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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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  • R2 live migration between Opteron 8354 and 2435

    - by Safin09
    As per title, will the processor compatibility option allow a live migrate between an AMD Opeteron 2435 (dual proc, hex core) and an AMD Opteron 8354 (quad proc, quad core)? We are out of capacity and wish to use a newer dual socket server rather than an older (yet much more expensive) quad socket server in our cluster.

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  • Some emails are being delivered, some returned

    - by Tom Broucke
    I have my own VPS where a site is running (control panel: directadmin). When I send mails, some are being delivered (hotmail, gmail, [email protected] ,...), others are not ([email protected]), others are delivered after being greylisted ([email protected]). /var/log/exim/mainlog What could be the cause of this? Is the problem Sender-Side or Receiver-Side? case 1: [email protected] (delivered) 2012-06-20 15:02:03 1ShKXr-0005Sc-7g <= [email protected] U=apache P=local S=1319 T="Password reset" from <[email protected]> for [email protected] 2012-06-20 15:02:03 1ShKXr-0005Sc-7g gmail-smtp-in-v4v6.l.google.com [2a00:1450:8005::1b] Network is unreachable 2012-06-20 15:02:03 1ShKXr-0005Sc-7g => [email protected] F=<[email protected]> R=lookuphost T=remote_smtp S=1355 H=gmail-smtp-in-v4v6.l.google.com [173.194.67.27] X=TLSv1:RC4-SHA:128 C="250 2.0.0 OK 1340196103 cp4si34336466wib.14" 2012-06-20 15:02:03 1ShKXr-0005Sc-7g Completed case 2: [email protected] (not being delivered) 2012-06-21 09:57:14 1ShcGQ-0007No-5H <= [email protected] H=localhost ([91.230.245.141]) [127.0.0.1] P=esmtpa A=login:[email protected] S=740 [email protected] T="hey" from <[email protected]> for [email protected] 2012-06-21 09:57:14 1ShcGQ-0007No-5H ** [email protected] F=<[email protected]> R=virtual_aliases: 2012-06-21 09:57:14 1ShcGQ-0007Nt-7Z <= <> R=1ShcGQ-0007No-5H U=mail P=local S=1546 T="Mail delivery failed: returning message to sender" from <> for [email protected] 2012-06-21 09:57:14 1ShcGQ-0007No-5H Completed 2012-06-21 09:57:14 1ShcGQ-0007Nt-7Z => info <[email protected]> F=<> R=virtual_user T=virtual_localdelivery S=1643 2012-06-21 09:57:14 1ShcGQ-0007Nt-7Z Completed case 3: [email protected] (greylisted) 2012-06-21 15:29:02 1ShhRW-000862-BV <= [email protected] H=localhost ([91.230.245.141]) [127.0.0.1] P=esmtpa A=login:[email protected] S=782 [email protected] T="testmail squirrel" from <[email protected]> for [email protected] 2012-06-21 15:29:02 1ShhRW-000862-BV SMTP error from remote mail server after RCPT TO:<[email protected]>: host mx-cluster-b1.one.com [195.47.247.194]: 450 4.7.1 <[email protected]>: Recipient address rejected: Greylisted for 5 minutes 2012-06-21 15:29:02 1ShhRW-000862-BV == [email protected] R=lookuphost T=remote_smtp defer (-44): SMTP error from remote mail server after RCPT TO:<[email protected]>: host mx-cluster-b2.one.com [195.47.247.195]: 450 4.7.1 <[email protected]>: Recipient address rejected: Greylisted for 5 minutes Notice that the "from" in case1 differs in case2: [email protected] or [email protected]. Thanks for your time!

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  • Network and Server Management Tools

    - by jessieE
    We are building a farm of test servers. Currently we have 8 servers. We are planning to use the servers to test the following Mysql Cluster Xen or KVM virtualization Heartbeat/Pacemaker/DRDB What tools do experienced sysads use for: Initial installation of operating system( installing centos 5 or ubuntu server manually 8 times seems like a tedious task that just begs for automation) Centralized Configuration Management and Software Updates for Host and possibly Guest(virtualized) servers Hardware, Services and Network Monitoring

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  • Advice on where to install Redis

    - by redsquare
    I have just introduced Redis into our application and I am not sure where best to install in production. I read that the Windows option is not production quality so i need to install on Linux. I currently have 5 redhat boxes and cannot get any more provisioned at this current time. These consist of Active/Passive HaProxy load balancer and a cluster of three RabbitMQ boxes. Where would you install an Active/Passive redis instances?

