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  • Disk fragmentation when dealing with many small files

    - by Zorlack
    On a daily basis we generate about 3.4 Million small jpeg files. We also delete about 3.4 Million 90 day old images. To date, we've dealt with this content by storing the images in a hierarchical manner. The heriarchy is something like this: /Year/Month/Day/Source/ This heirarchy allows us to effectively delete days worth of content across all sources. The files are stored on a Windows 2003 server connected to a 14 disk SATA RAID6. We've started having significant performance issues when writing-to and reading-from the disks. This may be due to the performance of the hardware, but I suspect that disk fragmentation may be a culprit at well. Some people have recommended storing the data in a database, but I've been hesitant to do this. An other thought was to use some sort of container file, like a VHD or something. Does anyone have any advice for mitigating this kind of fragmentation? Additional Info: The average file size is 8-14KB Format information from fsutil: NTFS Volume Serial Number : 0x2ae2ea00e2e9d05d Version : 3.1 Number Sectors : 0x00000001e847ffff Total Clusters : 0x000000003d08ffff Free Clusters : 0x000000001c1a4df0 Total Reserved : 0x0000000000000000 Bytes Per Sector : 512 Bytes Per Cluster : 4096 Bytes Per FileRecord Segment : 1024 Clusters Per FileRecord Segment : 0 Mft Valid Data Length : 0x000000208f020000 Mft Start Lcn : 0x00000000000c0000 Mft2 Start Lcn : 0x000000001e847fff Mft Zone Start : 0x0000000002163b20 Mft Zone End : 0x0000000007ad2000

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  • Reverse Proxy (mod_rewrite) and Rails (absolute paths)

    - by SooDesuNe
    I have front end rails app, that reverse proxies to any of a number of backend rails apps depending on URL, for example http://www.my_host.com/app_one reverse proxies to http://www.remote_host_running_app_one.com such that a URL like http://www.my_host.com/app_one/users will display the contents of http://www.remote_host_running_app_one.com/users I have a large, and ever expanding number of backends, so they can not be explicitly listed anywhere other than a database. This is no problem for mod_rewrite using a prg:/ rewrite map reverse proxy. The question is, the urls returned by rails helpers have the form /controller/action making them absolute to the root. This is a problem for the page served by mod_rewrite because links on the proxied page appear as absolute to the domain. i.e.: http://www.my_host.com/app_one/controller/action has links that end up looking like /controller/action/ when they need to look like /app_one/controller/action mod_proxy_html seems like the right idea, but it doesn't seem to be as dynamic as I would need, since the rules need to be hard coded into the config files. Is there a way to fix this server-side, so that the links will be routed correctly?

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  • Blue screen of Death on Install

    - by Toby Allen
    I have a machine with Windows Vista Installed. It has an Intel X25 SSD as the System Drive I want to reinstall (I plan to format and overwrite Vista) with XP. When I boot up using the Dell XP CD it loads the initial drivers then i get a Blue Screen. This is quite concerning. The installed OS works ok, but its giving problems so I want to remove it. Should I just format the SSD and try again? Will this make any difference? Can I do something to avoid hitting the Blue Screen? Its possible I had corrupt sectors on one of the other disks, will a new XP install use the System drive or drive 0? Can I force the install to use a specific drive when installing? Error: *** STOP: 0x0000007B (0xF78D2524,0x0000034,0x00000000,0x00000000) I never did find the answer, however I removed the SSD and tried to install on other disk - CRASH I disconnected the other disk and tried to install with only SSD plugged in - CRASH I removed 1 block of RAM - CRASH I used a windows 7 CD - NO CRASH

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  • Get OpenVPN clients names to resolve through dnsmasq

    - by Fake Name
    I have a PFSense box running as an OpenVPN server. There are several remote devices that connect through the VPN (as tap devices). The VPN stuff is working, I can access the remote hardware by looking up the IP assigned to each device on the PFSense router. What I'd like is to have it so I can resolve the remote hardware addresses via DNS while on the local network. Note that this is only local-network - remote-device (they're backup boxes). I don't need to have the remote devices resolve using the local DNS forwarding agent. I have the rest of the devices on the network that need to be accessible via DNS report their name during the DHCP process. However, the IP assignment for OpenVPN tap clients, while it is dynamic (which is why I need DNS), does not seem to use the local DHCP server. How can I have my openvpn server add information for it's clients to the dnsmask resolver? Is this setup even reasonable (I'm not familiar with openVPN at all)?

