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  • How to achieve the following RTO & RPO with logshipping only using SQL Server?

    - by Jimmy Chandra
    Trying to come up with viable backup restore & logshipping solution for achieving the following: 15 minutes Recovery Point Objective (no more than 15 minutes data loss at any time) 5 minutes Recovery Time Objective (must be able to get the db up and running back by 5 minutes) Considering using logshipping only (which I think is kind of pushing it, but I want to know if anyone else know how to achieve this). Some other info for consideration: Using 40 Gbit / sec fiber channel between the primary and disaster recovery (DRC) sites The sites are about 600 km apart. At close of business, the amount of data generated is predicted to be about 150 MB/sec. Log backup is planned for every 5 min. Doing some rough calculation I came up w/ the following numbers: 40 Gbit / sec = 5 MB / sec @ 100% network efficiency. 5 MB / sec = 300 MB / min. @ 300 MB / min, the total amount of data that can be transfer considering the 5min RTO is about 1.5GB, but that will left no time for the actual backup and restore, so if we cut it down to 3min logshipping time, which equals to ~900 MB over 3 minutes at 100% network efficiency, that will left about 1 min backup time and 1 minute restore time. Currently don't have any information if the system being used is capable of restoring 900 MB in 1 min, but assume it can. for COB scenario... 150 MB/sec, and considering the 3 min logshipping time, which should equal to about 27 GB of data over 3 mins...??? I think this is where the SLA will break... since there is no way to transfer 27 GB of data over a 40Gbit/sec line in 3 min. Can I get someone else opinion? I am thinking database mirroring might be a better answer for this...

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  • apache with php fastcgi keeps going down

    - by Josh Nankin
    I have an apache2 server configured with MPM worker and php fast cgi. Lately the apache logs have been telling me that MaxClients is being reached frequently, even though it's already pretty high. My server is now constantly going down, and I see a bunch of lines like this in the log: [Sun Mar 06 04:25:40 2011] [error] [client 50.16.83.115] FastCGI: comm with (dynamic) server "/var/local/fcgi/php-cgi-wrapper.fcgi" aborted: (first read) idle timeout (20 sec) [Sun Mar 06 04:25:40 2011] [error] [client 50.16.83.115] FastCGI: incomplete headers (0 bytes) received from server "/var/local/fcgi/php-cgi-wrapper.fcgi" I can see that my php-cgi processes are pretty large (about 70mb on average). Here's my apache configuration for MPM worker: KeepAlive ON KeepAliveTimeout 2 <IfModule mpm_worker_module> StartServers 5 MinSpareThreads 10 MaxSpareThreads 10 ThreadLimit 64 ThreadsPerChild 10 MaxClients 20 MaxRequestsPerChild 2000 </IfModule> Heres my fastcgi apache configuration: <IfModule mod_fastcgi.c> # One shared PHP-managed fastcgi for all sites Alias /fcgi /var/local/fcgi # IMPORTANT: without this we get more than one instance # of our wrapper, which itself spawns 20 PHP processes, so # that would be Bad (tm) FastCgiConfig -idle-timeout 20 -maxClassProcesses 1 <Directory /var/local/fcgi> # Use the + so we don't clobber other options that # may be needed. You might want FollowSymLinks here Options +ExecCGI </Directory> AddType application/x-httpd-php5 .php AddHandler fastcgi-script .fcgi Action application/x-httpd-php5 /fcgi/php-cgi-wrapper.fcgi </IfModule> Here's my fastcgi wrapper: #!/bin/sh PHPRC="/etc/php5/apache2" export PHPRC PHP_FCGI_CHILDREN=8 export PHP_FCGI_CHILDREN exec /usr/bin/php-cgi Any help would be very very much appreciated!

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  • Sql Server 2005 database lost, How to recover all records. MDF/LDF size is same as it should be

    - by Shantanu Gupta
    Few months back, I installed a sql server 2005 on one of my client machine. I gave him a backup option to take backup timely but he never took any backup. Today he called me that "i m not able to see any record of mine." I visited at my clients system and saw that none of the record was present on the tables. There was not even a single row in any of the tables. Then I checked if he has any backup file which i found to be absent. I asked him the reason what could be the possible cause. He said it might be due to virus. After this I checked the size of mdf and ldf file and found it should be what it is. when i created his server mdf ldf file had 2MB of database now it is 83 MB and 193Mb mdf/ldf respectively. This shows the data is still present in it but it is not being displayed. What could be the possible cause and how can i restore all data back to my tables ?

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  • Why are SMART error rates going down?