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  • Secure, efficient, version-preserving, filename-hiding backup implemented in this way?

    - by barrycarter
    I tried writing a "perfect" backup program (below), but ran into problems (also below). Is there an efficient/working version of this?: Assumptions: you're backing up from 'local', which you own and has limited disk space to 'remote', which has infinite disk space and belongs to someone else, so you need encryption. Network bandwidth is finite. 'local' keeps a db of backed-up files w/ this data for each file: filename, including full path file's last modified time (mtime) sha1sum of file's unencrypted contents sha1sum of file's encrypted contents Given a list of files to backup (some perhaps already backed up), the program runs 'find' and gets the full path/mtime for each file (this is fairly efficient; conversely, computing the sha1sum of each file would NOT be efficient) The program discards files whose filename and mtime are in 'local' db. The program now computes the sha1sum of the (unencrypted contents of each remaining file. If the sha1sum matches one in 'local' db, we create a special entry in 'local' db that points this file/mtime to the file/mtime of the existing entry. Effectively, we're saying "we have a backup of this file's contents, but under another filename, so no need to back it up again". For each remaining file, we encrypt the file, take the sha1sum of the encrypted file's contents, rsync the file to its sha1sum. Example: if the file's encrypted sha1sum was da39a3ee5e6b4b0d3255bfef95601890afd80709, we'd rsync it to /some/path/da/39/a3/da39a3ee5e6b4b0d3255bfef95601890afd80709 on 'remote'. Once the step above succeeds, we add the file to the 'local' db. Note that we efficiently avoid computing sha1sums and encrypting unless absolutely necessary. Note: I don't specify encryption method: this would be user's choice. The problems: We must encrypt and backup 'local' db regularly. However, 'local' db grows quickly and rsync'ing encrypted files is inefficient, since a small change in 'local' db means a big change in the encrypted version of 'local' db. We create a file on 'remote' for each file on 'local', which is ugly and excessive. We query 'local' db frequently. Even w/ indexes, these queries are slow, since we're often making one query for each file. Would be nice to speed this up by batching queries or something. Probably other problems that I've now forgotten.

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  • High availability for databases (DRBD + GFS)?

    - by EvanAlm
    Does it work to have like an MySQL (or any other relational database) on the GFS (with DRBD) and have multiple nodes reading and writing to it? Is that the "best" way of providing a HA database/application setup if so? Is RHEL (cluster suite) a good way to set up this? (or centos)

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  • Windows HPC Server 08 suitability for Matlabs

    - by blade
    I want to setup another Hyper-V VM for installing Matlabs/doing some compute-intensive programming using C. I keep thinking that Windows Server HPC 2008 is designed for this sort of work. Would I be on the right track to setup a single VM with this OS and install this software? Or is HPC more for grid/distributed computing? Thanks

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  • Unable to uninstall SQL 2008 Instance(s)

    - by ichoudhury
    Windows 2008 R2 High Availability Cluster and we were just going through the first phase of configuration. Somebody accidentally loaded the instance incorrectly, so I was hopping to uninstall and reinstall. But when I approach the uninstall process, it fails with the following msg: Object reference not set to an instance of an object SQL instance not yet clustered (FYI) Any idea?

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  • Does changing the default HDFS replication factor from 3 affect mapper performance?

    - by liamf
    Have a HDFS/Hadoop cluster setup and am looking into tuning. I wonder if changing the default HDFS replication factor (default:3) to something bigger will improve mapper performance, at the obvious expense of increasing disk storage used? My reasoning being that if the data is already replicated to more nodes, mapper jobs can be run on more nodes in parallel without any data streaming/copying? Anyone got any opinions?

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  • Switch User in RedHat like XP

    - by rd42
    In our cluster, RedHat4 & 5 machines, if someone locks the computer and walks away no body can use it. Is there a feature in RedHat5, Gnome, KDE etc that would allow for the option of switching users at the lock screen, so more than one person can be logged in? Thanks, rd42

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  • Group your tabs feature Firefox: Automatically sort by domain?

    - by Dan
    I'm using Firefox 8.0 and am enjoying the Group your tabs feature: But I'm not always good at keeping it organized. I'm trying to find a way to automatically put certain domains in certain groups. Probably through a plug-in? All the tab related plug-ins just help cluster your tabs together and don't actually work with the "Group your tabs" feature (which is why I posted the picture, to avoid ambiguity, since grouping tabs can refer to a lot of things).

