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  • Memory limiting solutions for greedy applications that can crash OS?

    - by Hooked
    I use my computer for scientific programming. It has a healthy 8GB of RAM and 12GB of swap space. Often, as my problems have gotten larger, I exceed all of the available RAM. Rather than crashing (which would be preferred), it seems Ubuntu starts loading everything into swap, including Unity and any open terminals. If I don't catch a run-away program in time, there is nothing I can do but wait - it takes 4-5 minutes to switch to a command prompt eg. Ctrl-Alt-F2 where I can kill the offending process. Since my own stupidity is out of scope of this forum, how can I prevent Ubuntu from crashing via thrashing when I use up all of the available memory from a single offending program? At-home experiment*! Open a terminal, launch python and if you have numpy installed try this: >>> import numpy >>> [numpy.zeros((10**4, 10**4)) for _ in xrange(50)] * Warning: may have adverse effects, monitor the process via iotop or top to kill it in time. If not, I'll see you after your reboot.

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  • Using Queries with Coherence Read-Through Caches

    - by jpurdy
    Applications that rely on partial caches of databases, and use read-through to maintain those caches, have some trade-offs if queries are required. Coherence does not support push-down queries, so queries will apply only to data that currently exists in the cache. This is technically consistent with "read committed" semantics, but the potential absence of data may make the results so unintuitive as to be useless for most use cases (depending on how much of the database is held in cache). Alternatively, the application itself may manually "push down" queries to the database, either retrieving results equivalent to querying the cache directly, or may query the database for a key set and read the values from the cache (relying on read-through to handle any missing values). Obviously, if the result set is too large, reading through the cache may cause significant thrashing. It's also worth pointing out that if the cache is asynchronously synchronized with the database (perhaps via database change listener), that an application may commit a transaction to the database, then generate a key set from the database via a query, then read cache entries through the cache, possibly resulting in a race condition where the application sees older data than it had previously committed. In theory this is not problematic but in practice it is very unintuitive. For this reason it often makes sense to invalidate the cache when updating the database, forcing the next read-through to update the cache.

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  • Using Bulk Operations with Coherence Off-Heap Storage

    - by jpurdy
    Some NamedCache methods (including clear(), entrySet(Filter), aggregate(Filter, …), invoke(Filter, …)) may generate large intermediate results. The size of these intermediate results may result in out-of-memory exceptions on cache servers, and in some cases on cache clients. This may be particularly problematic if out-of-memory exceptions occur on more than one server (since these operations may be cluster-wide) or if these exceptions cause additional memory use on the surviving servers as they take over partitions from the failed servers. This may be particularly problematic with clusters that use off-heap storage (such as NIO or Elastic Data storage options), since these storage options allow greater than normal cache sizes but do nothing to address the size of intermediate results or final result sets. One workaround is to use a PartitionedFilter, which allows the application to break up a larger operation into a number of smaller operations, each targeting either a set of partitions (useful for reducing the load on each cache server) or a set of members (useful for managing client result set sizes). It is also possible to return a key set, and then pull in the full entries using that key set. This also allows the application to take advantage of near caching, though this may be of limited value if the result is large enough to result in near cache thrashing.

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  • C++ Profiling: KiFastSystemCallRet

    - by John
    I searched for this after seeing it's the top rated item when profiling using Very Sleepy, and it seems everyone gets the answer "it's a system function, ignore it". But Sleepy's hint for the function says: Hint: KiFastSystemCallRet often means the thread was waiting for something else to finish. Possible causes might be disk I/O, waiting for an event, or maybe just calling Sleep(). Now, my app is absolutely thrashing the CPU and so it's a bit weird 33% of the time is spent waiting for something to happen. Do I really just ignore it? EDIT: apparently, 77% of the calls to this come from QueryOglResource (?) which is in module nvd3dnum. I think that might be nvidia Direct3D stuff, i.e rendering.

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  • Disk-based caching of dynamic images in IIS 7

    - by Daniel Schierbeck
    I'm writing an image server which needs to handle a relatively large number of concurrent requests (~5,000). The images being served are dynamically scaled down and cropped based on per-image specifications, which are queried from a database. The number of images is rather large, so an in-memory cache isn't viable (thrashing would most definitely occur). I'm using native caching in IIS 7 to avoid hitting the ASP.NET app which generates the images on-the-fly. I've looked around, but I couldn't find a simple way to configure IIS to store the cache on-disk -- is there such an option, or would I need to roll my own? I'd rather avoid placing the generated images in a public folder, so they can be served statically, since I would prefer to invalidate the cache entries using a query parameter (last-edit time from the database,) which doesn't seem possible to reconcile with static caching. I would love to get some feedback on this!

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  • Getting a virus is *very* annoying

    - by bconlon
    I spent most of yesterday removing an annoying virus from my PC. I feel slightly foolish for getting one in the first place, but after so many years I guess I was always going to eventually succumb. I was also a little surprised at the failure of various tools at removing it. The virus would redirect the browser to websites including ‘licosearch’, ‘hugosearch’ and ‘facebook’, and the disk would be thrashing away infecting dlls in some way. I had the full up to date version of McAfee installed. This identified that there was an issue in some dlls on the system and was able to ‘fix’ them. But they kept getting re-infected. So I installed Microsoft Security Essentials and this too was able to identify and ‘fix’ the infected dlls. The system scans take forever and I really expected better results. I also tried Malwarebytes, Hitman Pro, AVG and Sophos to no avail. Eventually I thought I’d investigate myself. It turned out that on reboot, the virus would start 3 instances of Firefox.exe which I’m guessing would do bad things including infecting as many dlls on the system as possible. I removed Firefox and the virus cleverly then launched 3 instances of Chrome! So I uninstalled Chrome and yes, it then started to launch 3 instances of iexplore.exe. If I’m honest, by this stage I was just seeing if it would be able to use any of the browsers! As it was starting these on reboot, I looked in my User Startup folder and there was a <randomly named>.exe and several log files. I deleted these and rebooted. When I looked they had been recreated. So I then looked in the registry Run and RunOnce entries: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run. Sure enough there were entries to run a file in C:\Program Files\<random name folder>\<random name file>.exe. I deleted this and rebooted and it was fixed. I also looked in the event log and found a warning that Winlogon had failed to start the file C:\Program Files\<random name folder>\<random name file>.exe So I also checked HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon and this entry had also been changed. Finally I ran a full system scan to clean up any infected dlls. I hope it’s gone for good!  #

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  • Have local admin privileges on Windows XP, but getting "Error terminating process: Access is denied"

    - by Chris W. Rea
    On one of the Windows XP machines I use regularly, there is a process that starts up periodically. I'd like to be able to kill the process – sometimes – because it occasionally runs when I'm busy doing something machine-intensive. I've already tried dropping the process priority to "Idle" to mitigate the effects, but it isn't the CPU that's the problem. Rather, the process is very disk-intensive and no matter the process priority, it still causes significant disk thrashing when running, impacting everything else I'm doing at the time. Using Process Explorer, I can find the process, right-click, and choose Kill Process, but I always get the message "Error terminating process: Access is denied." This is not an operating system process, but third-party software. What might that process be doing to prevent itself from being terminated? How can I kill such a process? Is there a way for me to modify the process's security or access control list (ACL) somewhere, using Process Explorer or another tool, so that I can effectively kill it?