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  • RAIDs with a lot of spindles - how to safely put to use the "wasted" space

    - by kubanczyk
    I have a fairly large number of RAID arrays (server controllers as well as midrange SAN storage) that all suffer from the same problem: barely enough spindles to keep the peak I/O performance, and tons of unused disk space. I guess it's a universal issue since vendors offer the smallest drives of 300 GB capacity but the random I/O performance hasn't really grown much since the time when the smallest drives were 36 GB. One example is a database that has 300 GB and needs random performance of 3200 IOPS, so it gets 16 disks (4800 GB minus 300 GB and we have 4.5 TB wasted space). Another common example are redo logs for a OLTP database that is sensitive in terms of response time. The redo logs get their own 300 GB mirror, but take 30 GB: 270 GB wasted. What I would like to see is a systematic approach for both Linux and Windows environment. How to set up the space so sysadmin team would be reminded about the risk of hindering the performance of the main db/app? Or, even better, to be protected from that risk? The typical situation that comes to my mind is "oh, I have this very large zip file, where do I uncompress it? Umm let's see the df -h and we figure something out in no time..." I don't put emphasis on strictness of the security (sysadmins are trusted to act in good faith), but on overall simplicity of the approach. For Linux, it would be great to have a filesystem customized to cap I/O rate to a very low level - is this possible?

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  • Windows 7 Sharing issue on RAID 5 Array(s)

    - by K.A.I.N
    Greetings all, I'm having a very odd error with a windows 7 ultimate x64 system. The network system setup is as follows: 2x XP Pro 32 Bit machines 1x Vista ultimate x64 machine 2x Windows 7 x64 Ultimate machines all chained into 1x 16 port netgear prosafe gigabit switch, the windows 7 & vista machines are duplexed. Also there is a router (netgear Rangemax) chained off the switch I am basically using one of the windows 7 machines to host storage & stream media to other machines. To this end i have put 2x 3tb hardware RAID 5 arrays in it and assorted other spare disks which i have shared the roots of. The unusual problems start when i am getting Access denied, Please contact administrator for permission blah blah blah when trying to access both of the RAID 5 arrays but not the other stand alones. I have checked the permission settings, i have added everyone to the read permission for the root, i have tried moving things into sub directories then sharing them. I have tried various setting combinations in HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa and always the same. I have tried flushing caches all round, disabling and re-enabling shares & sharing after restart as well as several other things & the result is always the same... No problem on individual drives but access denied on both the RAID arrays from both XP & Vista & Windows 7 machines. One interesting quirk that may lead to an answer is that there is no "offline status" information regarding the folders when you select the RAID 5s from a windows 7 machine yet there is on the normal drives which say they are online. It is as if the raid is present but turned off or spun down but as far as i was aware windows will spin an array back up on network request and on the machine itself the drives seem to be online and can be accessed. Have to admit this has me stumped. Any suggestions anyone? Thanks in advance for any fellow geek assistance. K.A.I.N

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  • How do I fully share a Hard Drive on my Local Network?

    - by GingerLee
    I have 4 computers connected to a router (DD-WRT) My main PC is Windows 7 (Home Premium). This machine has 2 Hard Disks: HD1 is used for my OS and the other (HD2) is used to store files. My 3 other machines are 1. Ubuntu Destop that I use to learn about linux, 2. A Mac OSX laptop, and 3. A netbook running windows 7. How do I easily share HD2 with my other machines? I would like all my machines to have full access & permissions to HD2 however I would like to RESTRICT access to only PCs that are connected to my router (either via LAN and WiFi) --- btw, I know this is not very secure due to WiFi vulnerability , however, I currently MAC address restrict WiFi connections my router. Extra Info: I have already tried to use the Windows Folder Sharing feature: i.e. I right click over the icon of HD2, and click on the Sharing Tab, but in sub-window labeled "Network File and Folder Sharing", the "Share" button is grayed out. I can click on "Advanced Shared" but that just takes me to a screen in which I have to set certain permissions. What is not clear to me is: How do I set a criteria that shares HD2 with all computer connected to my router?

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  • Performance-optimizing Oracle 10g on a server that is also a Tomcat JSP app server?