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  • High CPU usage - symptoms moving from server to server after bouncing

    - by grt3kl
    First off, I apologize if I didn't include enough information to properly troubleshoot this issue. This sort of thing isn't my specialty, so it is a learning process. If there's something I need to provide, please let me know and I'll be happy to do what I can. The images associated with my question are at the bottom of this post. We are dealing with a clustered environment of four WebLogic 9.2 Java application servers. The cluster utilizes a round-robin load algorithm. Other details include: Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0_12-b04) BEA JRockit(R) (build R27.4.0-90_CR352234-91983-1.5.0_12-20071115-1605-linux-x86_64, compiled mode) Basically, I started looking at the servers' performance because our customers are seeing lots of lag at various times of the day. Our servers should easily handle the loads they are given, so it's not clear what's going on. Using HP Performance Manager, I generated some graphs that indicate that the CPU usage is completely out of whack. It seems that, at any given point, one or more of the servers has a CPU utilization of over 50%. I know this isn't particularly high, but I would say it is a red flag based on the CPU utilization of the other servers in the WebLogic cluster. Interesting things to note: The high CPU utilization was occurring only on server02 for several weeks. The server crashed (extremely rare; we are not sure if it's related to this) and upon starting it back up, the CPU utilization was normal on all 4 servers. We restarted all 4 managed servers and the application server (on server01) yesterday, on 2/28. As you can see, server03 and server04 picked up the behavior that was seen on server02 before. The CPU utilization is a Java process owned by the application user (appown). The number of transactions is consistent across all servers. It doesn't seem like any one server is actually handling more than another. If anyone has any ideas or can at least point me in the right direction, that would be great. Again, please let me know if there is any additional information I should post. Thanks!

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  • OS X - forwarding external port to local loopback address

    - by Rory Fitzpatrick
    I have an HTTP service bound to port 8000 that I want to access from another computing on the network, but I can't seem to connect using the external IP address of the machine (e.g. 192.168.0.105). I've checked the OS X firewall isn't running, so I'm assuming the issue is the service is only bound to the IP address 127.0.0.1, and not the external IP address. What would be the easiest way to temporarily forward external connections on port 8000 to 127.0.0.1:8000?

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  • Multicast Prblem in Linux Red Hat server

    - by Uma Kant Verma
    I am facing a very strange behavior on my server. I am using a linux cluster.On fail over server my broadcast application halts after 5 minutes.But it is working fine on Primary server. My application process listening on port and send broadcast.It is working 5 mins after that it wait on socket for further packets but it didn't receive anything. Same process is working fine at Primary server. Plz help me.

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  • Benefits to private networks between virtual machines on an ESXi host?

    - by arex1337
    I'm planning this development environment with a few database servers, and originally thought I would have a few private networks. I then thought it might be unnecessary as the ESXi cluster already provides redundancy with 4 NICs (in my case) and should manage the network traffic pretty intelligently, right? Two private networks Zero private networks What are the advantages/disadvantages between the two shown configurations - on an ESXi 4.1 host?

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  • problem installing netbeans on freeBSD

    - by solomon
    hi guys, I want to install netbeans on my freeBSD7.2 machine.I followed the instructions listed in http://typo.submonkey.net/articles/2007/7/13/netbeans-on-freebsd But, when i try the third step, which is running the netbeans using "./netbeans/bin/netbeans" i found the following error "etc/netbeans.cluster" file cann't be found. What do u think could be the reason. I can't figure it out, plz help me. Thanx in advance

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  • Need suggestions for a Sigle Board Linux Computer?

    - by Joernsn
    I need suggestions for a single board computer, with these requirements: Runs linux Wifi (I/O module?) Does not need much computing power. I'm using it for applications like twittering when the coffee at the office is ready etc. I'd like it to run linux, for easy scripting and a full network stack. (preferably pre-installed)

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  • PowerISO for Mac can't convert .img

    - by None
    I have a bootable .img file that I want to convert to a bootable .iso file. I downloaded poweriso for Mac and used this command: poweriso convert MyOS.img -o MyOS.iso -ot iso which returned this output: PowerISO Copyright(C) 2004-2008 PowerISO Computing, Inc Type poweriso -? for help MyOS.img: The file format is invalid or unsupported. I thought PowerISO could convert .img to .iso. Was I incorrect, or did I use the wrong commands or something like that?

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