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  • Cassandra random read speed

    - by Jody Powlette
    We're still evaluating Cassandra for our data store. As a very simple test, I inserted a value for 4 columns into the Keyspace1/Standard1 column family on my local machine amounting to about 100 bytes of data. Then I read it back as fast as I could by row key. I can read it back at 160,000/second. Great. Then I put in a million similar records all with keys in the form of X.Y where X in (1..10) and Y in (1..100,000) and I queried for a random record. Performance fell to 26,000 queries per second. This is still well above the number of queries we need to support (about 1,500/sec) Finally I put ten million records in from 1.1 up through 10.1000000 and randomly queried for one of the 10 million records. Performance is abysmal at 60 queries per second and my disk is thrashing around like crazy. I also verified that if I ask for a subset of the data, say the 1,000 records between 3,000,000 and 3,001,000, it returns slowly at first and then as they cache, it speeds right up to 20,000 queries per second and my disk stops going crazy. I've read all over that people are storing billions of records in Cassandra and fetching them at 5-6k per second, but I can't get anywhere near that with only 10mil records. Any idea what I'm doing wrong? Is there some setting I need to change from the defaults? I'm on an overclocked Core i7 box with 6gigs of ram so I don't think it's the machine. Here's my code to fetch records which I'm spawning into 8 threads to ask for one value from one column via row key: ColumnPath cp = new ColumnPath(); cp.Column_family = "Standard1"; cp.Column = utf8Encoding.GetBytes("site"); string key = (1+sRand.Next(9)) + "." + (1+sRand.Next(1000000)); ColumnOrSuperColumn logline = client.get("Keyspace1", key, cp, ConsistencyLevel.ONE); Thanks for any insights

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  • JSESSIONID collision between two servers on same ip but different ports

    - by Steve Armstrong
    I've got a situation where I have two different webapps running on a single server, using different ports. They're both running Java's Jetty servlet container, so they both use a cookie parameter named JSESSIONID to track the session id. These two webapps are fighting over the session id. Open a Firefox tab, and go to WebApp1 WebApp1's HTTP response has a set-cookie header with JSESSIONID=1 Firefox now has a Cookie header with JSESSIONID=1 in all it's HTTP requests to WebApp1 Open a second Firefox tab, and go to WebApp2 The HTTP reqeust to WebApp2 also has a Cookie header with JSESSIONID=1, but in the doGet, when I call req.getSession(false); I get null. And if I call req.getSession(true) I get a new Session object, but then the HTTP response from WebApp2 has a set-cookie header with JSESSIONID=20 Now, WebApp2 has a working Session, but WebApp1's session is gone. Going to WebApp1 will give me a new session, blowing away WebApp2's session. Continue forever So the Sessions are thrashing between each web app. I'd really like for the req.getSession(false) to return a valid session if there's already a JSESSIONID cookie defined. One option is to basically reimplement the Session framework with a HashMap and cookies called WEBAPP1SESSIONID and WEBAPP2SESSIONID, but that sucks, and means I'll have to hack the new Session stuff into ActionServlet and a few other places. This must be a problem others have encountered. Is Jetty's HttpServletRequest.getSession(boolean) just crappy?

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  • Event ID 17890 (A significant part... paged out.) with SQL Server 2008

    - by Godeke
    I have a machine that has SQL Server 2008 Standard installed. Periodically (about once an hour) I am getting Event ID 17890 several times in a row. An example: 6:28:54 "A significant part of sql server process memory has been paged out. This may result in a performance degradation. Duration: 0 seconds. Working set (KB): 10652, committed (KB): 628428, memory utilization: 1%%. 6:34:27 "A significant part of sql server process memory has been paged out. This may result in a performance degradation. Duration: 332 seconds. Working set (KB): 169780, committed (KB): 546124, memory utilization: 31%%." 6:38:55 "A significant part of sql server process memory has been paged out. This may result in a performance degradation. Duration: 600 seconds. Working set (KB): 245068, committed (KB): 546124, memory utilization: 44%%." This pattern repeated at 7:26 - 7:37, 8:26 - 8:36, 9:24 - 9:35 and so with the same increasing working set and memory utilization pattern. I don't have any (known) background tasks running at this time. Backups run at 2:00 This subsided from 11:00 at night until it resumed at 4:00 in the morning and has been continuing the intermittent 10 minute glitch periods. As this server has plenty of RAM (the commit charge has peaked at 2,871,564 of 4,194,012 physical) I disabled the paging files after reading several items I dug up searching Google and not finding any of them changing the situation. This pattern I am documented is after removing the paging files, so I'm not even sure where we are paging the SQL process could be going. I also changed the SQL process memory to have a minimum of 500MB and a maximum of 2GB of RAM (as this is a light duty database server serving only a small workgroup). Has anyone encountered this? Prior to disabling the page files this error would cause 5 minutes of disk thrashing that disabled access to the databases, files, IIS webs and so on. Since disabling the page files it just logs strange things, but I'm not seeing a performance drop at least. Any suggestions would be welcome.

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  • Documentation Changes in Solaris 11.1