    - by PKHunter
    I have inherited a simple RedHat 5 - 64bit platform. It has SCSI disks on RAID1, with 16GB of RAM. Double Core CPU. Oracle 10g, Release 2. This would be a decent platform for running the DB only, perhaps, but the same server in an "A-A mode" clustering (very simple) also runs Tomcat and there are several Java servlets running on this. Sadly there is no caching platform etc. We only use an external CDN for some html caching. I am personally more familiar with web environments on the LAMPP platform (apache, php, mysql, postgresql). PROBLEM: Because the server has both Tomcat JSP/Java and Oracle 10g running on the same server, with no caching, I have some issues of the server going down. Often, sadly. QUESTION: What are my options in terms of improving performance of all these different apps? Connection Pooling? Example, in Postgresql world we have PgBouncer, which really helps things. Does Oracle have something similar? Or is there a famous Java-based external pooler that people use in production environments? (I'm not familiar with Java) Any "SQL cache" as in the MySQL and Postgresql world? Any other kind of application cache, as "APC" or "eAccelarator" in the PHP world? The "OSCache" stuff from the Java world (JSP thingie I found on Google: http://onjava.com/pub/a/onjava/2005/01/05/jspcache.html?page=2) ... What else? Sorry if this is a noob question. I have googled and googled, but problem is I don't know what to google for, other than the broad general concepts above. So if not full answers, I would even appreciate basic pointers and I am happy to JFGI myself. Thanks!

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  • How can I increase the size of the hard disk used by my Virtual Machine Manager (VMM) vm?

    - by Scott Langham
    In Virtual Machine Manager admin console, I used the 'New virtual machine' wizard and created a machine from an existing template. When I got to the Configure Hardware step, I selected the primary hard disk (which is a dynamic) disk and tried to increase it's maximum size, but this control is disabled so I can't increase it. It's not big enough for my purposes. how do I increase the maximum size of the hard-disk? Thanks. Edit: I am able to add a second hard disk of a size I specify. That's not useful though as I'm trying to install some software, some of which insists on being on drive C.

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  • file read performance degrades as number of files increases

    - by bfallik-bamboom
    We're observing poor file read IO results that we'd like to better understand. We can use fio to write 100 files with a sustained aggregate throughput of ~700MB/s. When we switch the test to read instead of write, the aggregate throughput is only ~55MB/s. The drop seems related to the number of files since the throughput for read and write are comparable for a single file then diverge proportionally as we increase the number of files. The test server has 24 CPU cores, 48GB of memory, and is running CentOS 6.0. The disk hardware is a RAID 6 array with 12 disks and a Dell H800 controller. This device is partitioned with ext4 using the default settings. Increasing the readahead (using blockdev) improves the read throughput significantly but it still doesn't match write speed. For instance, increasing the readahead from 128KB to 1M improved the read throughput to ~145MB/s. Is this a known performance issue in our OS/disk/filesystem configuration? If so, how can we tell? If not, what tools or tests can we use to further isolate the issue? Thanks.

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  • How to improve network performance between two Win 2008 KMV guest having virtio driver already?

    - by taazaa
    I have two physical servers with Ubuntu 10.04 server on them. They are connected with a 1Gbps card over a gigabit switch. Each of these host servers has one Win 2008 guest VM. Both VMs are well provisioned (4 cores, 12GB RAM), RAW disks. My asp.net/sql server applications are running much slower compared to very similar physical setups. Both machines are setup to use virtio for disk and network. I used iperf to check network performance and I get: Physical host 1 ----- Physical Host 2: 957 Mbits/sec Physical host 1 ----- Win 08 Guest 1: 557 Mbits/sec Win 08 Guest 1 ----- Phy host 1: 182 Mbits/sec Win 08 Guest 1 ----- Win 08 Guest 2: 111 Mbits /sec My app is running on Win08 Guest 1 and Guest 2 (web and db). There is a huge drop in network throughput (almost 90%) between the two guest. Further the throughput does not seem to be symmetric between host and guest as well. The CPU utilization on the guests and hosts is less than 2% right now (we are just testing right now). Apart from this, there have been random slow downs in the network to as low as 1 Mbits/sec making the whole application unusable. Any help to trouble shoot this would be appreciated.

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  • Is there a way to use VirtualBox without using it's resource registry?