    - by Jeff Shattock
    I have a hard drive that's part of a Linux software raid5 array. SMART has reported that its multi_zone_error_rate was 0, then 1, then 3. So I figured I better start backing up more frequently and prepare to replace the drive. Now, today, the multi_zone_error_rate of that very same drive is back down to 1. It seems that 2 errors unhappened while I wasn't looking. I've also seen simliar behaviour by inspecting the syslog on the server. Jun 7 21:01:17 FS1 smartd[25593]: Device: /dev/sdc, SMART Usage Attribute: 7 Seek_Error_Rate changed from 200 to 100 Jun 7 21:01:17 FS1 smartd[25593]: Device: /dev/sde, SMART Usage Attribute: 7 Seek_Error_Rate changed from 200 to 100 Jun 7 21:01:18 FS1 smartd[25593]: Device: /dev/sdg, SMART Usage Attribute: 7 Seek_Error_Rate changed from 200 to 100 Jun 8 02:31:18 FS1 smartd[25593]: Device: /dev/sdg, SMART Usage Attribute: 7 Seek_Error_Rate changed from 100 to 200 Jun 8 03:01:17 FS1 smartd[25593]: Device: /dev/sdc, SMART Usage Attribute: 7 Seek_Error_Rate changed from 100 to 200 Jun 8 03:01:17 FS1 smartd[25593]: Device: /dev/sde, SMART Usage Attribute: 7 Seek_Error_Rate changed from 100 to 200 These are raw values, not the human-useful values that smartctl -a produces, but the behaviour is similar: error rates changing, then undoing the change. None of these are the drive that had the multi_zone weirdness. I haven't seen any problems from the RAID; its most recent scrub ( < 24 hours ago) came back totally clean. The only thing I can think of is that the SMART reporting circuitry on the drive isn't working properly all the time. The cables are in tight on the drive and board. What's going on here?

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  • Diagnosing Microsoft SQL Server error 9001: The log for the database is not available.

    - by Scott Mitchell
    Over the weekend a website I run stopped functioning, recording the following error in the Event Viewer each time a request is made to the website: Event ID: 9001 The log for database 'database name' is not available. Check the event log for related error messages. Resolve any errors and restart the database. The website is hosted on a dedicated server, so I am able to RDP into the server and poke around. The LDF file for the database exists in the C:\Program Files\Microsoft SQL Server\MSSQL10.MSSQLSERVER\MSSQL\DATA folder, but attempting to do any work with the database from Management Studio results in a dialog box reporting the same error - 9001: The log for database is not available... This is the first time I've received this error, and I've been hosting this site (and others) on this dedicated web server for over two years now. It is my understanding that this error indicates a corrupt log file. I was able to get the website back online by Detaching the database and then restoring a backup from a couple days ago, but my concern is that this error is indicative of a more sinister problem, namely a hard drive failure. I emailed support at the web hosting company and this was their reply: There doesn't appear to be any other indications of the cause in the Event Log, so it's possible that the log was corrupted. Currently the memory's resources is at 87%, which also may have an impact but is unlikely. Can the log just "become corrupted?" My question: What are the next steps I should take to diagnose this problem? How can I determine if this is, indeed, a hardware problem? And if it is, are there any options beyond replacing the disk? Thanks

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  • Tracking down the cause of a web service fault running in IIS

    - by BG100
    I have built a web service in Visual Studio 2008, and deployed it on IIS 7 running on Windows Server 2008 R2. It has been extensively tested, handles all errors gracefully and logs any uncaught errors to a file using log4net. The system normally runs perfectly, but occasionally (2 or 3 times a day) a fault occurs and screws up the application which needs an iisreset to get it working again. When the fault occurs I get some random errors that are caught by my catch-all error log, such as: Value cannot be null. Could not convert from type 'System.Boolean' to type 'System.DateTime'. Sequence contains no elements These errors are raised on every request until I manually do an iisreset, but there is no sight of them when the system is running normally. The web service is a stateless request-response application. Nothing is stored in the session. It could be load related, but I doubt it as there are only around 30 or 40 requests per minute. This is proving very tricky to track down. I can't work out what is putting IIS into this bad state, and why it needs an iisreset to get it working again. Nothing is reported in the event log. Can anyone suggest how to enable more extensive logging that might catch this fault? Also, does anyone know what might be causing the problem?

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  • Is .htaccess slowing down my dedicated server?

    - by David Robles
    First of all, I consider myself more a programmer than a servers guy. I have a website where I receive about 3,000 visits per day, which I think is a lot less than the max capacity for a dedicated server. However, I've noticed that the connection to the website is pretty slow, e.g., to load images, to connect to it via SSH, etc. I configured .httaccess recently to avoid hotlinking to images in my server (i.e. .jpg, .gif and .png), and I was wondering if that could be slowing down my website. This is the configuration that I have: # BEGIN WordPress <IfModule mod_rewrite.c> RewriteEngine On RewriteBase / RewriteEngine on RewriteCond %{HTTP_REFERER} !^$ RewriteCond %{HTTP_REFERER} !^http://www.mysite.com/.*$ [NC] RewriteCond %{HTTP_REFERER} !^http://www.mysite.com$ [NC] RewriteRule .*\.(jpg|jpeg|gif|png|bmp|swf)$ http://www.google.com/ [R,NC] RewriteCond %{REQUEST_FILENAME} !-f RewriteCond %{REQUEST_FILENAME} !-d RewriteRule . /index.php [L] </IfModule> # END WordPress I found some code to do that in google, and I just copied to .htacces since I'm not an expert in apache. It works, but I don't know if that is the best way to do it. How can I see if that is the reason why the server is slow? Are there any tools to monitor it? What would you do guys? Thanks in advance!

