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  • What are the most important aspects to consider when choosing a SAN for a small office virtualizatio

    - by Prof. Moriarty
    I am in the process of consolidating 6 physical servers running 6 different operating system flavors (don't ask) into two identical physical servers (Dell PowerEdge 2900), using the free VMware ESXi 4.0 platform. We will install an iSCSI SAN over a 1GbE network, and store all virtual machine images on the SAN. Each physical server would run 3 VMs, and in the case of a physical server failure, we would manually switch over the other 3. These are all internal servers, while important, they can tolerate some amount of downtime (say <1h) to keep cost and complexity associated with HA down. I now need to choose the SAN to be used for the setup, on a low budget. We currently have about 2TB of data, but of course I want to able to grow, do backups of VM snapshots on other drives and remove them to a different location, etc. So what I would like to know is: Which are the must have features for this setup, without which using a SAN is not worth it? We are mostly a Dell shop, so I have been looking at the EqualLogic PS4000E High Availability model. Any opinions, anecdotes, bad experiences with this model? (This is one of the few models which could accomodate our existing disks from the physical servers.) If you can recommend something that is not Dell, but it has better value, I would most definitely consider it. Caveats, things to look out for?

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  • Faster integer division when denominator is known?

    - by aaa
    hi I am working on GPU device which has very high division integer latency, several hundred cycles. I am looking to optimize divisions. All divisions by denominator which is in a set { 1,3,6,10 }, however numerator is a runtime positive value, roughly 32000 or less. due to memory constraints, lookup table is not option. Can you think of alternatives? I have thought of computing float point inverses, and using those to multiply numerator. Thanks

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  • Any chance to get Core Data using Tokyo Cabinet as the persistent store?

    - by dontWatchMyProfile
    I watched a free high quality video with Aaron Hillegass about Core Data vs Tokyo Cabinet. Besides that this guy is amazingly funny (really, if you want to laugh now, watch it!), he shows off Tokyo Cabinet beeing about 40x faster than Core Data. I wonder if it's worth thinking about how to attach this to Core Data? Does that make any sense? Maybe as a custom atomic store or something like this?

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  • Any success using Apache Thrift on iPhone?

    - by jhs
    Has anybody done or seen a deployment of Apache Thrift in an iPhone app? I am wondering if is a reasonable solution for a high-volume, low(er)-latency network service for iPhones compared to HTTP. One noteworthy thing I found is a bug report about running Thrift on the iPhone, which seems to have been fixed. But that doesn't necessarily indicate that it's a done deal.

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  • What bugs apply to the different FindBugs reportLevels?

    - by Daniel H
    According to the Ant task, the report level is a low/medium/high setting that would look for bugs of different criticallity levels. However, there isn't anything I could find that explains which of the bugs apply to these different reporting levels. Is there somewhere that provides this, even if it is something I need to look at within the source?

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  • can widgets be cached ?

    - by movieuser
    Is there a way to cache widgets. For example if you place your widgets on high volume websites then each time when someone access that site, a call will be made to your server to get the widget code. This way my server can get too much overloaded just to display the widget . Can I cache the widget HTML code and place it on some server like Akamai. Any suggestions or tips highly appreciated. Thanks in advance.

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  • getting Ceil() of Decimal in python?

    - by Gunjan
    Is there a way to get the ceil of a high precision Decimal in python? >>> import decimal; >>> decimal.Decimal(800000000000000000001)/100000000000000000000 Decimal('8.00000000000000000001') >>> math.ceil(decimal.Decimal(800000000000000000001)/100000000000000000000) 8.0 math rounds the value and returns non precise value

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  • Are open source projects considered community service?

    - by Gio Borje
    I'm currently a junior in high school and I've been slacking off on my community service to develop websites and do some personal projects in C#. Currently, I'm developing an web-based IM-Chat through node.js (the server-side Javascript). If I were to post this or other projects on Github or on Google Code, could this be considered community service?—to the programming community?