    - by Catskul
    Summary VirtualBox seems to want everything to be "registered" which makes it much more annoying to work with on the command line. I'm attempting to create an automated script which will create, move, start, stop, and destroy virtual machines and virtual disks. Requiring registration will complicate the task for the following reasons. leaves state information around that can cause unpredicted edgecases causing scripts to fail. creates potential name space collisions for multiple process creating VMs with the same name moving/copying resources on the same machine is more complicated because references in the registry need to be updated copying resources (disk + vm combination) to another machine require reconfiguration once they reach their target machine, and require the transfer of extra meta data to do the reconfiguration. If something unexpectedly fails, and an unregister thus fails to happen, left over configuration information can cause problems in subsequent runs. Use Case My specific use case is for a continuous integration server which creates and destroys VMs and Disk images potentially with the same name, and would require more logic to deal with the registry's statefulness. Imaginary Example It seems that I should just be able to for example (using some imaginary and/or incorrect commands): mkdir foobar customdiskimg_script ./foo/foo.vdi vboxmanage createvm --name "foo" --ostype Linux --basefolder ./foo/foo.xml vboxmanage storagectl ./foo/foo.xml --name foo --add ide vboxmanage storageattach --storagectl foo --medium ./foo/foo.vdi ./foo/foo.xml vboxmanage startvm ./foo/foo.xml TLDR Is there a way to use virtualbox without "registering" harddisks and VMs?

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  • How does the performance of pure Nginx compare to cpNginx?

    - by jb510
    There is now a Cpanel plugin to fairly easily setup Nginx as a reverse proxy on a Cpanel/Apache server. I've been simultaneously interested in setting up my first unmanaged VPS and my first Nginx server and as a masochist figured why not combine the two. I'm wondering however if it's worth setting up a pure Nginx server vs trying out cpNginx on Apache? My goal is solely to host WordPress sites and while what I've read raves about Nginx's is exceptional ability serving static at least as a reverse proxy, I am unclear if there is substantial benefit to running a pure nginx with eAccelorator over cpNginx on Apache for dynamic sites? Regardless I'll be running W3TC on all sites to cache content, but am still interested if there are big CPU reductions running PHP scripts under pure Nginx over cpNginx?

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  • Configure Virtualbox guest with static IP, SSH and internet access from host

    - by koskoz
    I have an Ubuntu Server 12 virtualbox guest running on a Windows 7 host which has a dynamic IP (and I don't wanna change this considering it's a laptop and I'm changing network frenquently). I want to have a static IP for my VM and a SSH access from my host but I still want to have the internet access on my VM. I tried added a second host only adapter and configured /etc/network/interface to set eth1 to a static ip, but I can't connect via SSH to it. Setting only adapter1 to host only works for SSH and static IP but I lose the internet access.

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  • Identifying Exchange 2010 regular process that is walking the mailbox database

    - by toongeneral
    I have an Exchange 2010 server running on a SAN-backed platform. The platform does block-level backups based on a snapshot/incremental basis, that only capture changed data. I was surprised to see a regular period of time where the data changes were happening at a high, sustained rate. Due to the way this system works, that can lead to 1.2TB of stored data per month. The regularity implied a scheduled task, but it is not a fixed interval. It is approximately every 26-32hrs. The disks were performing read operations of ~5MB/s and write operations of ~4.5MB/s, for a period of 3-4hrs. The total written data was ~55-60GB. Reading on TechNet, I am wondering if the following is causing this: http://blogs.technet.com/b/exchange/archive/2011/12/14/database-maintenance-in-exchange-2010.aspx#checksumming The somewhat restrictive thing is that the process only happens at most once every 24 hours. I was able to investigate while it was running, finding the following: the process is store.exe it is working on the mailbox database files while running, it is generating .log files (in the mailbox database folder) consistent with database changes the mailbox database is ~60GB in size, which fits with the total data changes on each iteration I have currently switched to a fixed maintenance window, as a test. It's not clear whether this is the cause, as the symptoms fit, but are not conclusive. Does anyone have any suggestions for additional troubleshooting?

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  • Expand a volume residing on one X-RAID disk installed on a Netgear ReadyNas Duo v2

    - by Sid
    I've got a Netgear ReadyNas Duo v2 (2 disk slots). System is configured with X-RAID which does not provide flexibility but automatically expands based on a sort of RAID-5 logic. I had 2 500 GB hard disk installed, redundant, so I had 500 GB of volume size. I wanted to upgrade the whole system to 3 GB * 2 hard disk maintaining both the data already on the NAS and the data on one of the two 3 TB hard disks. So I did this: Unplugged one disk from the ReadyNas. Now the readynas has 1*500 GB non redundant. Plugged one empty 3 TB hard disk. Now the readynas has 1*500 GB + 1*3 TB, redundant. I waited for the resync. I then unplugged the 500 GB hard disk, so that I have only the 3 TB hard disk with the previous data. Now what I want is to copy the data on my other 3 TB hard disk in the NAS, so that I can plug this other disk in the NAS and use it for redundancy. The problem is that: the NAS has the (single) 3 TB hard disk in X-RAID, but the volume does not expand to 3 TB, it remains fixed to 500 GB. Is there a way to tell the ReadyNas to force expanding the volume to the whole disk without plugging in another hard disk of the same size?

