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  • How to measure disk-performance under Windows?

    - by Alphager
    I'm trying to find out why my application is very slow on a certain machine (runs fine everywhere else). I think i have traced the performance-problems to hard-disk reads and writes and i think it's simply the very slow disk. What tool could i use to measure hd read and write performance under Windows 2003 in a non-destructive way (the partitions on the drives have to remain intact)?

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  • SQL Saturday Atlanta: Intro To Performance Tuning

    - by Mike Femenella
    I'm looking forward to speaking in Atlanta on the 24th, will be fun to get back down that way to visit with some friends and present two topics that I really enjoy. First, an introduction to performance tuning. Performance tuning is a very wide and deep topic and we're staying close to the surface. I direct this class for newbie sql users who have less than 2 years of experience. It's all the things I wish someone would have told me in my first 2 years about what to look for when the database was slow...or allegedly slow I should say. We'll cover using profiler to find slow performing queries and how to save the data off to a table as well as a tour of other features. The difference between clustered, non clustered and covering indexes. How to look at and understand an execution plan (at a high level) and finally the difference between a temp table and a table variable and what the implications are of using either one in your code. That pretty much takes up a full hour. Second presentation, Loading Data in Real Time. It's really a presentation about partitioning but with a twist that we used at work recently to solve a need to load some data quickly and put it into production with minimal downtime. We'll cover partition functions, schemes,$partition, merge, sys.partitions and show some examples of building a set of partitioned tables and using the switch statement to move it from one table to another. Finally we'll cover the differences in partitioning between 2005 and 2008. Hope to see you there! And if you read my blog please introduce yourself!

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  • Getting started with tuning your SOA/BPM database using AWR

    - by Mark Nelson
    In order to continue to get good performance from your SOA or BPM 11g server, you will want to periodically check your database – the one you are storing your SOAINFRA schema in – to see if there are any performance issues there. This article provides a very brief introduction to the use of the Automatic Workload Repository (AWR) in the Oracle Database and what to look for in the reports for your SOA/BPM environment. READ MORE >>

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  • More CPU cores may not always lead to better performance – MAXDOP and query memory distribution in spotlight