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  • Nagios check_host_alive and check_ping not showing host as down

    - by Kyle
    I am using the check_host_alive command to send 5 packets every minute to all my routers at remote locations. I noticed today I received a notification from The AT&T Global Client Support Center that a router was down (which can take 5-30 minutes to send these notices out) and never received a notice from Nagios. I went onto Nagios and it is was showing the host as alive with a latency of 0ms. This tells me it is seeing the automated response from my router in the data center that, "TTL expired in transit" as a reply from the remote router. Is there anyway for me to tell nagios to check where the reply is comming from? I feel like other people have to of had this issue... I tested it with the check_ping command and it produced the same results. I have the command defined has %hostname% and the proper IP in the host definition, and it works fine for telling me the latency is high. Any ideas are welcome, I have already exercised my Google skills with no results. EDIT: root@IM-UBTU:/# /usr/local/nagios/libexec/check_ping -H 192.168.250.1 -w 100.0,10% -c 200.0,20% -vvv CMD: /bin/ping -n -U -w 10 -c 5 192.168.250.1 Output: PING 192.168.250.1 (192.168.250.1) 56(84) bytes of data. Output: From 10.69.10.2 icmp_seq=1 Time to live exceeded It knows something is wrong why doesn't it give me a warning?

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  • Netbook (Samsung N220) on Ubuntu 10.04 slows down WiFi for other computers

    - by Joachim
    I encountered a really odd problem with my new netbook. I am running Ubuntu 10.04 on a Samsung N220 Mito. So far everything worked fine. Now I tried the machine for the first time in our work group where we have a wifi (with internet access) for all laptops. The wifi is controlled by a computer running Suse 9.3 which provides a DHCP server and imposes a firewall. At the moment there is only a macbook in the wifi, where no problems with the internet or wifi connection are encountered. Now coming to my actual problem: In addition to the macbook i connect the Samsung N220 to the Wifi. Problem: My download speed is for some reason limited to 70KB/s max. This is neither a limitation of the server/website i browse on, nor a configuration of the netbook: at home i have 500KB/s download speeds. Furthermore, it is not a default limitation for "untrusted" or "new machines" in the wifi, as for instance other new laptops get full speed internet with our wifi. Problem: Once the Samsung N220 is generating traffic in the wifi, the wifi is slowed down dramatically for all other machines: I run a ping to the router from the macbook. The ping times with the N220 ideling are 2-6ms. When I start downloading or browsing in the web with the N220 the ping speed drops to 800ms. Vice versa, when the macbook is generating the traffic the ping of the N220 to the rooter stays constant at around 2-6ms. So clearly, it is some problem originating from my netbook or maybe its treatment in the wifi. Thanks for any help

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  • Trying to connect simple VB6 ADO to SQL Server 2008

    - by Henry
    We have a VB6 App that -for current purposes - is very basic ADO: Dim a New ADODB.Recorset, set some basic properties like Cursor Location and Lock Type, set a Connection String and a .Source like "Select * from CustomerMaster", and .OPEN - nothing fancy here! Yet, on a new SBS installation with SQL Server 2008 across 2 Servers (one for Apps, the other dedicated to SQL!), it dies/hangs/crashes if you try to run such a Query from anything but the SQL Sever box. Initially, we were using the SQLOLEDB.1 driver, which would crash/hang the entire SQL Server after about 4 such queries (built a simple 6 line App just for this purpose). Then switched to the NATIVE SQL driver, which did allow us unlimited, happy queries - until you did the first Change/Update - THEN it would corrupt the SQL Server if you exited and tried to go back in. All this 'corruption' is happening from the 'App Server' of the SBS pair, and I presume that the App Server (also installed in tandem with the SQL server this week) has the latest MDACs, etc. And running it from a 'lowly XP workstation' is (obviously) no better. ANY ideas??? -Henry

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  • then an error occurred during the login process - Connection Error 233

    - by scott brunner
    We have SQL Server 2008 installed on 64Bit Windows Server 2003. When we try connect to the local SQL Server using SQL Server Management Studio at the console, we get the error: A connection was successfully established with the server, but then an error occurred during the login process. provider: Shared Memory Provider, error: 0 - No process is on the other end of the pipe. When we try TCP from same local SSMS to local server, we get the same error but intead of the pipe message its something like "connection forcibly closed". Now, here is the strange part - we CAN connect to this SQL Server from any other machine on the network using SSMS. - AND - WE CAN'T connect to ANY SQL Server from the problem server. So it seems the SQL Server instance is fine and accepting remote connections. However, the SSMS on that machine will not connect to any SQL Server even remotely. When we try an ADO.NET connection from C# remotely we can connect, run that same code on the console of the trouble server and we get the same errors. How can this be solved?

