnoDB: Shutdown completed; log sequence number 0 881747021 131112 13:59:16 [Note] /usr/libexec/mysqld: Shutdown complete 131112 13:59:16 mysqld_safe mysqld from pid file /var/run/mysqld/mysqld.pid ended 131112 14:09:52 mysqld_safe Starting mysqld daemon with databases from /var/lib/mysql 131112 14:09:52 InnoDB: Initializing buffer pool, size = 8.0M 131112 14:09:52 InnoDB: Completed initialization of buffer pool [Tue Nov 12 13:59:13 2013] [notice] suEXEC mechanism enabled (wrapper: /usr/sbin/suexec) [Tue Nov 12 13:59:13 2013] [notice] Digest: generating secret for digest authentication ... [Tue Nov 12 13:59:13 2013] [notice] Digest: done [Tue Nov 12 13:59:14 2013] [notice] Apache/2.2.15 (Unix) DAV/2 PHP/5.3.3 mod_ssl/2.2.15 OpenSSL/1.0.0-fips configured -- resuming normal operations [Tue Nov 12 13:59:14 2013] [notice] caught SIGTERM, shutting down [Tue Nov 12 14:27:13 2013] [notice] suEXEC mechanism enabled (wrapper: /usr/sbin/suexec) [Tue Nov 12 14:27:13 2013] [notice] Digest: generating secret for digest authentication ... [Tue Nov 12 14:27:13 2013] [notice] Digest: done [Tue Nov 12 14:27:13 2013] [notice] Apache/2.2.15 (Unix) DAV/2 PHP/5.3.3 mod_ssl/2.2.15 OpenSSL/1.0.0-fips configured -- resuming normal operations Is anyone able to shed any light on this problem, Cheers, Derek.

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  • Scientific Linux - mysql and apache fail to start on reboot

    - by Derek Deed
    Both mysqld and httpd fail to restart following a reboot of the server, although chkconfig --list shows both daemons set to on for run levels 2,3,4 & 5 All control is being exectuted via Webmin Reboot server – MySQl and Apache not running MySQL Database Server MySQL version 5.1.69 MySQL is not running on your system - database list could not be retrieved. ________________________________________ Click this button to start the MySQL database server on your system with the command /etc/rc.d/init.d/mysqld start. This Webmin module cannot administer the database until it is started. Apache Webserver Apache version 2.2.15 Start Apache Search Docs.. Global configuration Existing virtual hosts Create virtual host Select all. | Invert selection. Default Server Defines the default settings for all other virtual servers, and processes any unhandled requests. Address Any Port Any Server Name Automatic Document Root /var/www/drupal Virtual Server Processes all requests on port 443 not handled by other virtual servers. Address Any Port 443 Server Name Automatic Document Root /var/www/drupal Select all. | Invert selection. chkconfig --list mysqld mysqld 0:off 1:off 2:on 3:on 4:on 5:on 6:off chkconfig --list httpd httpd 0:off 1:off 2:on 3:on 4:on 5:on 6:off Manually Restart Apache chkconfig --list httpd httpd 0:off 1:off 2:on 3:on 4:on 5:on 6:off Manually Restart MySQL chkconfig --list mysqld mysqld 0:off 1:off 2:on 3:on 4:on 5:on 6:off Everything now running okay; but no difference in the chkconfig outputs above. I tried: chkconfig --levels 235 httpd on /etc/init.d/httpd start and the same for mysqld but no change in operation. Log files show that the shutdown has been completed successfully; but there is no indication of the service restarting until it is executed manually: 131112 13:59:15 InnoDB: Starting shutdown... 131112 13:59:16 InnoDB: Shutdown completed; log sequence number 0 881747021 131112 13:59:16 [Note] /usr/libexec/mysqld: Shutdown complete 131112 13:59:16 mysqld_safe mysqld from pid file /var/run/mysqld/mysqld.pid ended 131112 14:09:52 mysqld_safe Starting mysqld daemon with databases from /var/lib/mysql 131112 14:09:52 InnoDB: Initializing buffer pool, size = 8.0M 131112 14:09:52 InnoDB: Completed initialization of buffer pool And the Apache logs: [Tue Nov 12 13:59:13 2013] [notice] suEXEC mechanism enabled (wrapper: /usr/sbin/suexec) [Tue Nov 12 13:59:13 2013] [notice] Digest: generating secret for digest authentication ... [Tue Nov 12 13:59:13 2013] [notice] Digest: done [Tue Nov 12 13:59:14 2013] [notice] Apache/2.2.15 (Unix) DAV/2 PHP/5.3.3 mod_ssl/2.2.15 OpenSSL/1.0.0-fips configured -- resuming normal operations [Tue Nov 12 13:59:14 2013] [notice] caught SIGTERM, shutting down [Tue Nov 12 14:27:13 2013] [notice] suEXEC mechanism enabled (wrapper: /usr/sbin/suexec) [Tue Nov 12 14:27:13 2013] [notice] Digest: generating secret for digest authentication ... [Tue Nov 12 14:27:13 2013] [notice] Digest: done [Tue Nov 12 14:27:13 2013] [notice] Apache/2.2.15 (Unix) DAV/2 PHP/5.3.3 mod_ssl/2.2.15 OpenSSL/1.0.0-fips configured -- resuming normal operations Is anyone able to shed any light on this problem?