    - by sqlworkshops
    More hardware normally delivers better performance, but there are exceptions where it can hinder performance. Understanding these exceptions and working around it is a major part of SQL Server performance tuning.   When a memory allocating query executes in parallel, SQL Server distributes memory to each task that is executing part of the query in parallel. In our example the sort operator that executes in parallel divides the memory across all tasks assuming even distribution of rows. Common memory allocating queries are that perform Sort and do Hash Match operations like Hash Join or Hash Aggregation or Hash Union.   In reality, how often are column values evenly distributed, think about an example; are employees working for your company distributed evenly across all the Zip codes or mainly concentrated in the headquarters? What happens when you sort result set based on Zip codes? Do all products in the catalog sell equally or are few products hot selling items?   One of my customers tested the below example on a 24 core server with various MAXDOP settings and here are the results:MAXDOP 1: CPU time = 1185 ms, elapsed time = 1188 msMAXDOP 4: CPU time = 1981 ms, elapsed time = 1568 msMAXDOP 8: CPU time = 1918 ms, elapsed time = 1619 msMAXDOP 12: CPU time = 2367 ms, elapsed time = 2258 msMAXDOP 16: CPU time = 2540 ms, elapsed time = 2579 msMAXDOP 20: CPU time = 2470 ms, elapsed time = 2534 msMAXDOP 0: CPU time = 2809 ms, elapsed time = 2721 ms - all 24 cores.In the above test, when the data was evenly distributed, the elapsed time of parallel query was always lower than serial query.   Why does the query get slower and slower with more CPU cores / higher MAXDOP? Maybe you can answer this question after reading the article; let me know: [email protected].   Well you get the point, let’s see an example.   The best way to learn is to practice. To create the below tables and reproduce the behavior, join the mailing list by using this link: www.sqlworkshops.com/ml and I will send you the table creation script.   Let’s update the Employees table with 49 out of 50 employees located in Zip code 2001. update Employees set Zip = EmployeeID / 400 + 1 where EmployeeID % 50 = 1 update Employees set Zip = 2001 where EmployeeID % 50 != 1 go update statistics Employees with fullscan go   Let’s create the temporary table #FireDrill with all possible Zip codes. drop table #FireDrill go create table #FireDrill (Zip int primary key) insert into #FireDrill select distinct Zip from Employees update statistics #FireDrill with fullscan go  Let’s execute the query serially with MAXDOP 1. --Example provided by www.sqlworkshops.com --Execute query with uneven Zip code distribution --First serially with MAXDOP 1 set statistics time on go declare @EmployeeID int, @EmployeeName varchar(48),@zip int select @EmployeeName = e.EmployeeName, @zip = e.Zip from Employees e       inner join #FireDrill fd on (e.Zip = fd.Zip)       order by e.Zip option (maxdop 1) goThe query took 1011 ms to complete.   The execution plan shows the 77816 KB of memory was granted while the estimated rows were 799624.  No Sort Warnings in SQL Server Profiler.  Now let’s execute the query in parallel with MAXDOP 0. --Example provided by www.sqlworkshops.com --Execute query with uneven Zip code distribution --In parallel with MAXDOP 0 set statistics time on go declare @EmployeeID int, @EmployeeName varchar(48),@zip int select @EmployeeName = e.EmployeeName, @zip = e.Zip from Employees e       inner join #FireDrill fd on (e.Zip = fd.Zip)       order by e.Zip option (maxdop 0) go The query took 1912 ms to complete.  The execution plan shows the 79360 KB of memory was granted while the estimated rows were 799624.  The estimated number of rows between serial and parallel plan are the same. The parallel plan has slightly more memory granted due to additional overhead. Sort properties shows the rows are unevenly distributed over the 4 threads.   Sort Warnings in SQL Server Profiler.   Intermediate Summary: The reason for the higher duration with parallel plan was sort spill. This is due to uneven distribution of employees over Zip codes, especially concentration of 49 out of 50 employees in Zip code 2001. Now let’s update the Employees table and distribute employees evenly across all Zip codes.   update Employees set Zip = EmployeeID / 400 + 1 go update statistics Employees with fullscan go  Let’s execute the query serially with MAXDOP 1. --Example provided by www.sqlworkshops.com --Execute query with uneven Zip code distribution --Serially with MAXDOP 1 set statistics time on go declare @EmployeeID int, @EmployeeName varchar(48),@zip int select @EmployeeName = e.EmployeeName, @zip = e.Zip from Employees e       inner join #FireDrill fd on (e.Zip = fd.Zip)       order by e.Zip option (maxdop 1) go   The query took 751 ms to complete.  The execution plan shows the 77816 KB of memory was granted while the estimated rows were 784707.  No Sort Warnings in SQL Server Profiler.   Now let’s execute the query in parallel with MAXDOP 0. --Example provided by www.sqlworkshops.com --Execute query with uneven Zip code distribution --In parallel with MAXDOP 0 set statistics time on go declare @EmployeeID int, @EmployeeName varchar(48),@zip int select @EmployeeName = e.EmployeeName, @zip = e.Zip from Employees e       inner join #FireDrill fd on (e.Zip = fd.Zip)       order by e.Zip option (maxdop 0) go The query took 661 ms to complete.  The execution plan shows the 79360 KB of memory was granted while the estimated rows were 784707.  Sort properties shows the rows are evenly distributed over the 4 threads. No Sort Warnings in SQL Server Profiler.    Intermediate Summary: When employees were distributed unevenly, concentrated on 1 Zip code, parallel sort spilled while serial sort performed well without spilling to tempdb. When the employees were distributed evenly across all Zip codes, parallel sort and serial sort did not spill to tempdb. This shows uneven data distribution may affect the performance of some parallel queries negatively. For detailed discussion of memory allocation, refer to webcasts available at www.sqlworkshops.com/webcasts.     