    - by alanc
    One of the first places you can see Solaris 11.1 changes are in the docs, which have now been posted in the Solaris 11.1 Library on docs.oracle.com. I spent a good deal of time reviewing documentation for this release, and thought some would be interesting to blog about, but didn't review all the changes (not by a long shot), and am not going to cover all the changes here, so there's plenty left for you to discover on your own. Just comparing the Solaris 11.1 Library list of docs against the Solaris 11 list will show a lot of reorganization and refactoring of the doc set, especially in the system administration guides. Hopefully the new break down will make it easier to get straight to the sections you need when a task is at hand. Packaging System Unfortunately, the excellent in-depth guide for how to build packages for the new Image Packaging System (IPS) in Solaris 11 wasn't done in time to make the initial Solaris 11 doc set. An interim version was published shortly after release, in PDF form on the OTN IPS page. For Solaris 11.1 it was included in the doc set, as Packaging and Delivering Software With the Image Packaging System in Oracle Solaris 11.1, so should be easier to find, and easier to share links to specific pages the HTML version. Beyond just how to build a package, it includes details on how Solaris is packaged, and how package updates work, which may be useful to all system administrators who deal with Solaris 11 upgrades & installations. The Adding and Updating Oracle Solaris 11.1 Software Packages was also extended, including new sections on Relaxing Version Constraints Specified by Incorporations and Locking Packages to a Specified Version that may be of interest to those who want to keep the Solaris 11 versions of certain packages when they upgrade, such as the couple of packages that had functionality removed by an (unusual for an update release) End of Feature process in the 11.1 release. Also added in this release is a document containing the lists of all the packages in each of the major package groups in Solaris 11.1 (solaris-desktop, solaris-large-server, and solaris-small-server). While you can simply get the contents of those groups from the package repository, either via the web interface or the pkg command line, the documentation puts them in handy tables for easier side-by-side comparison, or viewing the lists before you've installed the system to pick which one you want to initially install. X Window System We've not had good X11 coverage in the online Solaris docs in a while, mostly relying on the man pages, and upstream X.Org docs. In this release, we've integrated some X coverage into the Solaris 11.1 Desktop Adminstrator's Guide, including sections on installing fonts for fontconfig or legacy X11 clients, X server configuration, and setting up remote access via X11 or VNC. Of course we continue to work on improving the docs, including a lot of contributions to the upstream docs all OS'es share (more about that another time). Security One of the things Oracle likes to do for its products is to publish security guides for administrators & developers to know how to build systems that meet their security needs. For Solaris, we started this with Solaris 11, providing a guide for sysadmins to find where the security relevant configuration options were documented. The Solaris 11.1 Security Guidelines extend this to cover new security features, such as Address Space Layout Randomization (ASLR) and Read-Only Zones, as well as adding additional guidelines for existing features, such as how to limit the size of tmpfs filesystems, to avoid users driving the system into swap thrashing situations. For developers, the corresponding document is the Developer's Guide to Oracle Solaris 11 Security, which has been the source for years for documentation of security-relevant Solaris API's such as PAM, GSS-API, and the Solaris Cryptographic Framework. For Solaris 11.1, a new appendix was added to start providing Secure Coding Guidelines for Developers, leveraging the CERT Secure Coding Standards and OWASP guidelines to provide the base recommendations for common programming languages and their standard API's. Solaris specific secure programming guidance was added via links to other documentation in the product doc set. In parallel, we updated the Solaris C Libary Functions security considerations list with details of Solaris 11 enhancements such as FD_CLOEXEC flags, additional *at() functions, and new stdio functions such as asprintf() and getline(). A number of code examples throughout the Solaris 11.1 doc set were updated to follow these recommendations, changing unbounded strcpy() calls to strlcpy(), sprintf() to snprintf(), etc. so that developers following our examples start out with safer code. The Writing Device Drivers guide even had the appendix updated to list which of these utility functions, like snprintf() and strlcpy(), are now available via the Kernel DDI. Little Things Of course all the big new features got documented, and some major efforts were put into refactoring and renovation, but there were also a lot of smaller things that got fixed as well in the nearly a year between the Solaris 11 and 11.1 doc releases - again too many to list here, but a random sampling of the ones I know about & found interesting or useful: The Privileges section of the DTrace Guide now gives users a pointer to find out how to set up DTrace privileges for non-global zones and what limitations are in place there. A new section on Recommended iSCSI Configuration Practices was added to the iSCSI configuration section when it moved into the SAN Configuration and Multipathing administration guide. The Managing System Power Services section contains an expanded explanation of the various tunables for power management in Solaris 11.1. The sample dcmd sources in /usr/demo/mdb were updated to include ::help output, so that developers like myself who follow the examples don't forget to include it (until a helpful code reviewer pointed it out while reviewing the mdb module changes for Xorg 1.12). The README file in that directory was updated to show the correct paths for installing both kernel & userspace modules, including the 64-bit variants.

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  • Data Source Connection Pool Sizing

    - by Steve Felts
    Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman","serif";} One of the most time-consuming procedures of a database application is establishing a connection. The connection pooling of the data source can be used to minimize this overhead.  That argues for using the data source instead of accessing the database driver directly. Configuring the size of the pool in the data source is somewhere between an art and science – this article will try to move it closer to science.  From the beginning, WLS data source has had an initial capacity and a maximum capacity configuration values.  When the system starts up and when it shrinks, initial capacity is used.  The pool can grow to maximum capacity.  Customers found that they might want to set the initial capacity to 0 (more on that later) but didn’t want the pool to shrink to 0.  In WLS 10.3.6, we added minimum capacity to specify the lower limit to which a pool will shrink.  If minimum capacity is not set, it defaults to the initial capacity for upward compatibility.   We also did some work on the shrinking in release 10.3.4 to reduce thrashing; the algorithm that used to shrink to the maximum of the currently used connections or the initial capacity (basically the unused connections were all released) was changed to shrink by half of the unused connections. The simple approach to sizing the pool is to set the initial/minimum capacity to the maximum capacity.  Doing this creates all connections at startup, avoiding creating connections on demand and the pool is stable.  However, there are a number of reasons not to take this simple approach. When WLS is booted, the deployment of the data source includes synchronously creating the connections.  The more connections that are configured in initial capacity, the longer the boot time for WLS (there have been several projects for parallel boot in WLS but none that are available).  Related to creating a lot of connections at boot time is the problem of logon storms (the database gets too much work at one time).   WLS has a solution for that by setting the login delay seconds on the pool but that also increases the boot time. There are a number of cases where it is desirable to set the initial capacity to 0.  By doing that, the overhead of creating connections is deferred out of the boot and the database doesn’t need to be available.  An application may not want WLS to automatically connect to the database until it is actually needed, such as for some code/warm failover configurations. There are a number of cases where minimum capacity should be less than maximum capacity.  Connections are generally expensive to keep around.  They cause state to be kept on both the client and the server, and the state on the backend may be heavy (for example, a process).  Depending on the vendor, connection usage may cost money.  If work load is not constant, then database connections can be freed up by shrinking the pool when connections are not in use.  When using Active GridLink, connections can be created as needed according to runtime load balancing (RLB) percentages instead of by connection load balancing (CLB) during data source deployment. Shrinking is an effective technique for clearing the pool when connections are not in use.  In addition to the obvious reason that there times where the workload is lighter,  there are some configurations where the database and/or firewall conspire to make long-unused or too-old connections no longer viable.  There are also some data source features where the connection has state and cannot be used again unless the state matches the request.  Examples of this are identity based pooling where the connection has a particular owner and XA affinity where the connection is associated with a particular RAC node.  At this point, WLS does not re-purpose (discard/replace) connections and shrinking is a way to get rid of the unused existing connection and get a new one with the correct state when needed. So far, the discussion has focused on the relationship of initial, minimum, and maximum capacity.  Computing the maximum size requires some knowledge about the application and the current number of simultaneously active users, web sessions, batch programs, or whatever access patterns are common.  The applications should be written to only reserve and close connections as needed but multiple statements, if needed, should be done in one reservation (don’t get/close more often than necessary).  This means that the size of the pool is likely to be significantly smaller then the number of users.   If possible, you can pick a size and see how it performs under simulated or real load.  There is a high-water mark statistic (ActiveConnectionsHighCount) that tracks the maximum connections concurrently used.  In general, you want the size to be big enough so that you never run out of connections but no bigger.   It will need to deal with spikes in usage, which is where shrinking after the spike is important.  Of course, the database capacity also has a big influence on the decision since it’s important not to overload the database machine.  Planning also needs to happen if you are running in a Multi-Data Source or Active GridLink configuration and expect that the remaining nodes will take over the connections when one of the nodes in the cluster goes down.  For XA affinity, additional headroom is also recommended.  In summary, setting initial and maximum capacity to be the same may be simple but there are many other factors that may be important in making the decision about sizing.

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  • Why does Process Explorer cause highly targeted failure of some applications / basic UI functions in a high-power EC2 Windows instance?