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  • Mysqld shutting down by itself

    - by AJ Naidas
    I'm running a Wordpress Blog that gets medium-high traffic. It is hosted in an Ubuntu Server 2GB Memory 2 Core Processor 40GB SSD Disk, 3TB Transfer. The problem is that MySQL shuts down by itself after an hour or two. I had to restart mysql each and every time this happens. I checked the logs and this is what I found: 140612 6:48:14 [Warning] Using unique option prefix myisam-recover instead of myisam-recover-options is deprecated and will be removed in a future release. Please use the full name instead. 140612 6:48:14 [Note] Plugin 'FEDERATED' is disabled. 140612 6:48:14 InnoDB: The InnoDB memory heap is disabled 140612 6:48:14 InnoDB: Mutexes and rw_locks use GCC atomic builtins 140612 6:48:14 InnoDB: Compressed tables use zlib 1.2.3.4 140612 6:48:14 InnoDB: Initializing buffer pool, size = 1.4G InnoDB: mmap(1502412800 bytes) failed; errno 12 140612 6:48:14 InnoDB: Completed initialization of buffer pool 140612 6:48:14 InnoDB: Fatal error: cannot allocate memory for the buffer pool 140612 6:48:14 [ERROR] Plugin 'InnoDB' init function returned error. 140612 6:48:14 [ERROR] Plugin 'InnoDB' registration as a STORAGE ENGINE failed. 140612 6:48:14 [ERROR] Unknown/unsupported storage engine: InnoDB 140612 6:48:14 [ERROR] Aborting 140612 6:48:14 [Note] /usr/sbin/mysqld: Shutdown complete judging by this line: 140612 6:48:14 InnoDB: Fatal error: cannot allocate memory for the buffer pool I suspect that this is a memory problem, but I would like to hear from the experts here before I conclude. Is this a lack of memory problem? Do you think the value of max_connections in my.cnf (currently 100) is a potential cause and needs increasing? TIA.

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  • Jailkit not locking down SFTP, working for SSH

    - by doublesharp
    I installed jailkit on my CentOS 5.8 server, and configured it according to the online guides that I found. These are the commands that were executed as root: mkdir /var/jail jk_init -j /var/jail extshellplusnet jk_init -j /var/jail sftp adduser testuser; passwd testuser jk_jailuser -j /var/jail testuser I then edited /var/jail/etc/passwd to change the login shell for testuser to be /bin/bash to give them access to a full bash shell via SSH. Next I edited /var/jail/etc/jailkit/jk_lsh.ini to look like the following (not sure if this is correct) [testuser] paths= /usr/bin, /usr/lib/ executables= /usr/bin/scp, /usr/lib/openssh/sftp-server, /usr/bin/sftp The testuser is able to connect via SSH and is limited to only view the chroot jail directory, and is also able to log in via SFTP, however the entire file system is visible and can be traversed. SSH Output: > ssh testuser@server Password: Last login: Sat Oct 20 03:26:19 2012 from x.x.x.x bash-3.2$ pwd /home/testuser SFTP Output: > sftp testuser@server Password: Connected to server. sftp> pwd Remote working directory: /var/jail/home/testuser What can be done to lock down SFTP access to the jail? FWIW, I mostly used this as a guide: http://digitalpatch.blogspot.com.ar/2010/03/openssh-daemon-hardening-part-3-setup.html

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  • Device CAL, User Cal or Processor license needed for SQL 2008 (architecture explained inside)?

    - by nycgags
    So we have a number of servers in the Amazon cloud running SQL Server Standard edition to aggregate data. For that purpose we are fine, the licensing is handled by our contract with Amazon, no problem there. For the beefier work, we want to install Enterprise Edition (EE) on our servers processing raw data so that we can take advantage of table partitioning. We currently have 3 servers aggregating data from about 40 node servers, all 43 of these servers are running standard edition which is fine. We also have 4 servers running standard processing the raw data, but I think we can get away with 2 (for redundancy) running Enterprise Edition. We have 2-3 dba's that access these DW servers for maintenance (using the same windows login via remote desktop). So visually: 40 -- 3 -- [2] -- 2 -- 1 nodes -- aggregators -- raw (which we want to run EE) -- calculators -- datawarehouse Nodes PUSH to aggregators, Raws PULL from aggregators, Calculators PULL from Raw, Calculators PUSH to datwarehouse I am specifying the push vs. pull in case that changes how the # of licenses is calculated. Q1) how many device (or user) CAL's do we need? Q2) do I need to speak with someone from MSFT to find out if it is ok to install in the Amazon Cloud (Amazon said we need to verify it is ok in our license terms)? Q3) what happens if another device tries to access a server with the limited number of device CAL's? Q4) Are the device CAL's simultaneous number of devices or total? Q5) Do Device and User CAL's cost the same or is there a difference? Q6) Would we need to buy a processor license (we are hoping not to)?

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  • Alternative method of viewing a database diagram in SQL Server to see what tables have gone missing?

    - by Triynko
    I have a database diagram for my database, but when I open it in SQL Server, I almost immediately get a message saying some permissions changed or tables in the diagram were dropped or renamed, and tables in the diagram vanish before I can even scroll over to see what or where they were. Basically, it's saying, "Hey, you know all that time you spent laying out tables in this diagram... half of them are going to vanish when you view it, and I'm not going to tell you which tables vanished or where they were in the diagram. You're just going to see a bunch of random empty spaces where tables used to be ;)" Ridiculous. So I thought that maybe if I look in the dbo.sysdiagrams table, I could look at some plain text definition of the diagram to get a clue about the names of the tables that went missing (because thier names were probably only changed slightly) or their coordinates in the diagram (because their spatial location would give me a clue as to what they were), so that I could re-add them, but I can't, because it's a binary definition. So, is there some other program I could use to view the existing database diagram that's not going to just drop and forget the missing tables without telling me what they were, or is this information lost and at the mercy of some SSMS-proprietary database diagram format and viewer which refuses to cooperate with me.