Some of you might conclude from the above execution times that parallel query is not faster even when there is no spill. Below you can see when we are joining limited amount of Zip codes, parallel query will be fasted since it can use Bitmap Filtering.   Let’s update the Employees table with 49 out of 50 employees located in Zip code 2001. update Employees set Zip = EmployeeID / 400 + 1 where EmployeeID % 50 = 1 update Employees set Zip = 2001 where EmployeeID % 50 != 1 go update statistics Employees with fullscan go  Let’s create the temporary table #FireDrill with limited Zip codes. drop table #FireDrill go create table #FireDrill (Zip int primary key) insert into #FireDrill select distinct Zip       from Employees where Zip between 1800 and 2001 update statistics #FireDrill with fullscan go  Let’s execute the query serially with MAXDOP 1. --Example provided by www.sqlworkshops.com --Execute query with uneven Zip code distribution --Serially with MAXDOP 1 set statistics time on go declare @EmployeeID int, @EmployeeName varchar(48),@zip int select @EmployeeName = e.EmployeeName, @zip = e.Zip from Employees e       inner join #FireDrill fd on (e.Zip = fd.Zip)       order by e.Zip option (maxdop 1) go The query took 989 ms to complete.  The execution plan shows the 77816 KB of memory was granted while the estimated rows were 785594. No Sort Warnings in SQL Server Profiler.  Now let’s execute the query in parallel with MAXDOP 0. --Example provided by www.sqlworkshops.com --Execute query with uneven Zip code distribution --In parallel with MAXDOP 0 set statistics time on go declare @EmployeeID int, @EmployeeName varchar(48),@zip int select @EmployeeName = e.EmployeeName, @zip = e.Zip from Employees e       inner join #FireDrill fd on (e.Zip = fd.Zip)       order by e.Zip option (maxdop 0) go The query took 1799 ms to complete.  The execution plan shows the 79360 KB of memory was granted while the estimated rows were 785594.  Sort Warnings in SQL Server Profiler.    The estimated number of rows between serial and parallel plan are the same. The parallel plan has slightly more memory granted due to additional overhead.  Intermediate Summary: The reason for the higher duration with parallel plan even with limited amount of Zip codes was sort spill. This is due to uneven distribution of employees over Zip codes, especially concentration of 49 out of 50 employees in Zip code 2001.   Now let’s update the Employees table and distribute employees evenly across all Zip codes. update Employees set Zip = EmployeeID / 400 + 1 go update statistics Employees with fullscan go Let’s execute the query serially with MAXDOP 1. --Example provided by www.sqlworkshops.com --Execute query with uneven Zip code distribution --Serially with MAXDOP 1 set statistics time on go declare @EmployeeID int, @EmployeeName varchar(48),@zip int select @EmployeeName = e.EmployeeName, @zip = e.Zip from Employees e       inner join #FireDrill fd on (e.Zip = fd.Zip)       order by e.Zip option (maxdop 1) go The query took 250  ms to complete.  The execution plan shows the 9016 KB of memory was granted while the estimated rows were 79973.8.  No Sort Warnings in SQL Server Profiler.  Now let’s execute the query in parallel with MAXDOP 0.  --Example provided by www.sqlworkshops.com --Execute query with uneven Zip code distribution --In parallel with MAXDOP 0 set statistics time on go declare @EmployeeID int, @EmployeeName varchar(48),@zip int select @EmployeeName = e.EmployeeName, @zip = e.Zip from Employees e       inner join #FireDrill fd on (e.Zip = fd.Zip)       order by e.Zip option (maxdop 0) go The query took 85 ms to complete.  The execution plan shows the 13152 KB of memory was granted while the estimated rows were 784707.  No Sort Warnings in SQL Server Profiler.    Here you see, parallel query is much faster than serial query since SQL Server is using Bitmap Filtering to eliminate rows before the hash join.   Parallel queries are very good for performance, but in some cases it can hinder performance. If one identifies the reason for these hindrances, then it is possible to get the best out of parallelism. I covered many aspects of monitoring and tuning parallel queries in webcasts (www.sqlworkshops.com/webcasts) and articles (www.sqlworkshops.com/articles). I suggest you to watch the webcasts and read the articles to better understand how to identify and tune parallel query performance issues.   Summary: One has to avoid sort spill over tempdb and the chances of spills are higher when a query executes in parallel with uneven data distribution. Parallel query brings its own advantage, reduced elapsed time and reduced work with Bitmap Filtering. So it is important to understand how to avoid spills over tempdb and when to execute a query in parallel.   I explain these concepts with detailed examples in my webcasts (www.sqlworkshops.com/webcasts), I recommend you to watch them. The best way to learn is to practice. To create the above tables and reproduce the behavior, join the mailing list at www.sqlworkshops.com/ml and I will send you the relevant SQL Scripts.   Register for the upcoming 3 Day Level 400 Microsoft SQL Server 2008 and SQL Server 2005 Performance Monitoring & Tuning Hands-on Workshop in London, United Kingdom during March 15-17, 2011, click here to register / Microsoft UK TechNet.These are hands-on workshops with a maximum of 12 participants and not lectures. For consulting engagements click here.   Disclaimer and copyright information:This article refers to organizations and products that may be the trademarks or registered trademarks of their various owners. Copyright of this article belongs to R Meyyappan / www.sqlworkshops.com. You may freely use the ideas and concepts discussed in this article with acknowledgement (www.sqlworkshops.com), but you may not claim any of it as your own work. This article is for informational purposes only; you use any of the suggestions given here entirely at your own risk.   Register for the upcoming 3 Day Level 400 Microsoft SQL Server 2008 and SQL Server 2005 Performance Monitoring & Tuning Hands-on Workshop in London, United Kingdom during March 15-17, 2011, click here to register / Microsoft UK TechNet.These are hands-on workshops with a maximum of 12 participants and not lectures. For consulting engagements click here.   R Meyyappan [email protected] LinkedIn: http://at.linkedin.com/in/rmeyyappan  