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  • What is the current state of Ubuntu's transition from init scripts to Upstart? [migrated]

    - by Adam Eberlin
    What is the current state of Ubuntu's transition from init.d scripts to upstart? I was curious, so I compared the contents of /etc/init.d/ to /etc/init/ on one of our development machines, which is running Ubuntu 12.04 LTS Server. # /etc/init.d/ # /etc/init/ acpid acpid.conf apache2 --------------------------- apparmor --------------------------- apport apport.conf atd atd.conf bind9 --------------------------- bootlogd --------------------------- cgroup-lite cgroup-lite.conf --------------------------- console.conf console-setup console-setup.conf --------------------------- container-detect.conf --------------------------- control-alt-delete.conf cron cron.conf dbus dbus.conf dmesg dmesg.conf dns-clean --------------------------- friendly-recovery --------------------------- --------------------------- failsafe.conf --------------------------- flush-early-job-log.conf --------------------------- friendly-recovery.conf grub-common --------------------------- halt --------------------------- hostname hostname.conf hwclock hwclock.conf hwclock-save hwclock-save.conf irqbalance irqbalance.conf killprocs --------------------------- lxc lxc.conf lxc-net lxc-net.conf module-init-tools module-init-tools.conf --------------------------- mountall.conf --------------------------- mountall-net.conf --------------------------- mountall-reboot.conf --------------------------- mountall-shell.conf --------------------------- mounted-debugfs.conf --------------------------- mounted-dev.conf --------------------------- mounted-proc.conf --------------------------- mounted-run.conf --------------------------- mounted-tmp.conf --------------------------- mounted-var.conf networking networking.conf network-interface network-interface.conf network-interface-container network-interface-container.conf network-interface-security network-interface-security.conf newrelic-sysmond --------------------------- ondemand --------------------------- plymouth plymouth.conf plymouth-log plymouth-log.conf plymouth-splash plymouth-splash.conf plymouth-stop plymouth-stop.conf plymouth-upstart-bridge plymouth-upstart-bridge.conf postgresql --------------------------- pppd-dns --------------------------- procps procps.conf rc rc.conf rc.local --------------------------- rcS rcS.conf --------------------------- rc-sysinit.conf reboot --------------------------- resolvconf resolvconf.conf rsync --------------------------- rsyslog rsyslog.conf screen-cleanup screen-cleanup.conf sendsigs --------------------------- setvtrgb setvtrgb.conf --------------------------- shutdown.conf single --------------------------- skeleton --------------------------- ssh ssh.conf stop-bootlogd --------------------------- stop-bootlogd-single --------------------------- sudo --------------------------- --------------------------- tty1.conf --------------------------- tty2.conf --------------------------- tty3.conf --------------------------- tty4.conf --------------------------- tty5.conf --------------------------- tty6.conf udev udev.conf udev-fallback-graphics udev-fallback-graphics.conf udev-finish udev-finish.conf udevmonitor udevmonitor.conf udevtrigger udevtrigger.conf ufw ufw.conf umountfs --------------------------- umountnfs.sh --------------------------- umountroot --------------------------- --------------------------- upstart-socket-bridge.conf --------------------------- upstart-udev-bridge.conf urandom --------------------------- --------------------------- ureadahead.conf --------------------------- ureadahead-other.conf --------------------------- wait-for-state.conf whoopsie whoopsie.conf To be honest, I'm not entirely sure if I'm interpreting the division of responsibilities properly, as I didn't expect to see any overlap (of what framework handles which services). So I was quite surprised to learn that there was a significant amount of overlap in service references, in addition to being unable to discern which of the two was intended to be the primary service framework. Why does there seem to be a fair amount of redundancy in individual service handling between init.d and upstart? Is something else at play here that I'm missing? What is preventing upstart from completely taking over for init.d? Is there some functionality that certain daemons require which upstart does not yet have, which are preventing some services from converting? Or is it something else entirely?