    - by Dan Nissenbaum
    Update: I have determined that Process Explorer itself - the program I am using to debug a performance issue - seems to be the cause of the issue. See note, with updated question, at end. I am running a high-power (cc2.8xlarge) Amazon AWS EC2 Windows instance off of a boot EBS volume, provisioned at 2500 PIOPS, which was created from a snapshot of a previous boot volume. My purpose with the instance is to use it as a development workstation with many developer tools installed, such as Visual Studio, a local XAMPP stack, etc. I have upwards of 40 programs installed on the machine. The usability of the instance as a development machine often works quite well. The RDP lag is adequately small. I have used it for hours on end without problems for some of my most intense development tasks. As a result, I have just purchased a reserved instance, and I opted to rebuild my development machine starting from scratch with a Windows Server 2012 AMI. After having installed all of my desired/required applications for development over this past week, again the machine seems to often work well and I have worked for up to an hour at a time without problems doing heavy development work. However, I continue to run into catastrophic OS usability issues that may prevent me from being able to rely on this machine as a development machine. I would like to track down the source of the problem, if there is an easily identifiable source. (Update: I have tracked down the source to be Process Explorer, the very program I was using to debug the problem. See update at end.) The issues are as follows. (These are some primary examples) Some applications, after a period of adequate responsiveness, suddenly begin to respond very, very slowly to basic user interface actions such as clicking on menus and pressing Ctrl-Tab to switch between open documents. Two examples are UltraEdit and PhpEd. It typically takes ~2 seconds for a menu to appear, and ~4 seconds to switch between open documents. Additionally, insertion point motion in the editor is lagged by upwards of ~2 seconds. Process Explorer, which I am using to help debug the problem, seems to run acceptably for a couple of minutes, but on multiple occasions Process Explorer itself hangs completely. It hangs at the same time as the problems noted above. When it hangs, it is 100% unresponsive. Clicking on its taskbar icon neither causes it to come to the top or go behind, and its viewable area is filled with nothing but a region partially containing pure white and partially containing incomplete windows widgets that are unreadable, and that never change. Waiting 10 minutes does not clear the problem. Attempting to force-quit Process Explorer by right-clicking on its taskbar icon and choosing "Close Window" takes about 5 full minutes to exit (Process Explorer itself can't be used to exit Process Explorer, and it is registered as a Task Manager substitute). Other programs work just fine during this time. For example, Chrome tabs flip very quickly back and forth, menus pop open instantly, web pages load quickly, and typing in forms/web applications inside the browser works promptly. Another example of an application that works crisply is Filemaker - its menus open instantly, and switching views in this application occurs promptly. Other applications also work without issue. Also, switching between applications occurs promptly as well. It is only a handful of applications that exhibit the problem, with some primary examples given above. At first I thought that EBS IOPS might be a problem. Therefore, I ran Performance Monitor, and watched the "Disk Transfers/sec" monitor in real time. At no point did this measure come anywhere close to hitting the 2500 PIOPS provisioned for the EBS volume. The RAM was also well under the limit (~10 GB used out of 60 GB). I did notice that one CPU core (out of 32 logical cores) was fully thrashing at 100% (i.e., ~3.1%) during the problematic periods. This seems to indicate that a single CPU core is handling the menus / flipping between open documents (for some applications only) / managing the Process Explorer user interface, and that this single core was hosed for some reason during the problematic periods. Also note that I have a desktop workstation (Windows 7) that I also use as a development machine, via a remote connection, with a nearly identical set of programs installed, and this desktop workstation does not exhibit any of the problems I've discussed above. I have been using it heavily for well over a year now. Any suggestions regarding either the source of the problem, or steps I might take to investigate the source of the problem, would be appreciated. Thanks. Note: After extensive testing & investigation, I have noticed that when I quit Process Explorer, the problem vanishes and the system performance returns to normal, and then reappears quickly when I run Process Explorer again (note: again, the performance problems only appear for a subset of applications - other applications work perfectly fine during the same period). My question is therefore (thankfully) more specific: Why does Process Explorer cause highly targeted failure of some applications (including itself) and basic UI functions, in a high-power EC2 Windows instance?

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  • How to sanely configure security policy in Tomcat 6

    - by Chas Emerick
    I'm using Tomcat 6.0.24, as packaged for Ubuntu Karmic. The default security policy of Ubuntu's Tomcat package is pretty stringent, but appears straightforward. In /var/lib/tomcat6/conf/policy.d, there are a variety of files that establish default policy. Worth noting at the start: I've not changed the stock tomcat install at all -- no new jars into its common lib directory(ies), no server.xml changes, etc. Putting the .war file in the webapps directory is the only deployment action. the web application I'm deploying fails with thousands of access denials under this default policy (as reported to the log thanks to the -Djava.security.debug="access,stack,failure" system property). turning off the security manager entirely results in no errors whatsoever, and proper app functionality What I'd like to do is add an application-specific security policy file to the policy.d directory, which seems to be the recommended practice. I added this to policy.d/100myapp.policy (as a starting point -- I would like to eventually trim back the granted permissions to only what the app actually needs): grant codeBase "file:${catalina.base}/webapps/ROOT.war" { permission java.security.AllPermission; }; grant codeBase "file:${catalina.base}/webapps/ROOT/-" { permission java.security.AllPermission; }; grant codeBase "file:${catalina.base}/webapps/ROOT/WEB-INF/-" { permission java.security.AllPermission; }; grant codeBase "file:${catalina.base}/webapps/ROOT/WEB-INF/lib/-" { permission java.security.AllPermission; }; grant codeBase "file:${catalina.base}/webapps/ROOT/WEB-INF/classes/-" { permission java.security.AllPermission; }; Note the thrashing around attempting to find the right codeBase declaration. I think that's likely my fundamental problem. Anyway, the above (really only the first two grants appear to have any effect) almost works: the thousands of access denials are gone, and I'm left with just one. Relevant stack trace: java.security.AccessControlException: access denied (java.io.FilePermission /var/lib/tomcat6/webapps/ROOT/WEB-INF/classes/com/foo/some-file-here.txt read) java.security.AccessControlContext.checkPermission(AccessControlContext.java:323) java.security.AccessController.checkPermission(AccessController.java:546) java.lang.SecurityManager.checkPermission(SecurityManager.java:532) java.lang.SecurityManager.checkRead(SecurityManager.java:871) java.io.File.exists(File.java:731) org.apache.naming.resources.FileDirContext.file(FileDirContext.java:785) org.apache.naming.resources.FileDirContext.lookup(FileDirContext.java:206) org.apache.naming.resources.ProxyDirContext.lookup(ProxyDirContext.java:299) org.apache.catalina.loader.WebappClassLoader.findResourceInternal(WebappClassLoader.java:1937) org.apache.catalina.loader.WebappClassLoader.findResource(WebappClassLoader.java:973) org.apache.catalina.loader.WebappClassLoader.getResource(WebappClassLoader.java:1108) java.lang.ClassLoader.getResource(ClassLoader.java:973) I'm pretty convinced that the actual file that's triggering the denial is irrelevant -- it's just some properties file that we check for optional configuration parameters. What's interesting is that: it doesn't exist in this context the fact that the file doesn't exist ends up throwing a security exception, rather than java.io.File.exists() simply returning false (although I suppose that's just a matter of the semantics of the read permission). Another workaround (besides just disabling the security manager in tomcat) is to add an open-ended permission to my policy file: grant { permission java.security.AllPermission; }; I presume this is functionally equivalent to turning off the security manager. I suppose I must be getting the codeBase declaration in my grants subtly wrong, but I'm not seeing it at the moment.

