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  • Websphere SSL handshake with active directory cluster

    - by ring bearer
    We have a WebSphere based application that uses Active Directory(AD) based security configurations. Under WebSphere "Global security" we have configured the active directory server and connection parameters. Active directory server is actually a cluster of four servers, say, serverdc01, serverdc02,serverdc03 and serverdc04. Each of these servers have their own root certificate with CN=serverdc01, CN=serverdc02 ..so on. So to set up SSL communication, I need to retrieve certificate of active directory and save it in WebSphere's trust store. When I retrieve certificate by putting AD server name, port and retrieve certificate I randomly get certificate of one of the serverdc01,serverdc02 ... Then I save that certificate to trust store. Question is : Do I have to save certificate from each of the serverdc01,serverdc02 ...in cluster to WebSphere's trust store? What are general strategies so that each server in the cluster does not require its own root certificate?

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  • Best practice for administering a (hadoop) cluster

    - by Alex
    Dear all, I've recently been playing with Hadoop. I have a six node cluster up and running - with HDFS, and having run a number of MapRed jobs. So far, so good. However I'm now looking to do this more systematically and with a larger number of nodes. Our base system is Ubuntu and the current setup has been administered using apt (to install the correct java runtime) and ssh/scp (to propagate out the various conf files). This is clearly not scalable over time. Does anyone have any experience of good systems for administering (possibly slightly heterogenous: different disk sizes, different numbers of cpus on each node) hadoop clusters automagically? I would consider diskless boot - but imagine that with a large cluster, getting the cluster up and running might be bottle-necked on the machine serving the OS. Or some form of distributed debian apt to keep the machines native environment synchronised? And how do people successfully manage the conf files over a number of (potentially heterogenous) machines? Thanks very much in advance, Alex

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  • Write hash password to LDAP when creating a new user

    - by alibaba
    I am working on a project with a central user database system. One of the requirements of the system is that there should be only one set of users for all the application. FreeRADIUS and Samba are two my applications that both use LDAP as their backend. Since users must be the same for the entire system that contains many other applications, I have to read the list of users from the central database and recreate them in the LDAP directories for Samba and FreeRADIUS. The problem is that users are sent to me from another entity and I can save them in the database with their hash passwords. I don't have access to their cleartext passwords. I am wondering if I could enter directly a hash password for a new user in LDAP with my preferred hash mechanism. If not, can any one tell me what strategy I have to use? I am running my server on UBUNTU 12.04 and all other applications are the latest versions. My database system is PostgreSQL 9.2. Thank you

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  • Python MD5 Hash Faster Calculation

    - by balgan
    Hi everyone. I will try my best to explain my problem and my line of thought on how I think I can solve it. I use this code for root, dirs, files in os.walk(downloaddir): for infile in files: f = open(os.path.join(root,infile),'rb') filehash = hashlib.md5() while True: data = f.read(10240) if len(data) == 0: break filehash.update(data) print "FILENAME: " , infile print "FILE HASH: " , filehash.hexdigest() and using start = time.time() elapsed = time.time() - start I measure how long it takes to calculate an hash. Pointing my code to a file with 653megs this is the result: root@Mars:/home/tiago# python algorithm-timer.py FILENAME: freebsd.iso FILE HASH: ace0afedfa7c6e0ad12c77b6652b02ab 12.624 root@Mars:/home/tiago# python algorithm-timer.py FILENAME: freebsd.iso FILE HASH: ace0afedfa7c6e0ad12c77b6652b02ab 12.373 root@Mars:/home/tiago# python algorithm-timer.py FILENAME: freebsd.iso FILE HASH: ace0afedfa7c6e0ad12c77b6652b02ab 12.540 Ok now 12 seconds +- on a 653mb file, my problem is I intend to use this code on a program that will run through multiple files, some of them might be 4/5/6Gb and it will take wayy longer to calculate. What am wondering is if there is a faster way for me to calculate the hash of the file? Maybe by doing some multithreading? I used a another script to check the use of the CPU second by second and I see that my code is only using 1 out of my 2 CPUs and only at 25% max, any way I can change this? Thank you all in advance for the given help.

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  • I'm trying to understand hash tables - can someone explain it to me - clearly?

    - by Stevo
    I want to understand the correct use and implementation of hash tables in php (sorry). I read somewhere that an in-experienced programmer created a hash table and then iterated through it. Now, I understand why that is wrong but I haven't quite got the full knowledge to know if my understanding is correct (if you know what I mean). So could someone explain to me how to implement a hash table in php (presumably an associative array) and perhaps more importantly, how to access the values 'with a hash' and what that actually means?