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  • Which will give more free RAM to linux?

    - by Linda Thomas
    Trying to avoid some issues so I've been trying to learn vm. in kernel tuning but still a little confused even after googling. The lower background_ratio is the sooner the flushes? the lower dirty_ratio is the less dirty ram that is kept, right vm.dirty_ratio = 20 vm.dirty_background_ratio = 1 or vm.dirty_ratio = 60 vm.dirty_background_ratio = 20 or vm.dirty_ratio = 20 vm.dirty_background_ratio = 10 or vm.dirty_ratio = 20 vm.dirty_background_ratio = 5

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  • Benchmarking a file server

    - by Joel Coel
    I'm working on building a new file server... a simple Windows Server box with a few terabytes of disk space to share on the LAN. Pain for current hard drive prices aside :( -- I would like to get some benchmarks for this device under load compared to our old server. The old server was installed in 2005 and had 5 136GB 10K disks in RAID 5. The new server has 8 1TB disks in two RAID 10 volumes (plus a hot spare for each volume), but they're only 7.2K rpm, and of course with a much larger cache size. I'd like to get an idea of the performance expectations of the new server relative to the old. Where do I get started? I'd like to know both raw potential under different kinds of load for each server, as well an idea of what our real-world load looks like and how it will translate. Will disk load even matter, or will performance be more driven by the network connection? I could probably fumble through some disk i/o and wait counters in performance monitor, but I don't really know what to look for, which counters to watch, or for how long and when. FWIW, I'm expecting a nice improvement because of the benefits of having two different volumes and the better RAID 10 performance vs RAID 5, in spite of using slower disks... but I'd like to get an idea of how much.

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  • How can dev teams prevent slow performance in consumer apps?