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  • MegaCli newly created disk doesn't appear under /dev/sdX

    - by Henry-Nicolas Tourneur
    After having successfully added 2 new disks in a new RAID virtual drive (background initialization done), I would have exepected it to appear under /dev/sdh but it's not there (so, unusable). The system is running a CentOS 5.2 64 bits, HAL and udev daemons are running, not records of any sdh apparition under the messsage log file or in dmesg, only MegaCli do see that virtual drive. Any idea ? Some data: [root@server ~]# ./MegaCli -LDInfo -LALL -a0 Adapter 0 -- Virtual Drive Information: Virtual Disk: 0 (target id: 0) Name: RAID Level: Primary-1, Secondary-0, RAID Level Qualifier-0 Size:139392MB State: Optimal Stripe Size: 64kB Number Of Drives:2 Span Depth:1 Default Cache Policy: WriteBack, ReadAheadNone, Direct, No Write Cache if Bad BBU Current Cache Policy: WriteBack, ReadAheadNone, Direct, No Write Cache if Bad BBU Access Policy: Read/Write Disk Cache Policy: Disk's Default Virtual Disk: 1 (target id: 1) Name: RAID Level: Primary-1, Secondary-0, RAID Level Qualifier-0 Size:285568MB State: Optimal Stripe Size: 64kB Number Of Drives:2 Span Depth:1 Default Cache Policy: WriteBack, ReadAheadNone, Direct, No Write Cache if Bad BBU Current Cache Policy: WriteBack, ReadAheadNone, Direct, No Write Cache if Bad BBU Access Policy: Read/Write Disk Cache Policy: Disk's Default [root@server ~]# ls -l /dev/disk/by-id/scsi-360* lrwxrwxrwx 1 root root 9 Nov 17 2010 /dev/disk/by-id/scsi-36001ec90f82fe100108ca0a704098d09 -> ../../sda lrwxrwxrwx 1 root root 10 Nov 17 2010 /dev/disk/by-id/scsi-36001ec90f82fe100108ca0a704098d09-part1 -> ../../sda1 lrwxrwxrwx 1 root root 10 Nov 17 2010 /dev/disk/by-id/scsi-36001ec90f82fe100108ca0a704098d09-part2 -> ../../sda2 lrwxrwxrwx 1 root root 9 Nov 17 2010 /dev/disk/by-id/scsi-36090a028e0fe07e78f94940c0000a0ee -> ../../sdf lrwxrwxrwx 1 root root 10 Nov 17 2010 /dev/disk/by-id/scsi-36090a028e0fe07e78f94940c0000a0ee-part1 -> ../../sdf1 lrwxrwxrwx 1 root root 9 Nov 17 2010 /dev/disk/by-id/scsi-36090a028e0fe972a3f91240a0000005f -> ../../sdb lrwxrwxrwx 1 root root 10 Nov 17 2010 /dev/disk/by-id/scsi-36090a028e0fe972a3f91240a0000005f-part1 -> ../../sdb1 lrwxrwxrwx 1 root root 9 Nov 17 2010 /dev/disk/by-id/scsi-36090a028e0fea7e18f94640c000020ec -> ../../sde lrwxrwxrwx 1 root root 10 Nov 17 2010 /dev/disk/by-id/scsi-36090a028e0fea7e18f94640c000020ec-part1 -> ../../sde1 lrwxrwxrwx 1 root root 9 Nov 17 2010 /dev/disk/by-id/scsi-36090a028e0feb7da8f94340c0000203d -> ../../sdd lrwxrwxrwx 1 root root 10 Nov 17 2010 /dev/disk/by-id/scsi-36090a028e0feb7da8f94340c0000203d-part1 -> ../../sdd1 lrwxrwxrwx 1 root root 9 Nov 17 2010 /dev/disk/by-id/scsi-36090a028e0fed7d78f94040c000080b7 -> ../../sdc lrwxrwxrwx 1 root root 10 Nov 17 2010 /dev/disk/by-id/scsi-36090a028e0fed7d78f94040c000080b7-part1 -> ../../sdc1 lrwxrwxrwx 1 root root 9 Nov 17 2010 /dev/disk/by-id/scsi-36090a05830145e58e0b9c479000010a1 -> ../../sdg lrwxrwxrwx 1 root root 10 Nov 17 2010 /dev/disk/by-id/scsi-36090a05830145e58e0b9c479000010a1-part1 -> ../../sdg1