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  • VMware vSphere cluster design for site redundancy

    - by Stefan Radovanovici
    I have a question about the best design for site redudancy when using vSphere clusters. A bit of background info about our situation first though. We are a medium-sized company with two main offices, located in different countries. Our networks are linked by a Layer2 150Mbps leased line which is currently underused. We have a variety of services running for internal use within the company, some on physycal servers and some on existing vSphere clusters. In our department we also run several services (almost all running under various forms of Linux) like NTP, Syslog, jump servers, monitoring servers and so on. We have now the requirement that those servers need to be redundant within each location (which they are not at the moment) and also site redudant (which they are to some extent, the servers are duplicated in the 2nd location with configurations kept in sync via various methods at the application layer). There is no SAN available for us, at least not something that we can use at the moment. Cost is also an issue. While we do have some budget available for this, we can't afford to buy SANs for both locations for example. I looked at the VSA feature and it seems that this could be something for us but I am unsure how to solve the site-redudancy requirement. At the moment for testing purposes I am setting up in a lab a vSphere 5 with VSA on two ESXi hosts. I am currently using the Essentials Plus kit with VSA license, which allows me to build a VSA cluster on up to 3 hosts, together with a vCenter license to manage them. The hosts each have two dual-port network cards and two 600GB drives, running in Raid1. Hardware-wise this will be enough for us to run the all the services we need as VMs and will provide redundandcy within the site. At the moment I see only two option to have site redundancy: build an identical VSA cluter in the second location and keep the various services sync'ed at application layer (database sync, rsync and so on). simply move one of the hosts from the existing cluster to the second location, basically having the VSA cluster span the 150Mbps link between the sites. I would very much prefer the second option but I am unsure how well it'll work, if it can work at all. Technically it should, we can span the needed VLANs across the leased line and have them available in the second location. The advantage would be that we don't need to worry at all about sync'ing databases and the like. But I have the feeling that the bandwidth will not be enough, I have no way of knowing how much traffic will the VSA cluster generate between the hosts. I realize that this will most likely depend on the individual usage of the VMs but still, I have no idea how VSA replicates data between the ESXi hosts. Are these my only options or can my goals be achieved in some other way ? Is there perhaps a way to have some sort of "cold stand by" cluster in the second location where the VMs would be sync'ed once per night from the main location ? The idea is that in case the first site becomes unavailable, we would be able to bring all those VMs online there. We would be ok with the data being 1 day old. Any answers are appreciated. Best regards, Stefan

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  • Custom .NET apps and clustering

    - by Ahmed ilyas
    So for a clustered environment - how would this work with your apps? what about your own custom .NET apps? Would there be a special way to develop them? I know that you can say create a simple Hello world app, and cluster that but they wouldnt be something you could see interms of the UI or anything, so they would effectively need to be developed as a Windows Service perhaps or even as a standard Console app which runs and not wait for user input but you wouldnt see any output from it (unless you redirect output to somewhere else) What im getting at here is... for those who have experience or developed a cluster application in .NET, how did you do it and what are the things to be aware of? For example we have the cloud service - fundamentally its built on clustering - if there is an outage, another node takes place and service is resumed as normal but we dont really see much of that downtime.

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  • The algorithm used to generate recommendations in Google News?

    - by Siddhant
    Hi everyone. I'm study recommendation engines, and I went through the paper that defines how Google News generates recommendations to users for news items which might be of their interest, based on collaborative filtering. One interesting technique that they mention is Minhashing. I went through what it does, but I'm pretty sure that what I have is a fuzzy idea and there is a strong chance that I'm wrong. The following is what I could make out of it :- Collect a set of all news items. Define a hash function for a user. This hash function returns the index of the first item from the news items which this user viewed, in the list of all news items. Collect, say "n" number of such values, and represent a user with this list of values. Based on the similarity count between these lists, we can calculate the similarity between users as the number of common items. This reduces the number of comparisons a lot. Based on these similarity measures, group users into different clusters. This is just what I think it might be. In Step 2, instead of defining a constant hash function, it might be possible that we vary the hash function in a way that it returns the index of a different element. So one hash function could return the index of the first element from the user's list, another hash function could return the index of the second element from the user's list, and so on. So the nature of the hash function satisfying the minwise independent permutations condition, this does sound like a possible approach. Could anyone please confirm if what I think is correct? Or the minhashing portion of Google News Recommendations, functions in some other way? I'm new to internal implementations of recommendations. Any help is appreciated a lot. Thanks!