    - by Crashworks
    When I previously asked what's responsible for slow software, a few answers I've received suggested it was a social and management problem: This isn't a technical problem, it's a marketing and management problem.... Utimately, the product mangers are responsible to write the specs for what the user is supposed to get. Lots of things can go wrong: The product manager fails to put button response in the spec ... The QA folks do a mediocre job of testing against the spec ... if the product management and QA staff are all asleep at the wheel, we programmers can't make up for that. —Bob Murphy People work on good-size apps. As they work, performance problems creep in, just like bugs. The difference is - bugs are "bad" - they cry out "find me, and fix me". Performance problems just sit there and get worse. Programmers often think "Well, my code wouldn't have a performance problem. Rather, management needs to buy me a newer/bigger/faster machine." The fact is, if developers periodically just hunt for performance problems (which is actually very easy) they could simply clean them out. —Mike Dunlavey So, if this is a social problem, what social mechanisms can an organization put into place to avoid shipping slow software to its customers?

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  • Terminal server performance over high latency links

    - by holz
    Our datacenter and head office is currently in Brisbane, Australia, and we have a branch office in the UK. We have a private WAN with a 768k link to our UK office and the latency is at about 350ms. The terminal server performance is reeeeealy bad. Applications that don't have too much animation or any images seem to be okay. But as soon as they do, the session is almost unusable. Powerpoint and internet explorer are good examples of apps that make it run slow. And if there is an image in your email signature, outlook will hang for about 10 seconds each time a new line is inserted, while the image gets moved down a few pixels. We are currently running server 2003. I have tried Server 2008 R2 RDS, and also a third party solution called Blaze by a company called Ericom, but it is still not too much better. We currently have a 5 levels dynamic class of service with the priority in the following order. VoIP Video Terminal Services Printing Everything else When testing the terminal server performance, the link monitored using net-flows, and have plenty we of bandwidth available, so I believe that it is a latency issue rather than bandwidth. Is there anything that can be done to improve performance. Would citrix help at all?

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  • Performance monitoring on Linux/Unix

    - by ervingsb
    I run a few Windows servers and (Debian and Ubuntu) Linux and AIX servers. I would like to continously monitor performance on these systems in order to easily identify bottlenecks as well as to have an overview of the general activity on the servers. On Windows, I use Windows Performance Monitor (perfmon) for this. I set up these counters: For bottlenecks: Processor utilization : System\Processor Queue Length Memory utilization : Memory\Pages Input/Sec Disk Utilization : PhysicalDisk\Current Disk Queue Length\driveletter Network problems: Network Interface\Output Queue Length\nic name For general activity: Processor utilization : Processor\% Processor Time_Total Memory utilization : Process\Working Set_Total (or per specific process) Memory utilization : Memory\Available MBytes Disk Utilization : PhysicalDisk\Bytes/sec_Total (or per process) Network Utilization : Network Interface\Bytes Total/Sec\nic name (More information on the choice of these counters on: http://itcookbook.net/blog/windows-perfmon-top-ten-counters ) This works really well. It allows me to look in one place and identify most common bottlenecks. So my question is, how can I do something equivalent (or just very similar) on Linux servers? I have looked a bit on nmon (http://www.ibm.com/developerworks/aix/library/au-analyze_aix/) which is a free performance monitoring tool developed for AIX but also availble for Linux. However, I am not sure if nmon allows me to set up the above counters. Maybe it is because Linux and AIX does not allow monitoring these exact same measures. Is so, which ones should I choose and why? If nmon is not the tool to use for this, then what do you recommend?

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  • Linux's best filesystem to work with 10000's of files without overloading the system I/O

    - by mhambra
    Hi all. It is known that certain AMD64 Linuxes are subject of being unresponsive under heavy disk I/O (see Gentoo forums: AMD64 system slow/unresponsive during disk access (Part 2)), unfortunately have such one. I want to put /var/tmp/portage and /usr/portage trees to a separate partition, but what FS to choose for it? Requirements: * for journaling, performance is preffered over safe data read/write operations * optimized to read/write 10000 of small files Candidates: * ext2 without any journaling * BtrFS In Phoronix tests, BtrFS had demonstrated a good random access performance (fat better than XFS thereby it may be less CPU-aggressive). However, unpacking operation seems to be faster with XFS there, but it was tested that unpacking kernel tree to XFS makes my system to react slower for 51% disregard of any renice'd processes and/or schedulers. Why no ReiserFS? Google'd this (q: reiserfs ext2 cpu): 1 Apr 2006 ... Surprisingly, the ReiserFS and the XFS used significantly more CPU to remove file tree (86% and 65%) when other FS used about 15% (Ext3 and ... Is it same now?