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  • What should be the considerations for choosing SQL/NoSQL?

    - by Yuval A
    Target application is a medium-sized website built to support several hundred-thousand users an hour, with an option to scale above that. Data model is rather simple, and caching potential is pretty high (~10:1 ratio of read to edit actions). What should be the considerations when coming to choose between a relational, SQL-based datastore to a NoSQL option (such as HBase and Cassandra)?

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  • Cocoa: Creating a Window with a Variable Number of Interface Elements

    - by Rui Pacheco
    Hi, I've a window that will have an unknown amount of text fields, determined by the content of a remote server. In high level terms, how should I go about this? Create a custom view or create an empty window with a backing NSWindowController and then add stuff to it when the window is opened? I've seen the examples on the O'Reilly Cocoa book and those effectively create a custom NSView. Is this the right way to do it, 8 year later?

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  • Lamda functions in php

    - by Oden
    Hey, Im really interested in the way of using lamda functions. Does it make sense to use them in a high-level programming language? If yes, why? Is this really just a function embedded in a function, (Like this) or is there more behind?

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  • Robust and easy to implement serial bus (automotive application)

    - by JcMaco
    What serial communication bus would you use in a automotive embedded system if your main selection criteria were: * Electrically robust * Slow speed (32 kb/s) * Easy to program * Easy to interface with microcontrollers It won't be transferring much data, but it will need to be transferred periodically at high speed (100 - 500 Hz). I find that RS-232 is just not reliable enough if you have noise in your ground line. CAN-bus seems interesting, but I have no experience with it. We are currently interested in a combination of AVR AT90CAN128 microcontrollers.

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  • Arduino (processing) Library in Netbeans and control

    - by Casper Marcussen
    Hello everyone I am trying to control 4 LEDs and getting analog input from 4 contacts. The program is written in java, so to gain acces to the functions of arduino, such as AnalogRead() and setting an LED to high or low, would importing the processing library let the program use those functions? I was also wondering, if the program, will be transferred to the arduino it self, or the java program will just pull the data from the pins?

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  • inline block ie7 on h2

    - by Andy
    I think im going to kill someone high up in microsoft very very soon: Please can someone help me get my head around this bug: http://www.yellostudio.co.uk/tm/selection.html# I'd like the top h2 to display inline block alongside the help icons on the right. The issue only exists in ie7 and its doing my sweed in... Any help would be very very much appreciated

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  • What does this regex expression do?

    - by Ranjeet
    Hi All, I am looking after fixing a bug and there I find this expression:- directoryPath = Regex.Replace(directoryPath, "[^\\w\\.@-]", ""); but as a result of the expression all the high ascii characters in directory path are messed up, I am not good at regex and dont know about it but for now I have to fix the issue . Can someone please explain me what this regular expression does?

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  • SQL Server Database In Single User Mode after Failover

    - by jlichauc
    Here is a weird situation we experienced with a SQL Server 2008 Database Mirroring Failover. We have a pair of mirrored databases running in high-availability mode and both the principal and mirror showed as synchronized. As part of some maintenance I triggered a manual failover of the principal to the mirror. However after the failover the principal was now in single-user mode instead of the expected "Principal/Synchronized" state we usually get. The database had been in multi-user mode on the previous principal before this had happened. We ended up stopping all applications, restarting the SQL Server instances, and executing "ALTER DATABASE ... SET MULTI_USER" to bring the database back to the expected "Principal/Synchronized" state in a multi-user mode. Question. Does anyone know where SQL Server stores information about whether a database should be in single-user mode or not? I'm wondering if there is some system database or table that has this setting recorded somewhere. In particular we had an incident once with the database on the original principal (the one I was failing over to) where when trying to detach the database it was put into single-user mode. I'm wondering if that setting is cached somewhere and is the reason that SQL Server put it back into single-user mode after a failover.