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  • Win'08 - Extend volume size on SAN attached storage in a failover cluster

    - by user53207
    Running Win 2008, I'd like to extend the volume of a SAN attached drive that is part of a failover cluster. The SAN team has allocated additional drive space which is being seen by Windows Storage Manager. However, the option to "Extend Volume" is disabled, so is the ability to turn it into a dynamic disk. Is the ability to extend volumes when part of a failover cluster disabled or not available when it's part of SAN attached storage?

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  • Tool to compute SHA256 Tree Hash

    - by Benjamin
    I've started using AWS Glacier, and noticed that it hashes the files using an algorithm called SHA-256 Tree Hash. To my surprise, this algorithm is different from SHA-256, so I can't use the tools I'm used to, to compare hashes and verify file integrity. Do you know a Windows tool, if possible integrated in the context menu, to compute the SHA-256 Tree Hash of a file? I'd also accept a Linux command-line tool, as a second choice :-)

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  • where to put core services in two-node cluster

    - by Veniamin
    I'm currently configuring two-node HA cluster based on CentOS with DRBD. Most services are packed in virtual machines with migration available. I have not made decision where to put some core services as: dhcp, ldap, dns - which are critical for all network infrastructure. There are two possibilities: Configure them as redundant HA services on cluster hosts. Pack them all into dedicated virtual machine. What is the best practice?

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  • Hyper-V SERVER R2 Cluster

    - by ToreTrygg
    I keep hearing and reading that Hyper-V Server 2008 R2 can be clustered, but I can't find out how to set this up. I can find how to cluster Windows Server 2008 R2 with Hyper-V. I understand how to do this, bBut "How do you set up Hyper-V SERVER 2008 R2 in a cluster"? Thanks.

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  • Test Environment for Microsoft SQL Cluster

    - by user195643
    I have a the following test environment: 1 - Windows 2008 (DC Edition) Role - Active Directory 2 - Windows 2008 (Enterprise Servers) I would like to create a MSSQL Cluster in this test environment. I am using a desktop PC and I would like to know how I can configure second network card in order to configure the MSSQL Cluster? and how I can use a shared storage without using any external drives?

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  • MySQL Hashing Function Implementation

    - by Jonas Stevens
    I know that php has md5(), sha1(), and the hash() functions, but I want to create a hash using the MySQL PASSWORD() function. So far, the only way I can think of is to just query the server, but I want a function (preferably in php or Perl) that will do the same thing without querying MySQL at all. For example: MySQL hash - 464bb2cb3cf18b66 MySQL5 hash - *01D01F5CA7CA8BA771E03F4AC55EC73C11EFA229 Thanks!

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  • hashing password giving different results

    - by geoff
    I am taking over a system that a previous developer wrote. The system has an administrator approve a user account and when they do that the system uses the following method to hash a password and save it to the database. It sends the unhashed password to the user. When the user logs in the system uses the exact same method to hash what the user enters and compares it to the database value. We've run into a couple of times when the database entry doesn't match the user's entry whey they should. So it appears that the method isn't always hashing the value the same. Does anyone know if this method of hashing isn't reliable and how to make it reliable? Thanks. private string HashPassword(string password) { string hashedPassword = string.Empty; // Convert plain text into a byte array. byte[] plainTextBytes = Encoding.UTF8.GetBytes(password); // Allocate array, which will hold plain text and salt. byte[] plainTextWithSaltBytes = new byte[plainTextBytes.Length + SALT.Length]; // Copy plain text bytes into resulting array. for(int i = 0; i < plainTextBytes.Length; i++) plainTextWithSaltBytes[i] = plainTextBytes[i]; // Append salt bytes to the resulting array. for(int i = 0; i < SALT.Length; i++) plainTextWithSaltBytes[plainTextBytes.Length + i] = SALT[i]; // Because we support multiple hashing algorithms, we must define // hash object as a common (abstract) base class. We will specify the // actual hashing algorithm class later during object creation. HashAlgorithm hash = new SHA256Managed(); // Compute hash value of our plain text with appended salt. byte[] hashBytes = hash.ComputeHash(plainTextWithSaltBytes); // Create array which will hold hash and original salt bytes. byte[] hashWithSaltBytes = new byte[hashBytes.Length + SALT.Length]; // Copy hash bytes into resulting array. for(int i = 0; i < hashBytes.Length; i++) hashWithSaltBytes[i] = hashBytes[i]; // Append salt bytes to the result. for(int i = 0; i < SALT.Length; i++) hashWithSaltBytes[hashBytes.Length + i] = SALT[i]; // Convert result into a base64-encoded string. hashedPassword = Convert.ToBase64String(hashWithSaltBytes); return hashedPassword; }

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  • Are fragments of hashes collision-resistent?