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  • How to suspend and resume browser tab groups?

    - by Robin Green
    Modern browsers such as Firefox and Chrome are able to shutdown and restore the same group of tabs they had before the next time you open them, and even sometimes remember additional tab state such as scroll position within the tab. I would like ideally to be able to select a group of tabs (about some coherent theme, perhaps) and save them away into some kind of "folder" that I could later open independently, without opening any other tabs. Obviously I can use bookmarks for this, but bookmarks are kind of old-fashioned. It would be excellent if it could also record forms that I had filled in but not submitted, scroll position, tab position within the tab group, and any other "dynamic" aspects of the current tab state.

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  • Turn on PC power remotely through the Internet?

    - by W.N.
    I use SVN for my work at home and office, but I usually forget to commit the changes before shutdown. Therefore, I wish I could turn on my home/office PC at office/home. I already have TeamViewer installed on both PCs, so it will be okay as soon as the power is turned on. I have read many articles about this, I found both my PC and office computers support Wake-on-LAN. However, I don't know much about other config. And I need to turn on my computers through the Internet, not on LAN. My office Internet connection has static IP, however, my home Internet connection has dynamic IP, it changes as soon as I reset the modem, but it is not a big problem, I rarely turn the Internet modem off. And I don't have privilege to config office Internet connection, but I have Administration privilege on both PCs. Please give me details steps to turn on my office PC from home, and turn on my home PC from office.

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  • How to set up Nginx as a caching reverse proxy?

    - by Continuation
    I heard recently that Nginx has added caching to its reverse proxy feature. I looked around but couldn't find much info about it. I want to set up Nginx as a caching reverse proxy in front of Apache/Django: to have Nginx proxy requests for some (but not all) dynamic pages to Apache, then cache the generated pages and serve subsequent requests for those pages from cache. Ideally I'd want to invalidate cache in 2 ways: Set an expiration date on the cached item To explicitly invalidate the cached item. E.g. if my Django backend has updated certain data, I'd want to tell Nginx to invalidate the cache of the affected pages Is it possible to set Nginx to do that? How?

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  • Failed Software RAID0 on Linux - Attempting to recover data

    - by Gizmo_the_Great
    I have a two disk RAID0 software raid (not hardware raid) that is reported to have failed during boot and my OS won't start. Using a Live CD, I get the following output : sudo mdadm -E /dev/sdc1 /dev/sdd1 /dev/sdc1: Magic : a92b4efc Version : 1.2 Feature Map : 0x0 Array UUID : 3710713d:fb301031:84b61247:d1d53e0f Name : HP-xw9300:0 Creation Time : Sun Sep 1 15:22:26 2013 Raid Level : -unknown- Raid Devices : 0 Avail Dev Size : 1465145328 (698.64 GiB 750.15 GB) Data Offset : 16 sectors Super Offset : 8 sectors State : active Device UUID : ad427cd2:9f885f57:7f41015f:90f8f6af Update Time : Sun Jun 8 12:35:11 2014 Checksum : a37407ff - correct Events : 1 Device Role : spare Array State : ('A' == active, '.' == missing) /dev/sdd1: Magic : a92b4efc Version : 1.2 Feature Map : 0x0 Array UUID : 3710713d:fb301031:84b61247:d1d53e0f Name : HP-xw9300:0 Creation Time : Sun Sep 1 15:22:26 2013 Raid Level : -unknown- Raid Devices : 0 Avail Dev Size : 976771056 (465.76 GiB 500.11 GB) Data Offset : 16 sectors Super Offset : 8 sectors State : active Device UUID : 2ea0199d:cb08d9e7:0830448a:a1e1e348 Update Time : Sun Jun 8 13:06:19 2014 Checksum : 8883c492 - correct Events : 1 Device Role : spare Array State : ('A' == active, '.' == missing) GParted lists both disks, detects the flags as 'Raid' and lists the data usage. Can anyone please help me re-assemble just so that I can copy some of the data off that I have not backed up recently? Thanks

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  • php5-suhosin Broken Installation