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  • Fill down in Excel, but based on multiple values

    - by Jenn D.
    I have spreadsheets (not created by me) that have blank entries in one column where they should really have data. I want to take every empty cell and fill it with the nearest value above it. I'm looking for as little manual intervention as possible, because I'll have to do it repeatedly. I thought some previous version of Excel, or maybe another spreadsheet from the distant past, would do this by default -- that is, if you selected the column with foo and bar, and chose the equivalent of "fill down", you would get what's in the WANT column. What I actually get in Excel is the GET column. HAVE: WANT: GET: foo 1 foo 1 foo 1 2 foo 2 foo 2 bar 1 bar 1 foo 1 2 bar 2 foo 2 3 bar 3 foo 3 I'm worried that this might need a macro to be done properly. I used to be a whiz with Excel macros, and then suddenly they were all in VB. My fallback position will be to dump the whole thing to CSV and write a Python script, but if there's any way to do it in Excel that would be much preferable. Even if it involves a couple of different manual steps, that's fine; just not one step per group of lines. That is, a process of "copy the column, do X to it, cut and paste it back" would work, but "do X for each occurrence of foo or bar" won't. The files are too big for that. Any thoughts are appreciated!

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  • Network card shuts down when stressed

    - by user142485
    I have a network card that functions fine with light use, but quits functioning after heavy use. I replaced it with a brand new one and still have the same issue, also updated drivers. It is a wired D-Link card. The Internet seems fine for a small amount of web browsing but when I run a bandwidth test it starts out fast and slows quickly until the card completely quits; I have a constant ping of the gateway going while I run this and it starts timing out after a couple seconds into the speed test. The card will stay on and the data light on it still flashes some but I cannot ping the gateway or anything else until the computer is rebooted. When I boot into safe mode I can browse and run the speed test fine with no problems. I am guessing that this is probably some program that is loading in regular mode but not safe mode that is causing the issue? I have very limited software (turned off av and firewall) on the computer but I am thinking that I'll just have to start eliminating start-up programs and see if that helps. This is on Windows 7 if that makes any difference. Anyone had a similar issue or have any other suggestions/ideas for narrowing down this problem?

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  • Active Directory server down, recovering without reinstalling

    - by whatever
    My Windows 2003 server suddenly ceased to function as a DC (this server is the only DC of the domain). All AD related services are down. The only way I can login to the AD is physically to the machine. Everytime I access an AD-related service (e.g. "AD users and computers") I get the below error: Naming information cannot be located because: The specified directory service attribute or value does not exist. Contact your system administrator to verify that your domain is properly configured and is currently online. I found the below system event which matches the time when the issue started, this re-occurs everytime I reboot the server. NTDS General | Global Catalog | Active Directory was unable to establish a connection with the global catalog. Additional Data Error value: 1355 The specified domain either does not exist or could not be contacted. Internal ID: 3200d33 I started the troubleshooting with DNS. Netdiag throws the below error although I think this is simply a consequence of not being able to access the Global Catalog. The procedure entry point DnsGetPrimaryDomainName_UTF8 could not be located in the dynamic link library DNSAPI.dll. Anyway DNS seems OK because I can ping the DC FQDN from the DC itself. I found the below solution which is supposed to help by doing some cleanup of the metadata: http://support.microsoft.com/kb/216498 If I follow procedure 1 here is what I get at step 9: no current site Domain - DC=<mydomain>,DC=<com> no current server no current naming context I can continue the procedure until step 14. I haven't tested step 15 as my understanding is that I will have to reinstall the whole AD again. Is there any way I can recover my AD from there without having to reinstall the whole thing? Update: Yes, the server was powered off/on because reboot would take forever (not because I thought power cycling the unit would fix it more than a reboot).

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  • Why would my network slow down?

    - by monkthemighty
    The network at my work has about 40 computers on it and a quite a few printers. When there are a lot of people working the network will be slow. I can test the ping between my computer and the router and it will keep rising, sometimes to the point that it times out. The router we are using is running Ubuntu on a atom processor and it has 4gb of ram. When the network slows the process Ksoftirq will be using most if not all of the processing power. I have found that Ksoftirq is a process that handles irq requests. Also when the network slows down I have captured packets from the router and using tshark and looked at it using wireshark on my laptop. With the capture show a lot of packets with TCP Dup ACK and TCP Retransmissions. The destinations of the TCP Dup and TCP retransmissions are to most of the computers on the network but there are some that are far more than others. What could this problem be caused by?

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  • Server down at 23:26 every night

    - by miccet
    We are having a big problem with our sites stability the last couple of weeks and after endless hours of troubleshooting I don't get anywhere. So I turn to you dear community. Setup: 2 x VPS servers - Front end, 8 core, 8G RAM. - Database, 5 core, 3G RAM. Both running Ubuntu. Ruby on Rails EE with Passenger 3 and Rails 2.3.11. MySQL 5.1.67. The problem is that each night, at the exact same time (23:26) the SQL server suddenly shows a processlist full of COMMIT with an increasing Time. After 30-40 seconds (can go longer) a wave seems processed and the site responds for a few seconds before it repeats. During this hick up the database server load spikes while the front end is relaxing. I have looked at slow queries, but is not finding any locks or other unusual queries ran at this time. I have looked at iotop at the time of the halt and there is no activity from mysql. I also tried turning off query_cache and messed around with the mysql configuration file without much change. Any ideas?