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  • SQL Server: One 12-drive RAID-10 array or 2 arrays of 8-drives and 4-drives

    - by ben
    Setting up a box for SQL Server 2008, which would give the best performance (heavy OLTP)? The more drives in a RAID-10 array the better performance, but will losing 4 drives to dedicate them to the transaction logs give us more performance. 12-drives in RAID-10 plus one hot spare. OR 8-drives in RAID-10 for database and 4-drives RAID-10 for transaction logs plus 2 hot spares (one for each array). We have 14-drive slots to work with and it's an older PowerVault that doesn't support global hot spares.

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  • Oracle Magazine - Deriving and Sharing Business Intelligence Metadata

    - by David Allan
    There is a new Oracle Magazine article titled 'Deriving and Sharing Business Intelligence Metadata' from Oracle ACE director Mark Rittman in the July/August 2010 issue that illustrates the business definitions derived and shared across OWB 11gR2 and OBIEE: http://www.oracle.com/technology/oramag/oracle/10-jul/o40bi.html Thanks to Mark for the time producing this. As for OWB would be have been useful to have had the reverse engineering capabilities from OBIEE, interesting to have had code template based support for deployment of such business definitions and powerful to use these objects (logical folders etc.) in the mapping itself.

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  • Read only array, deep copy or retrieve copies one by one? (Performance and Memory)

    - by Arthur Wulf White
    In a garbage collection based system, what is the most effective way to handle a read only array if such a structure does not exist natively in the language. Is it better to return a copy of an array or allow other classes to retrieve copies of the objects stored in the array one by one? @JustinSkiles: It is not very broad. It is performance related and can actually be answered specifically for two general cases. You only need very few items: in this situation it's more effective to retrieve copies of the objects one by one. You wish to iterate over 30% or more objects. In this cases it is superior to retrieve all the array at once. This saves on functions calls. Function calls are very expansive when compared to reading directly from an array. A good specific answer could include performance, reading from an array and reading indirectly through a function. It is a simple performance related question.

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  • Tuning Red Gate: #1 of Many

    - by Grant Fritchey
    Everyone runs into performance issues at some point. Same thing goes for Red Gate software. Some of our internal systems were running into some serious bottlenecks. It just so happens that we have this nice little SQL Server monitoring tool. What if I were to, oh, I don't know, use the monitoring tool to identify the bottlenecks, figure out the causes and then apply a fix (where possible) and then start the whole thing all over again? Just a crazy thought. OK, I was asked to. This is my first time looking through these servers, so here's how I'd go about using SQL Monitor to get a quick health check, sort of like checking the vitals on a patient. First time opening up our internal SQL Monitor instance and I was greeted with this: Oh my. Maybe I need to get our internal guys to read my blog. Anyway, I know that there are two servers where most of the load is. I'll drill down on the first. I'm selecting the server, not the instance, by clicking on the server name. That opens up the Global Overview page for the server. The information here much more applicable to the "oh my gosh, I have a problem now" type of monitoring. But, looking at this, I am seeing something immediately. There are four(4) drives on the system. The C:\ has an average read time of 16.9ms, more than double the others. Is that a problem? Not sure, but it's something I'll look at. It's write time is higher too. I'll keep drilling down, first, to the unclosed alerts on the server. Now things get interesting. SQL Monitor has a number of different types of alerts, some related to error states, others to service status, and then some related to performance. Guess what I'm seeing a bunch of right here: Long running queries and long job durations. If you check the dates, they're all recent, within the last 24 hours. If they had just been old, uncleared alerts, I wouldn't be that concerned. But with all these, all performance related, and all in the last 24 hours, yeah, I'm concerned. At this point, I could just start responding to the Alerts. If I click on one of the the Long-running query alerts, I'll get all kinds of cool data that can help me determine why the query ran long. But, I'm not in a reactive mode here yet. I'm still gathering data, trying to understand how the server works. I have the information that we're generating a lot of performance alerts, let's sock that away for the moment. Instead, I'm going to back up and look at the Global Overview for the SQL Instance. It shows all the databases on the server and their status. Then it shows a number of basic metrics about the SQL Server instance, again for that "what's happening now" view or things. Then, down at the bottom, there is the Top 10 expensive queries list: This is great stuff. And no, not because I can see the top queries for the last 5 minutes, but because I can adjust that out 3 days. Now I can see where some serious pain is occurring over the last few days. Databases have been blocked out to protect the guilty. That's it for the moment. I have enough knowledge of what's going on in the system that I can start to try to figure out why the system is running slowly. But, I want to look a little more at some historical data, to understand better how this server is behaving. More next time.