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  • Why Are Minimized Programs Often Slow to Open Again?

    - by Jason Fitzpatrick
    It seems particularly counterintuitive: you minimize an application because you plan on returning to it later and wish to skip shutting the application down and restarting it later, but sometimes maximizing it takes even longer than launching it fresh. What gives? Today’s Question & Answer session comes to us courtesy of SuperUser—a subdivision of Stack Exchange, a community-driven grouping of Q&A web sites. The Question SuperUser reader Bart wants to know why he’s not saving any time with application minimization: I’m working in Photoshop CS6 and multiple browsers a lot. I’m not using them all at once, so sometimes some applications are minimized to taskbar for hours or days. The problem is, when I try to maximize them from the taskbar – it sometimes takes longer than starting them! Especially Photoshop feels really weird for many seconds after finally showing up, it’s slow, unresponsive and even sometimes totally freezes for minute or two. It’s not a hardware problem as it’s been like that since always on all on my PCs. Would I also notice it after upgrading my HDD to SDD and adding RAM (my main PC holds 4 GB currently)? Could guys with powerful pcs / macs tell me – does it also happen to you? I guess OSes somehow “focus” on active software and move all the resources away from the ones that run, but are not used. Is it possible to somehow set RAM / CPU / HDD priorities or something, for let’s say, Photoshop, so it won’t slow down after long period of inactivity? So what is the deal? Why does he find himself waiting to maximize a minimized app? The Answer SuperUser contributor Allquixotic explains why: Summary The immediate problem is that the programs that you have minimized are being paged out to the “page file” on your hard disk. This symptom can be improved by installing a Solid State Disk (SSD), adding more RAM to your system, reducing the number of programs you have open, or upgrading to a newer system architecture (for instance, Ivy Bridge or Haswell). Out of these options, adding more RAM is generally the most effective solution. Explanation The default behavior of Windows is to give active applications priority over inactive applications for having a spot in RAM. When there’s significant memory pressure (meaning the system doesn’t have a lot of free RAM if it were to let every program have all the RAM it wants), it starts putting minimized programs into the page file, which means it writes out their contents from RAM to disk, and then makes that area of RAM free. That free RAM helps programs you’re actively using — say, your web browser — run faster, because if they need to claim a new segment of RAM (like when you open a new tab), they can do so. This “free” RAM is also used as page cache, which means that when active programs attempt to read data on your hard disk, that data might be cached in RAM, which prevents your hard disk from being accessed to get that data. By using the majority of your RAM for page cache, and swapping out unused programs to disk, Windows is trying to improve responsiveness of the program(s) you are actively using, by making RAM available to them, and caching the files they access in RAM instead of the hard disk. The downside of this behavior is that minimized programs can take a while to have their contents copied from the page file, on disk, back into RAM. The time increases the larger the program’s footprint in memory. This is why you experience that delay when maximizing Photoshop. RAM is many times faster than a hard disk (depending on the specific hardware, it can be up to several orders of magnitude). An SSD is considerably faster than a hard disk, but it is still slower than RAM by orders of magnitude. Having your page file on an SSD will help, but it will also wear out the SSD more quickly than usual if your page file is heavily utilized due to RAM pressure. Remedies Here is an explanation of the available remedies, and their general effectiveness: Installing more RAM: This is the recommended path. If your system does not support more RAM than you already have installed, you will need to upgrade more of your system: possibly your motherboard, CPU, chassis, power supply, etc. depending on how old it is. If it’s a laptop, chances are you’ll have to buy an entire new laptop that supports more installed RAM. When you install more RAM, you reduce memory pressure, which reduces use of the page file, which is a good thing all around. You also make available more RAM for page cache, which will make all programs that access the hard disk run faster. As of Q4 2013, my personal recommendation is that you have at least 8 GB of RAM for a desktop or laptop whose purpose is anything more complex than web browsing and email. That means photo editing, video editing/viewing, playing computer games, audio editing or recording, programming / development, etc. all should have at least 8 GB of RAM, if not more. Run fewer programs at a time: This will only work if the programs you are running do not use a lot of memory on their own. Unfortunately, Adobe Creative Suite products such as Photoshop CS6 are known for using an enormous amount of memory. This also limits your multitasking ability. It’s a temporary, free remedy, but it can be an inconvenience to close down your web browser or Word every time you start Photoshop, for instance. This also wouldn’t stop Photoshop from being swapped when minimizing it, so it really isn’t a very effective solution. It only helps in some specific situations. Install an SSD: If your page file is on an SSD, the SSD’s improved speed compared to a hard disk will result in generally improved performance when the page file has to be read from or written to. Be aware that SSDs are not designed to withstand a very frequent and constant random stream of writes; they can only be written over a limited number of times before they start to break down. Heavy use of a page file is not a particularly good workload for an SSD. You should install an SSD in combination with a large amount of RAM if you want maximum performance while preserving the longevity of the SSD. Use a newer system architecture: Depending on the age of your system, you may be using an out of date system architecture. The “system architecture” is generally defined as the “generation” (think generations like children, parents, grandparents, etc.) of the motherboard and CPU. Newer generations generally support faster I/O (input/output), better memory bandwidth, lower latency, and less contention over shared resources, instead providing dedicated links between components. For example, starting with the “Nehalem” generation (around 2009), the Front-Side Bus (FSB) was eliminated, which removed a common bottleneck, because almost all system components had to share the same FSB for transmitting data. This was replaced with a “point to point” architecture, meaning that each component gets its own dedicated “lane” to the CPU, which continues to be improved every few years with new generations. You will generally see a more significant improvement in overall system performance depending on the “gap” between your computer’s architecture and the latest one available. For example, a Pentium 4 architecture from 2004 is going to see a much more significant improvement upgrading to “Haswell” (the latest as of Q4 2013) than a “Sandy Bridge” architecture from ~2010. Links Related questions: How to reduce disk thrashing (paging)? Windows Swap (Page File): Enable or Disable? Also, just in case you’re considering it, you really shouldn’t disable the page file, as this will only make matters worse; see here. And, in case you needed extra convincing to leave the Windows Page File alone, see here and here. Have something to add to the explanation? Sound off in the the comments. Want to read more answers from other tech-savvy Stack Exchange users? Check out the full discussion thread here.     

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  • Why are my hard drives failing?