    - by Mark
    Let me see if someone would mind clearing up this elementary point about md5 and hashing. If you only use the first 4 bytes of an md5 hash, would that mean theoretically only 1 in 255^4 chance of collision. iow is that the intention with it (and other hash algorithms) - that you only have to use a small portion of the returned hash (say the hash is of a file of some size).

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  • Optimizing hash lookup & memory performance in Go

    - by Moishe
    As an exercise, I'm implementing HashLife in Go. In brief, HashLife works by memoizing nodes in a quadtree so that once a given node's value in the future has been calculated, it can just be looked up instead of being re-calculated. So eg. if you have a node at the 8x8 level, you remember it by its four children (each at the 2x2 level). So next time you see an 8x8 node, when you calculate the next generation, you first check if you've already seen a node with those same four children. This is extended up through all levels of the quadtree, which gives you some pretty amazing optimizations if eg. you're 10 levels above the leaves. Unsurprisingly, it looks like the perfmance crux of this is the lookup of nodes by child-node values. Currently I have a hashmap of {&upper_left_node,&upper_right_node,&lower_left_node,&lower_right_node} -> node So my lookup function is this: func FindNode(ul, ur, ll, lr *Node) *Node { var node *Node var ok bool nc := NodeChildren{ul, ur, ll, lr} node, ok = NodeMap[nc] if ok { return node } node = &Node{ul, ur, ll, lr, 0, ul.Level + 1, nil} NodeMap[nc] = node return node } What I'm trying to figure out is if the "nc := NodeChildren..." line causes a memory allocation each time the function is called. If it does, can I/should I move the declaration to the global scope and just modify the values each time this function is called? Or is there a more efficient way to do this? Any advice/feedback would be welcome. (even coding style nits; this is literally the first thing I've written in Go so I'd love any feedback)

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  • Hogyan konfiguráljunk egy Oracle BI cluster rendszert Sun hardver környezetben

    - by Fekete Zoltán
    A következo Deploying Oracle® Business Intelligence Enterprise Edition on Oracle's Sun Systems white paper részletesen leírja, hogyan állítsunk össze egy Oracle BI klasztert. Ezzel a klaszter környezettel elérheto: - nagy rendelkezésre állás, az egyik szerver meghibásodásakor is muködik tovább a rendszer - terhelésmegosztás a BI szerverek között, aktív-aktív szereppel A dokumentum kitér mind a hardver mind a szoftver komponensek architektúrájára és konfigurálására, még az installálásra is: - hardver komponensek kapcsolatára: a két Oracle Business intelligence Sun SPARC Enterprise szerver, a switch, a Sun Unified Storage,... - szoftver komponensek: Oracle BI EE, WebLogic Server, Oracle Directory Server, Oracle Database, Oracle VM Server for SPARC, stb. Deploying Oracle® Business Intelligence Enterprise Edition on Oracle's Sun Systems

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  • Webcast: New Features of Solaris 11.1 and Solaris Cluster 4.1

    - by Jeff Victor
    If you missed last week's webcast of the new features in Oracle Solaris 11.1 you can view the recording. The speakers discuss changes that improve performance and scalability, particularly for Oracle DB, and many other enhancements. New features include Optimized Shared Memory (improves DB startup time), accelerated kernel locks (improves Oracle RAC performance and scalability), virtual memory improvements, a DTrace data collecter in the DB, Zones installed on Shared Storage (simplifies migration), Data Center Bridging, and Edge Virtual Bridging. To view the archived webcast, you must register and use the URL that you receive in e-mail.

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  • Version hash to solve Event Sourcing problems

    - by SystematicFrank
    The basic examples I have seen about Event Sourcing do not deal with out of order events, clock offsets in different systems and late events from system partitions. I am wondering if more polished Event Sourcing implementations rely on a version stamp of modified objects? For example, assuming that the system is rendering the entity Client with version id ABCD1234. If the user modifies the entity, the system will create an event with the modified fields AND the version id reference to which version it applies. Later the event responder would detect out of order events and merge them.

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