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  • Web Server slows down (ASP.NET)

    - by mfeingold
    below is a question I posted on stackoverflow . as suggested by Martin Clarke I also post it here. We have a really strange problem. One of the servers in the server farm becomes really slow. We see a number of timeouts in the logs and overall response time is not where it should be (and is on other servers in the farm). What is also strange is that it is not just the web app - Just logging into the server takes up to 1.5 min to show you the desktop. Once you are in, the system is as responsive as ever - unless you try to launch something, i.e. notepad - it takes another minute to launch and after launch it works fine. I checked a number of things - memory utilization is reasonable, CPU is below 15%, windows handles, event logs do not show anything. Recycling the aps.net process does not fix it - it still takes over a minute to log in. Rebooting the server helped, but now it started to slow down again. After a closer look we found out that Windows Temp directory is full of temp files - over 65k files. This is certainly something to take care of. But my question is could it be the root cause of the sluggishness, or there is still something else lurking in the shadows? Edit After more digging I am zeroing in on the issue related to the size of temp directories. This article: (see the original post this thing will not let me include a second link) describes something very similar. It still does not answer the question why the server is still slow even there is no activity.

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  • Cannot open /dev/rfcomm1 : Host is down

    - by srj0408
    I am working on raspberry PI and on Bluetooth. I am using old raspberry pi kernel as the new one has got some bugs that were not resolved with respect to the bluez daemon. At present my kernel version is 3.6.11. I am using a USB bluetooth dongle and my sole purpose is to auto connect the bluetooth dongle when ever it is in range. For that i think i have to run a script in the backend on RPI that will keep on checking the existence of usb bluetooth dongle. I started from the very scratch. I installed bluez daemon using apt-get install bluetooth bluez utils blueman and then i used hciconfig which gives me that my bluetooth usb dongle is working fine. But when i did hcitool scan , it give me no device in range even though my Serial bluetooth Device was on. I wasn't able to find any device in vicinity. Also when i unplugged and plug the USB dongle again, i was able to scan the serial device , but when i repeat the process, i find the earlier condition of not finding any deice. I had find another useful link, but that need address of the bluetooth device that need to be connected. I want to automate this using hcitool scan, storing the output to the a file and then comparing it with already paired devices and their name. For that i need to figure out why hcitool scan is sometime working and sometime not. ? Can some one help me in figuring out why this is happening. Is there any problem on hardware side i.e Bluetooth dongle is buggy or i had some problem in bluez utils. Edit 1: While as of now, hcitool scan is giving me my remote device address but still i am getting the same issue of HOUST IS DOWN, '/dev/rfcomm1'. I am really not getting any idea of what to be done.

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  • Interview with Geoff Bones, developer on SQL Storage Compress

    - by red(at)work
    How did you come to be working at Red Gate? I've been working at Red Gate for nine months; before that I had been at a multinational engineering company. A number of my colleagues had left to work at Red Gate and spoke very highly of it, but I was happy in my role and thought, 'It can't be that great there, surely? They'll be back!' Then one day I visited to catch up them over lunch in the Red Gate canteen. I was so impressed with what I found there, that, three days later, I'd applied for a role as a developer. And how did you get into software development? My first job out of university was working as a systems programmer on IBM mainframes. This was quite a while ago: there was a lot of assembler and loading programs from tape drives and that kind of stuff. I learned a lot about how computers work, and this stood me in good stead when I moved over the development in the 90s. What's the best thing about working as a developer at Red Gate? Where should I start? One of the great things as a developer at Red Gate is the useful feedback and close contact we have with the people who use our products, either directly at trade shows and other events or through information coming through the product managers. The company's whole ethos is built around assisting the user, and this is in big contrast to my previous development roles. We aim to produce tools that people really want to use, that they enjoy using, and, as a developer, this is a great thing to aim for and a great feeling when we get it right. At Red Gate we also try to cut out the things that distract and stop us doing our jobs. As a developer, this means that I can focus on the code and the product I'm working on, knowing that others are doing a first-class job of making sure that the builds are running smoothly and that I'm getting great feedback from the testers. We keep our process light and effective, as we want to produce great software more than we want to produce great audit trails. Tell us a bit about the products you are currently working on. You mean HyperBac? First let me explain a bit about what HyperBac is. At heart it's a compression and encryption technology, but with a few added features that open up a wealth of really exciting possibilities. Right now we have the HyperBac technology in just three products: SQL HyperBac, SQL Virtual Restore and SQL Storage Compress, but we're only starting to develop what it can do. My personal favourite is SQL Virtual Restore; for example, I love the way you can use it to run independent test databases that are all backed by a single compressed backup. I don't think the market yet realises the kind of things you do once you are using these products. On the other hand, the benefits of SQL Storage Compress are straightforward: run your databases but use only 20% of the disk space. Databases are getting larger and larger, and, as they do, so does your ROI. What's a typical day for you? My days are pretty varied. We have our daily team stand-up meeting and then sometimes I will work alone on a current issue, or I'll be pair programming with one of my colleagues. From time to time we give half a day up to future planning with the team, when we look at the long and short term aims for the product and working out the development priorities. I also get to go to conferences and events, which is unusual for a development role and gives me the chance to meet and talk to our customers directly. Have you noticed anything different about developing tools for DBAs rather than other IT kinds of user? It seems to me that DBAs are quite independent minded; they know exactly what the problem they are facing is, and often have a solution in mind before they begin to look for what's on the market. This means that they're likely to cherry-pick tools from a range of vendors, picking the ones that are the best fit for them and that disrupt their environments the least. When I've met with DBAs, I've often been very impressed at their ability to summarise their set up, the issues, the obstacles they face when implementing a tool and their plans for their environment. It's easier to develop products for this audience as they give such a detailed overview of their needs, and I feel I understand their problems.