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  • How to get the best LINPACK result and conquer the Top500?

    - by knweiss
    Given a large Linux HPC cluster with hundreds/thousands of nodes. What are your best practices to get the best possible LINPACK benchmark (HPL) result to submit for the Top500 supercomputer list? To give you an idea what kind of answers I would appreciate here are some sub-questions (with links): How to you tune the parameters (N, NB, P, Q, memory-alignment, etc) for the HPL.dat file (without spending too much time trying each possible permutation - esp with large problem sizes N)? Are there any Top500 submission rules to be aware of? What is allowed, what isn't? Which MPI product, which version? Does it make a difference? Any special host order in your MPI machine file? Do you use CPU pinning? How to you configure your interconnect? Which interconnect? Which BLAS package do you use for which CPU model? (Intel MKL, AMD ACML, GotoBLAS2, etc.) How do you prepare for the big run (on all nodes)? Start with small runs on a subset of nodes and then scale up? Is it really necessary to run LINPACK with a big run on all of the nodes (or is extrapolation allowed)? How do you optimize for the latest Intel/AMD CPUs? Hyperthreading? NUMA? Is it worth it to recompile the software stack or do you use precompiled binaries? Which settings? Which compiler optimizations, which compiler? (What about profile-based compilation?) How to get the best result given only a limited amount of time to do the benchmark run? (You can block a huge cluster forever) How do you prepare the individual nodes (stopping system daemons, freeing memory, etc)? How do you deal with hardware faults (ruining a huge run)? Are there any must-read documents or websites about this topic? E.g. I would love to hear about some background stories of some of the current Top500 systems and how they did their LINPACK benchmark. I deliberately don't want to mention concrete hardware details or discuss hardware recommendations because I don't want to limit the answers. However, feel free to mention hints e.g. for specific CPU models.

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