    - by WishCow
    I have a small Ubuntu server running at home, with 2 HDDs. There are two software raids (raid1) on the disks, managed by mdadm, which I believe is irrelevant, but mentioning it anyway. Both of the HDDs are Western Digital, and have been used for around 2 years, when one of them started making clicking noises, and died. I figured that maybe it's natural after 2 years, so I bought a new one, and resynced the raid arrays. After about a month, the other drive also died. I didn't get suspicious, since both drives have been bought at the same time, it's not that surprising to see both of them near each other, so I bought another one. So far, 2 old drives failed, and 2 brand new in the system. After one month, one of the new drives died. This is when it started getting suspicious. Since the PC was put together from some really old parts (think AthlonXP), I figured that maybe the motherboard's SATA controller is the culprit. Of course you can't switch parts easily in an old PC like this, so I bought a whole system, new MB, new CPU, new RAM. Took the just failed drive back, since it was under warranty, and got it replaced. So it is up to 2 failed drives from the old ones, and 1 failed drive from the new ones. No problems, for 1 month. After that errors were creeping up again in /var/log/messages, and mdadm was reporting raid array failures. I started tearing my hair out. Everything is new in the system, it's up to the third brand new HDD, it's simply not possible that all of the new drives that I bought were faulty. Let's see what is still common... the cables. Okay, long shot, let's replace the SATA cables. Take HDD back, smile to the guy at the counter and say that I'm really unlucky. He replaces the HDD. I come home, one month passes and one of HDDs fails, again. I'm not joking. Two of the brand new HDDs have failed. Maybe it's a bug in the OS. Let's see what the manufacturer's testing tool says. Download testing tool, burn it to a CD, reboot, leave HDD testing overnight. Test says that the drive is faulty, and I should back up everything, if I still can. I don't know what's happening, but it does not look like a software problem, something is definitely thrashing the HDDs. I should mention now, that the whole system is in a shoebox. Since there are a load of "build your own ikea case" stuff, I thought there shouldn't be any problems throwing the thing in a box, and stuffing it away somewhere. The box is well ventilated, but I thought that just maybe the drives were overheating. There is no other possible answer to this. So I took the HDD back, and got it replaced (for the 3rd time), and bought HDD coolers. And just now, I have heard the sound of doom. click click whizzzzzzzzz. SSH into the box: You have new mail! mail r 1 DegradedArrayEvent on /dev/md0 ... dmesg output: [47128.000051] ata3: lost interrupt (Status 0x50) [47128.000097] end_request: I/O error, dev sda, sector 58588863 [47128.000134] md: super_written gets error=-5, uptodate=0 [48043.976054] ata3: lost interrupt (Status 0x50) [48043.976086] ata3.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x6 frozen [48043.976132] ata3.00: cmd c8/00:18:bf:40:52/00:00:00:00:00/e1 tag 0 dma 12288 in [48043.976135] res 40/00:00:00:4f:c2/00:00:00:00:00/00 Emask 0x4 (timeout) [48043.976208] ata3.00: status: { DRDY } [48043.976241] ata3: soft resetting link [48044.148446] ata3.00: configured for UDMA/133 [48044.148457] ata3.00: device reported invalid CHS sector 0 [48044.148477] ata3: EH complete Recap: No possibility of overheating 6 drives have failed, 4 of those have been brand new. I'm not sure now that the original two have been faulty, or suffered the same thing that the new ones. There is nothing common in the system, apart from the OS which is Ubuntu Karmic now (started with Jaunty). New MB, new CPU, new RAM, new SATA cables. No, the little holes on the HDD are not covered I'm crying. Really. I don't have the face to return to the store now, it's not possible for 4 drives to fail under 4 months. A few ideas that I have been thinking: Is it possible that I fuck up something when I partition and resync the drives? Can it be so bad that it physicaly wrecks the drive? (since the vendor supplied tool says that the drive is damaged) I do the partitoning with fdisk, and use the same block size for the raid1 partitions (I check the exact block sizes with fdisk -lu) Is it possible that the linux kernel or mdadm, or something is not compatible with this exact brand of HDDs, and thrashes them? Is it possible that it may be the shoebox? Try placing it somewhere else? It's under a shelf now, so humidity is not a problem either. Is it possible that a normal PC case will solve my problem (I'm going to shoot myself then)? I will get a picture tomorrow. Am I just simply cursed? Any help or speculation is greatly appreciated. Edit: The power strip is guarded against overvoltage. Edit2: I have moved inbetween these 4 months, so the possibility of the cause being "dirty" electricity in both places, is very low. Edit3: I have checked the voltages in the BIOS (couldn't borrow a multimeter), and they are all seem correct, the biggest discrepancy is in the 12V, because it's supplying 11.3. Should I be worried about that? Edit4: I put my desktop PC's PSU into the server. The BIOS reported much more accurate voltage readings, and also it has successfully rebuilt the raid1 array, which took some 3-4 hours, so I feel a little positive now. Will get a new PSU tomorrow to test with that. Also, attaching the picture about the box: (disregard the 3rd drive)

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  • MySQL Config File for Large System