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  • Building dynamic OLAP data marts on-the-fly

    - by DrJohn
    At the forthcoming SQLBits conference, I will be presenting a session on how to dynamically build an OLAP data mart on-the-fly. This blog entry is intended to clarify exactly what I mean by an OLAP data mart, why you may need to build them on-the-fly and finally outline the steps needed to build them dynamically. In subsequent blog entries, I will present exactly how to implement some of the techniques involved. What is an OLAP data mart? In data warehousing parlance, a data mart is a subset of the overall corporate data provided to business users to meet specific business needs. Of course, the term does not specify the technology involved, so I coined the term "OLAP data mart" to identify a subset of data which is delivered in the form of an OLAP cube which may be accompanied by the relational database upon which it was built. To clarify, the relational database is specifically create and loaded with the subset of data and then the OLAP cube is built and processed to make the data available to the end-users via standard OLAP client tools. Why build OLAP data marts? Market research companies sell data to their clients to make money. To gain competitive advantage, market research providers like to "add value" to their data by providing systems that enhance analytics, thereby allowing clients to make best use of the data. As such, OLAP cubes have become a standard way of delivering added value to clients. They can be built on-the-fly to hold specific data sets and meet particular needs and then hosted on a secure intranet site for remote access, or shipped to clients' own infrastructure for hosting. Even better, they support a wide range of different tools for analytical purposes, including the ever popular Microsoft Excel. Extension Attributes: The Challenge One of the key challenges in building multiple OLAP data marts based on the same 'template' is handling extension attributes. These are attributes that meet the client's specific reporting needs, but do not form part of the standard template. Now clearly, these extension attributes have to come into the system via additional files and ultimately be added to relational tables so they can end up in the OLAP cube. However, processing these files and filling dynamically altered tables with SSIS is a challenge as SSIS packages tend to break as soon as the database schema changes. There are two approaches to this: (1) dynamically build an SSIS package in memory to match the new database schema using C#, or (2) have the extension attributes provided as name/value pairs so the file's schema does not change and can easily be loaded using SSIS. The problem with the first approach is the complexity of writing an awful lot of complex C# code. The problem of the second approach is that name/value pairs are useless to an OLAP cube; so they have to be pivoted back into a proper relational table somewhere in the data load process WITHOUT breaking SSIS. How this can be done will be part of future blog entry. What is involved in building an OLAP data mart? There are a great many steps involved in building OLAP data marts on-the-fly. The key point is that all the steps must be automated to allow for the production of multiple OLAP data marts per day (i.e. many thousands, each with its own specific data set and attributes). Now most of these steps have a great deal in common with standard data warehouse practices. The key difference is that the databases are all built to order. The only permanent database is the metadata database (shown in orange) which holds all the metadata needed to build everything else (i.e. client orders, configuration information, connection strings, client specific requirements and attributes etc.). The staging database (shown in red) has a short life: it is built, populated and then ripped down as soon as the OLAP Data Mart has been populated. In the diagram below, the OLAP data mart comprises the two blue components: the Data Mart which is a relational database and the OLAP Cube which is an OLAP database implemented using Microsoft Analysis Services (SSAS). The client may receive just the OLAP cube or both components together depending on their reporting requirements.  So, in broad terms the steps required to fulfil a client order are as follows: Step 1: Prepare metadata Create a set of database names unique to the client's order Modify all package connection strings to be used by SSIS to point to new databases and file locations. Step 2: Create relational databases Create the staging and data mart relational databases using dynamic SQL and set the database recovery mode to SIMPLE as we do not need the overhead of logging anything Execute SQL scripts to build all database objects (tables, views, functions and stored procedures) in the two databases Step 3: Load staging database Use SSIS to load all data files into the staging database in a parallel operation Load extension files containing name/value pairs. These will provide client-specific attributes in the OLAP cube. Step 4: Load data mart relational database Load the data from staging into the data mart relational database, again in parallel where possible Allocate surrogate keys and use SSIS to perform surrogate key lookup during the load of fact tables Step 5: Load extension tables & attributes Pivot the extension attributes from their native name/value pairs into proper relational tables Add the extension attributes to the views used by OLAP cube Step 6: Deploy & Process OLAP cube Deploy the OLAP database directly to the server using a C# script task in SSIS Modify the connection string used by the OLAP cube to point to the data mart relational database Modify the cube structure to add the extension attributes to both the data source view and the relevant dimensions Remove any standard attributes that not required Process the OLAP cube Step 7: Backup and drop databases Drop staging database as it is no longer required Backup data mart relational and OLAP database and ship these to the client's infrastructure Drop data mart relational and OLAP database from the build server Mark order complete Start processing the next order, ad infinitum. So my future blog posts and my forthcoming session at the SQLBits conference will all focus on some of the more interesting aspects of building OLAP data marts on-the-fly such as handling the load of extension attributes and how to dynamically alter the structure of an OLAP cube using C#.