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  • How many reverse proxies (nginx, haproxy) is too many?

    - by Alysum
    I'm setting up a HA (high availability) cluster using nginx, haproxy & apache. I've been reading great things about nginx and haproxy. People tend to choose one or the other but I like both. Haproxy is more flexible for load balancing than nginx's simple round robin (even with the upstream-fair patch). But I'd like to keep nginx for redirecting non-https to https among other things right at the point of entry to the cluster. On the other hand, nginx is a lot faster for serving static contents and would reduce the load on the powerful apache which loves to eat a lot of RAM! Here is my planned setup: Load balancer: nginx listens on port 80/443 and proxy_forwards to haproxy on 8080 on the same server to load balance between the multiple nodes. Nodes: nginx on the node listens to requests coming from haproxy on 8080, if the content is static, serve it. But if it's a backend script (in my case PHP), proxy forward to apache2 on the same node server listenning on a different port number. Technically this setup works but my concerns are whether having the requests going through several proxies is going to slow down requests? Most of the requests will be PHP requests as the backends are services (which means groing from nginx - haproxy - nginx - apache). Thoughts? Cheers

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  • Naming Suggestions For A Function Providing Chaining In A Different Way

    - by sid3k
    I've coded an experimental function which makes passed objects chainable by using high order functions. It's name is "chain" for now, and here is a usage example; chain("Hello World") (print) // evaluates print function by passing "Hello World" object. (console.log,"Optional","Parameters") (returnfrom) // returns "Hello World" It looks lispy but behaves very different since it's coded in a C based language, I don't know if there is a name for this idiom and I couldn't any name more suitable than "chain". Any ideas, suggestions?

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  • Changing Corosync/Heartbeat pair's active node based on MySQL/Galera cluster state

    - by Hace
    Background I'm planning on building a High Availability "cluster" for our Zabbix instance by placing two physical servers in one server room and two in another server room. In each server room one of the physical servers will run Zabbix on RHEL and the other will run Zabbix's MySQL database, also on RHEL. I'd prefer synchronous replication for the MySQL nodes so I'm planning on using Galera in a master-slave configuration. The Zabbix instances on the two Zabbix servers would be controlled by Heartbeat/Corosync (although Red Hat Cluster Suite is also an option...) If the Zabbix server in Server Room A goes down, the one in Server Room B becomes active (and vice versa). Ditto for the MySQL servers/instances. If either of those cases happen, however, the connection between the Zabbix server and the MySQL server becomes significantly slower as ti has to travel over WAN. Question Is it possible to configure the Heartbeat/CoroSync pair to instruct the MySQL/Galera cluster to change the master node to switch to (if available) the one that's in the server room as the active Heartbeat/Corosync -node and (more challengingly) is it possible to do the same in the other direction, i.e have the Galera cluster change the active Heartbeat/CoroSync server to be in the same room as the active MySQL master server in case of a failover in over to avoid unnecessary WAN transfers between the application and its DB? Theories Most likely I can get CoroSync to run something that'd log in to one of the DB nodes to change the MySQL/Galera master but I don't know if it's really possible to do anything similar in the other direction in Galera. Is it possible to define a "service" in CoroSync/Heartbeat so that both the service and its MySQL service would migrate as one if possible. Using the DB server that's behind WAN should still be a better option to DB downtime. Am I just using too many tools to solve a problem that'd be far simpler with something else?

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  • Java socketserver: How to handle many incoming connections?

    - by SlappyTheFish
    I am writing a simple multithreaded socketserver and I am wondering how best to handle incoming connections: create a new thread for each new connection. The number of concurrent threads would be limited and waiting connections limited by specifying a backlog add all incoming connections into a queue and have a pool of worker threads that process the queue I am inclined to go for option 2 because I really don't want to refuse any connections, even under high loads, but I am wondering if there are any considerations I should be aware of with accepting effectively unlimited connections?

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