    - by Jonathon
    We are running MySQL on a Windows 2003 Server Enterpise Edition box. MySQL is about the only program running on the box. We have approx. 8 slaves replicated to it, but my understanding is that having multiple slaves connecting to the same master does not significantly slow down performance, if at all. The master server has 16G RAM, 10 Terabyte drives in RAID 10, and four dual-core processors. From what I have seen from other sites, we have a really robust machine as our master db server. We just upgraded from a machine with only 4G RAM, but with similar hard drives, RAID, etc. It also ran Apache on it, so it was our db server and our application server. It was getting a little slow, so we split the db server onto this new machine and kept the application server on the first machine. We also distributed the application load amongst a few of our other slave servers, which also run the application. The problem is the new db server has mysqld.exe consuming 95-100% of CPU almost all the time and is really causing the app to run slowly. I know we have several queries and table structures that could be better optimized, but since they worked okay on the older, smaller server, I assume that our my.ini (MySQL config) file is not properly configured. Most of what I see on the net is for setting config files on small machines, so can anyone help me get the my.ini file correct for a large dedicated machine like ours? I just don't see how mysqld could get so bogged down! FYI: We have about 100 queries per second. We only use MyISAM tables, so skip-innodb is set in the ini file. And yes, I know it is reading the ini file correctly because I can change some settings (like the server-id and it will kill the server at startup). Here is the my.ini file: #MySQL Server Instance Configuration File # ---------------------------------------------------------------------- # Generated by the MySQL Server Instance Configuration Wizard # # # Installation Instructions # ---------------------------------------------------------------------- # # On Linux you can copy this file to /etc/my.cnf to set global options, # mysql-data-dir/my.cnf to set server-specific options # (@localstatedir@ for this installation) or to # ~/.my.cnf to set user-specific options. # # On Windows you should keep this file in the installation directory # of your server (e.g. C:\Program Files\MySQL\MySQL Server X.Y). To # make sure the server reads the config file use the startup option # "--defaults-file". # # To run run the server from the command line, execute this in a # command line shell, e.g. # mysqld --defaults-file="C:\Program Files\MySQL\MySQL Server X.Y\my.ini" # # To install the server as a Windows service manually, execute this in a # command line shell, e.g. # mysqld --install MySQLXY --defaults-file="C:\Program Files\MySQL\MySQL Server X.Y\my.ini" # # And then execute this in a command line shell to start the server, e.g. # net start MySQLXY # # # Guildlines for editing this file # ---------------------------------------------------------------------- # # In this file, you can use all long options that the program supports. # If you want to know the options a program supports, start the program # with the "--help" option. # # More detailed information about the individual options can also be # found in the manual. # # # CLIENT SECTION # ---------------------------------------------------------------------- # # The following options will be read by MySQL client applications. # Note that only client applications shipped by MySQL are guaranteed # to read this section. If you want your own MySQL client program to # honor these values, you need to specify it as an option during the # MySQL client library initialization. # [client] port=3306 [mysql] default-character-set=latin1 # SERVER SECTION # ---------------------------------------------------------------------- # # The following options will be read by the MySQL Server. Make sure that # you have installed the server correctly (see above) so it reads this # file. # [mysqld] # The TCP/IP Port the MySQL Server will listen on port=3306 #Path to installation directory. All paths are usually resolved relative to this. basedir="D:/MySQL/" #Path to the database root datadir="D:/MySQL/data" # The default character set that will be used when a new schema or table is # created and no character set is defined default-character-set=latin1 # The default storage engine that will be used when create new tables when default-storage-engine=MYISAM # Set the SQL mode to strict #sql-mode="STRICT_TRANS_TABLES,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION" # we changed this because there are a couple of queries that can get blocked otherwise sql-mode="" #performance configs skip-locking max_allowed_packet = 1M table_open_cache = 512 # The maximum amount of concurrent sessions the MySQL server will # allow. One of these connections will be reserved for a user with # SUPER privileges to allow the administrator to login even if the # connection limit has been reached. max_connections=1510 # Query cache is used to cache SELECT results and later return them # without actual executing the same query once again. Having the query # cache enabled may result in significant speed improvements, if your # have a lot of identical queries and rarely changing tables. See the # "Qcache_lowmem_prunes" status variable to check if the current value # is high enough for your load. # Note: In case your tables change very often or if your queries are # textually different every time, the query cache may result in a # slowdown instead of a performance improvement. query_cache_size=168M # The number of open tables for all threads. Increasing this value # increases the number of file descriptors that mysqld requires. # Therefore you have to make sure to set the amount of open files # allowed to at least 4096 in the variable "open-files-limit" in # section [mysqld_safe] table_cache=3020 # Maximum size for internal (in-memory) temporary tables. If a table # grows larger than this value, it is automatically converted to disk # based table This limitation is for a single table. There can be many # of them. tmp_table_size=30M # How many threads we should keep in a cache for reuse. When a client # disconnects, the client's threads are put in the cache if there aren't # more than thread_cache_size threads from before. This greatly reduces # the amount of thread creations needed if you have a lot of new # connections. (Normally this doesn't give a notable performance # improvement if you have a good thread implementation.) thread_cache_size=64 #*** MyISAM Specific options # The maximum size of the temporary file MySQL is allowed to use while # recreating the index (during REPAIR, ALTER TABLE or LOAD DATA INFILE. # If the file-size would be bigger than this, the index will be created # through the key cache (which is slower). myisam_max_sort_file_size=100G # If the temporary file used for fast index creation would be bigger # than using the key cache by the amount specified here, then prefer the # key cache method. This is mainly used to force long character keys in # large tables to use the slower key cache method to create the index. myisam_sort_buffer_size=64M # Size of the Key Buffer, used to cache index blocks for MyISAM tables. # Do not set it larger than 30% of your available memory, as some memory # is also required by the OS to cache rows. Even if you're not using # MyISAM tables, you should still set it to 8-64M as it will also be # used for internal temporary disk tables. key_buffer_size=3072M # Size of the buffer used for doing full table scans of MyISAM tables. # Allocated per thread, if a full scan is needed. read_buffer_size=2M read_rnd_buffer_size=8M # This buffer is allocated when MySQL needs to rebuild the index in # REPAIR, OPTIMZE, ALTER table statements as well as in LOAD DATA INFILE # into an empty table. It is allocated per thread so be careful with # large settings. sort_buffer_size=2M #*** INNODB Specific options *** innodb_data_home_dir="D:/MySQL InnoDB Datafiles/" # Use this option if you have a MySQL server with InnoDB support enabled # but you do not plan to use it. This will save memory and disk space # and speed up some things. skip-innodb # Additional memory pool that is used by InnoDB to store metadata # information. If InnoDB requires more memory for this purpose it will # start to allocate it from the OS. As this is fast enough on most # recent operating systems, you normally do not need to change this # value. SHOW INNODB STATUS will display the current amount used. innodb_additional_mem_pool_size=11M # If set to 1, InnoDB will flush (fsync) the transaction logs to the # disk at each commit, which offers full ACID behavior. If you are # willing to compromise this safety, and you are running small # transactions, you may set this to 0 or 2 to reduce disk I/O to the # logs. Value 0 means that the log is only written to the log file and # the log file flushed to disk approximately once per second. Value 2 # means the log is written to the log file at each commit, but the log # file is only flushed to disk approximately once per second. innodb_flush_log_at_trx_commit=1 # The size of the buffer InnoDB uses for buffering log data. As soon as # it is full, InnoDB will have to flush it to disk. As it is flushed # once per second anyway, it does not make sense to have it very large # (even with long transactions). innodb_log_buffer_size=6M # InnoDB, unlike MyISAM, uses a buffer pool to cache both indexes and # row data. The bigger you set this the less disk I/O is needed to # access data in tables. On a dedicated database server you may set this # parameter up to 80% of the machine physical memory size. Do not set it # too large, though, because competition of the physical memory may # cause paging in the operating system. Note that on 32bit systems you # might be limited to 2-3.5G of user level memory per process, so do not # set it too high. innodb_buffer_pool_size=500M # Size of each log file in a log group. You should set the combined size # of log files to about 25%-100% of your buffer pool size to avoid # unneeded buffer pool flush activity on log file overwrite. However, # note that a larger logfile size will increase the time needed for the # recovery process. innodb_log_file_size=100M # Number of threads allowed inside the InnoDB kernel. The optimal value # depends highly on the application, hardware as well as the OS # scheduler properties. A too high value may lead to thread thrashing. innodb_thread_concurrency=10 #replication settings (this is the master) log-bin=log server-id = 1 Thanks for all the help. It is greatly appreciated.