    - by h00j
    Hi i get the following error when trying to install, have you any idea how to fix? apt-get install php5-suhosin Reading package lists... Done Building dependency tree Reading state information... Done Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation: The following packages have unmet dependencies: php5-suhosin : Depends: phpapi-20090626 E: Unable to correct problems, you have held broken packages. I get the following error in my apache2 error log [Mon May 07 21:43:15 2012] [error] [client ip] PHP Warning: PHP Startup: Unable to load dynamic library '/usr/lib/php5/20100525/suhosin.so' - /usr/lib/php5/20100525/suhosin.so: cannot open shared object file: No such file or directory in Unknown on line 0

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  • VPN between Cisco ASA 5505 AND Sonicwall SOHO3

    - by user41451
    Hello. I am trying to establish a site-to-site VPN tunnel between an old SOHO3 and an ASA 5505. The ASA has a static IP and the SOHO3 is dynamic. I have tried everything my limited knowledge lets me and need some advice on how to proceed! Phase 1 (according to the ASA logs) completes - followed by a message saying "All IPSec SA proposals found unacceptable!" so I guess the settings between the two don't match. I have played with various combinations and nothing seems to work - I am overlooking something, just not sure what it is! Any help would be appreciated.

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  • How to "open" existing VMs in Hyper-V without importing them?

    - by Borek
    I had a PC with two physical disks: C: containing the host operating system D: containing a folder D:\VMs where all my virtual machines were stored Now, the C: disk died. I bought a new one, reinstalled Windows on it, enabled Hyper-V feature and now I just need to open the VMs from the D:\VMs folder. However, I don't seem to be able to find a menu item or anything that would allow me to do that - the only thing I see is the "import" command which unfortunately requires the VMs to be explicitly exported (my machines weren't). I firmly believe that when I have all the files constituting a VM (the VHD file, some XML files describing the settings etc.) it must be somehow possible to just "open" these existing VMs in Hyper-V, right? What command am I missing? Edit: I know I can create a blank virtual machines and then just point them to use existing VHDs. However, I am not sure about all the different settings I've made to those VMs so I hope there's a way to simply open those existing VMs instead of recreating them.

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  • How setup federated SQL data to display limited information to a Web server in the DMZ?

    - by Pcav
    I have a SQL server behind a firewall. I need to push some limited SQL 2005 information to a Web Server in the DMZ so that I do not have to let database queries come all the way into the database server on our internal network. I want to push a small amount of dynamic data to a Web server in the DMZ and lock it down so that our hosted website does not need to come into the internal network for information; I want to put a server in the DMZ that will be the only connection allowed to the SQL database. This DMZ server will be the only server that can have any sort of connection to the back-end database so the hosting provider just pull the data from our server in the DMZ...

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  • How to call virtual function of an object in C++

    - by SoonDead
    I'm struggling with calling a virtual function in C++. I'm not experienced in C++, I mainly use C# and Java so I might have some delusions, but bear with me. I have to write a program where I have to avoid dynamic memory allocation if possible. I have made a class called List: template <class T> class List { public: T items[maxListLength]; int length; List() { length = 0; } T get(int i) const { if (i >= 0 && i < length) { return items[i]; } else { throw "Out of range!"; } }; // set the value of an already existing element void set(int i, T p) { if (i >= 0 && i < length) { items[i] = p; } else { throw "Out of range!"; } } // returns the index of the element int add(T p) { if (length >= maxListLength) { throw "Too many points!"; } items[length] = p; return length++; } // removes and returns the last element; T pop() { if (length > 0) { return items[--length]; } else { throw "There is no element to remove!"; } } }; It just makes an array of the given type, and manages the length of it. There is no need for dynamic memory allocation, I can just write: List<Object> objects; MyObject obj; objects.add(obj); MyObject inherits form Object. Object has a virtual function which is supposed to be overridden in MyObject: struct Object { virtual float method(const Input& input) { return 0.0f; } }; struct MyObject: public Object { virtual float method(const Input& input) { return 1.0f; } }; I get the elements as: objects.get(0).method(asdf); The problem is that even though the first element is a MyObject, the Object's method function is called. I'm guessing there is something wrong with storing the object in an array of Objects without dynamically allocating memory for the MyObject, but I'm not sure. Is there a way to call MyObject's method function? How? It's supposed to be a heterogeneous collection btw, so that's why the inheritance is there in the first place. If there is no way to call the MyObject's method function, then how should I make my list in the first place?

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