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  • SQL University: What and why of database refactoring

    - by Mladen Prajdic
    This is a post for a great idea called SQL University started by Jorge Segarra also famously known as SqlChicken on Twitter. It’s a collection of blog posts on different database related topics contributed by several smart people all over the world. So this week is mine and we’ll be talking about database testing and refactoring. In 3 posts we’ll cover: SQLU part 1 - What and why of database testing SQLU part 2 - What and why of database refactoring SQLU part 3 - Tools of the trade This is a second part of the series and in it we’ll take a look at what database refactoring is and why do it. Why refactor a database To know why refactor we first have to know what refactoring actually is. Code refactoring is a process where we change module internals in a way that does not change that module’s input/output behavior. For successful refactoring there is one crucial thing we absolutely must have: Tests. Automated unit tests are the only guarantee we have that we haven’t broken the input/output behavior before refactoring. If you haven’t go back ad read my post on the matter. Then start writing them. Next thing you need is a code module. Those are views, UDFs and stored procedures. By having direct table access we can kiss fast and sweet refactoring good bye. One more point to have a database abstraction layer. And no, ORM’s don’t fall into that category. But also know that refactoring is NOT adding new functionality to your code. Many have fallen into this trap. Don’t be one of them and resist the lure of the dark side. And it’s a strong lure. We developers in general love to add new stuff to our code, but hate fixing our own mistakes or changing existing code for no apparent reason. To be a good refactorer one needs discipline and focus. Now we know that refactoring is all about changing inner workings of existing code. This can be due to performance optimizations, changing internal code workflows or some other reason. This is a typical black box scenario to the outside world. If we upgrade the car engine it still has to drive on the road (preferably faster) and not fly (no matter how cool that would be). Also be aware that white box tests will break when we refactor. What to refactor in a database Refactoring databases doesn’t happen that often but when it does it can include a lot of stuff. Let us look at a few common cases. Adding or removing database schema objects Adding, removing or changing table columns in any way, adding constraints, keys, etc… All of these can be counted as internal changes not visible to the data consumer. But each of these carries a potential input/output behavior change. Dropping a column can result in views not working anymore or stored procedure logic crashing. Adding a unique constraint shows duplicated data that shouldn’t exist. Foreign keys break a truncate table command executed from an application that runs once a month. All these scenarios are very real and can happen. With the proper database abstraction layer fully covered with black box tests we can make sure something like that does not happen (hopefully at all). Changing physical structures Physical structures include heaps, indexes and partitions. We can pretty much add or remove those without changing the data returned by the database. But the performance can be affected. So here we use our performance tests. We do have them, right? Just by adding a single index we can achieve orders of magnitude performance improvement. Won’t that make users happy? But what if that index causes our write operations to crawl to a stop. again we have to test this. There are a lot of things to think about and have tests for. Without tests we can’t do successful refactoring! Fixing bad code We all have some bad code in our systems. We usually refer to that code as code smell as they violate good coding practices. Examples of such code smells are SQL injection, use of SELECT *, scalar UDFs or cursors, etc… Each of those is huge code smell and can result in major code changes. Take SELECT * from example. If we remove a column from a table the client using that SELECT * statement won’t have a clue about that until it runs. Then it will gracefully crash and burn. Not to mention the widely unknown SELECT * view refresh problem that Tomas LaRock (@SQLRockstar on Twitter) and Colin Stasiuk (@BenchmarkIT on Twitter) talk about in detail. Go read about it, it’s informative. Refactoring this includes replacing the * with column names and most likely change to application using the database. Breaking apart huge stored procedures Have you ever seen seen a stored procedure that was 2000 lines long? I have. It’s not pretty. It hurts the eyes and sucks the will to live the next 10 minutes. They are a maintenance nightmare and turn into things no one dares to touch. I’m willing to bet that 100% of time they don’t have a single test on them. Large stored procedures (and functions) are a clear sign that they contain business logic. General opinion on good database coding practices says that business logic has no business in the database. That’s the applications part. Refactoring such behemoths requires writing lots of edge case tests for the stored procedure input/output behavior and then start to refactor it. First we split the logic inside into smaller parts like new stored procedures and UDFs. Those then get called from the master stored procedure. Once we’ve successfully modularized the database code it’s best to transfer that logic into the applications consuming it. This only leaves the stored procedure with common data manipulation logic. Of course this isn’t always possible so having a plethora of performance and behavior unit tests is absolutely necessary to confirm we’ve actually improved the codebase in some way.   Refactoring is not a popular chore amongst developers or managers. The former don’t like fixing old code, the latter can’t see the financial benefit. Remember how we talked about being lousy at estimating future costs in the previous post? But there comes a time when it must be done. Hopefully I’ve given you some ideas how to get started. In the last post of the series we’ll take a look at the tools to use and an example of testing and refactoring.

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