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  • Can ping device from one computer and not the other

    - by Sean Duggan
    I've recently been assigned to work on a diagnostic program done in C++ which communicates with a piece of electronic equipment. Our normal scenario involves communicating via an RS232 interface, but I've been asked to make our program work over ethernet, source code having been done in Visual Basic. After much thrashing about trying to get the code to work and continuing to get 10049 Winsock errors when I tried to connect, I tried pinging the switch. From the computer the VB program is running on, I can see the switch via ping, nslookup, tracert, and pathping (I was going down the list of programs) and I can do this via URI or IP address. From my laptop, sending the same commands fails every time. They're both using the same network cable and the same USB-to-Ethernet device (I've been swapping them between tests) but one can see the switch and the other cannot. I'm working on the programming end, but the ping results makes me think that there might be a network issue stymieing me. wry grin I'm not much of a network guy, so I'm appealing to expert assistance. Both computers are running Windows XP if that helps. The connection is to an "IP-RS8" device which then connects to our VCU-C units. Each unit is accessible via URI or IP address on the desktop computer we usually have connected to the units (it's running the older VB program that I was asked to lift the networking code from). The connection is made via a USB-to-Ethernet adapter so as to leave the regular Ethernet port available for connecting to the company network. Hmm... come to think of it, I've probably been confusing the issue, talking about pinging "the switch" rather than indicating that it's the devices. My apologies. Communication is generally done with a DLL that uses Winsock functions to make queries for data from the VCU and then to receive. I'm failing when connecting. I haven't found anything on the firewall which should block these commands, but I'll keep poking. I don't know if it's potentially relevant, but on the desktop, the adapter maps to Local Area Connection 3 while on the laptop, it consistently maps to Local Area Connection 2. Currently reading up on DHCP. IPConfig /all results: Desktop Host Name . . . . . . . . . . . . : AMERDAEXXXXXX Primary Dns Suffix . . . . . . . : amer.example.com Node Type . . . . . . . . . . . . : Hybrid IP Routing Enabled. . . . . . . . : No WINS Proxy Enabled. . . . . . . . : No DNS Suffix Search List. . . . . . : COMPANY.com amer.example.com atle.example.com cone.example.com apac.example.com scan.example.com bYX.example.com Ethernet adapter Local Area Connection X: Connection-specific DNS Suffix . : amer.example.com Description . . . . . . . . . . . : Broadcom NetXtreme XYxx Gigabit Controller Physical Address. . . . . . . . . : YY-XX-YB-XX-XX-XX Dhcp Enabled. . . . . . . . . . . : Yes Autoconfiguration Enabled . . . . : Yes IP Address. . . . . . . . . . . . : XYY.XXX.XY.XXX Subnet Mask . . . . . . . . . . . : XXX.XXX.XXY.Y Default Gateway . . . . . . . . . : XYY.XXX.XY.X DHCP Server . . . . . . . . . . . : XY.XXX.XXY.XX DNS Servers . . . . . . . . . . . : XY.XXX.XXY.XX XY.XXY.XXY.XX Primary WINS Server . . . . . . . : XY.XXX.XXY.X Secondary WINS Server . . . . . . : XY.XXY.XXY.X Lease Obtained. . . . . . . . . . : Thursday, July XX, XYXX XY:XX:XX AM Lease Expires . . . . . . . . . . : Sunday, July XX, XYXX XY:XX:XX AM Ethernet adapter Local Area Connection X: Connection-specific DNS Suffix . : Description . . . . . . . . . . . : ASIX axYYYYX USBX.Y to Fast Ethernet Adapter Physical Address. . . . . . . . . : YY-XY-BY-YX-XY-AY Dhcp Enabled. . . . . . . . . . . : Yes Autoconfiguration Enabled . . . . : Yes IP Address. . . . . . . . . . . . : XY.Y.Y.X Subnet Mask . . . . . . . . . . . : XXX.XXX.XXY.Y Default Gateway . . . . . . . . . : XY.Y.Y.X DHCP Server . . . . . . . . . . . : XY.Y.Y.XY DNS Servers . . . . . . . . . . . : XY.Y.Y.X Lease Obtained. . . . . . . . . . : Thursday, July XX, XYXX XY:XX:XY AM Lease Expires . . . . . . . . . . : Tuesday, August YX, XYXX XX:XY:XY AM Laptop Windows IP Configuration Host Name . . . . . . . . . . . . : AMERLAFYYXXYX Primary Dns Suffix . . . . . . . : amer.example.com Node Type . . . . . . . . . . . . : Hybrid IP Routing Enabled. . . . . . . . : No WINS Proxy Enabled. . . . . . . . : No DNS Suffix Search List. . . . . . : COMPANY.com amer.example.com atle.example.com cone.example.com apac.example.com scan.example.com bYX.example.com Ethernet adapter Local Area Connection: Connection-specific DNS Suffix . : amer.example.com Description . . . . . . . . . . . : Intel(R) 82567LM Gigabit Network Connection Physical Address. . . . . . . . . : YY-XY-BY-DY-XB-YX Dhcp Enabled. . . . . . . . . . . : Yes Autoconfiguration Enabled . . . . : Yes IP Address. . . . . . . . . . . . : XYY.XXX.XY.XY Subnet Mask . . . . . . . . . . . : XXX.XXX.XXY.Y Default Gateway . . . . . . . . . : XYY.XXX.XY.X DHCP Server . . . . . . . . . . . : XY.XXX.XXY.XX DNS Servers . . . . . . . . . . . : XY.XXX.XXY.XX XY.XXY.XXY.XX Primary WINS Server . . . . . . . : XY.XXX.XXY.X Secondary WINS Server . . . . . . : XY.XXY.XXY.X Lease Obtained. . . . . . . . . . : Thursday, July XX, XYXX XX:XX:XX AM Lease Expires . . . . . . . . . . : Sunday, July XX, XYXX XX:XX:XX AM Ethernet adapter {XYXAAYXX-YEDY-XXYX-YYEX-BYXYXXYEEYEX}: Connection-specific DNS Suffix . : Description . . . . . . . . . . . : Nortel IPSECSHM Adapter - Packet Scheduler iniport Physical Address. . . . . . . . . : XX-XX-XX-XX-XX-YY Dhcp Enabled. . . . . . . . . . . : No IP Address. . . . . . . . . . . . : Y.Y.Y.Y Subnet Mask . . . . . . . . . . . : Y.Y.Y.Y Default Gateway . . . . . . . . . : Ethernet adapter Leaf Networks Adapter: Connection-specific DNS Suffix . : Description . . . . . . . . . . . : Leaf Networks Adapter Physical Address. . . . . . . . . : YY-FF-FA-BC-YF-AY Dhcp Enabled. . . . . . . . . . . : No IP Address. . . . . . . . . . . . : X.XYY.XY.XX Subnet Mask . . . . . . . . . . . : XXX.Y.Y.Y Default Gateway . . . . . . . . . : Ethernet adapter Local Area Connection 3: Media State . . . . . . . . . . . : Media disconnected Description . . . . . . . . . . . : Bluetooth LAN Access Server Driver Physical Address. . . . . . . . . : YY-FX-AX-YA-BY-CA Ethernet adapter Wireless Network Connection 2: Media State . . . . . . . . . . . : Media disconnected Description . . . . . . . . . . . : Intel(R) WiFi Link 5300 AGN Physical Address. . . . . . . . . : YY-XX-YA-CX-FC-YE Ethernet adapter Local Area Connection 2: Connection-specific DNS Suffix . : Description . . . . . . . . . . . : ASIX ax88772 USB2.0 to Fast Ethernet Adapter Physical Address. . . . . . . . . : YY-XY-BY-YX-XY-AY Dhcp Enabled. . . . . . . . . . . : No IP Address. . . . . . . . . . . . : XYX.XYY.X.X Subnet Mask . . . . . . . . . . . : XXX.XXX.XXX.Y Default Gateway . . . . . . . . . :

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