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  • Performance Tuning Tips for Apache

    Apache is one of the most successful open source projects of our times. A big advantage of this popularity is that over the years people have spent a great deal of time fine tuning the software for better performance. Read on to learn more.

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  • Performance Tuning in the Age of Big Data

    Database Administrators must now deal with large volumes of data and new forms of high-speed data analysis. If your responsibility includes performance tuning, here are the areas to focus on that will become more and more important in the age of Big Data. Total DeploymentEnjoy easy release management for your .NET apps, services, and databases with Deployment Manager. Get your free Starter edition now

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  • Tuning JVM (GC) for high responsive server application

    - by elgcom
    I am running an application server on Linux 64bit with 8 core CPUs and 6 GB memory. The server must be highly responsive. After some inspection I found that the application running on the server creates rather a huge amount of short-lived objects, and has only about 200~400 MB long-lived objects(as long as there is no memory leak) After reading http://java.sun.com/javase/technologies/hotspot/gc/gc_tuning_6.html I use these JVM options -Xms2g -Xmx2g -XX:MaxPermSize=256m -XX:NewRatio=1 -XX:+UseConcMarkSweepGC Result: the minor GC takes 0.01 ~ 0.02 sec, the major GC takes 1 ~ 3 sec the minor GC happens constantly. How can I further improve or tune the JVM? larger heap size? but will it take more time for GC? larger NewSize and MaxNewSize (for young generation)? other collector? parallel GC? is it a good idea to let major GC take place more often? and how?

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  • Performance problems when running Java desktop applications on Citrix Metaframe

    - by demetriusnunes
    We have a desktop Java application running within a Citrix Metaframe server farm and the performance, specially while starting up the app, is very unreliable. Sometimes it takes 15 seconds and sometimes it takes over a minute. It's really unpredicatable. Is there any way to optimize running Java desktop applications within Citrix Metaframe Terminal server sessions to a more reliable performance level? Are there any optimization directed specifically toward Java, such as pre-load JVMs or something like that? Any help would be greatly appreciated.

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  • Need help diagnosing network performance issues

    - by tokes
    I am currently working in a developing country as a system analyst for a government department. My area of expertise is software projects, but I've come across a few issues with the network setup in my office. (Unfortunately, being a developing country, there's not a lot of professional help available for this sort of thing.) Most recently, I am trying to diagnose a problem with slowness on the network. Our office is connected to the internet via an ADSL wireless modem/router (called Router). The modem is connected via ethernet to a switch (called Switch). The modem also acts as a wireless access point (called Wireless1), though because it is in a room at the end of the floor, it's range is limited. There are ethernet ports installed around the office. The cables of these all lead back to the same switch. In closer vicinity to the bulk of the client computers, there is another wireless router that acts as an access point for those clients (called Wireless2). That router is connected via ethernet to a wall port, and therefore to Switch. There is also a Windows server which acts as a DNS server (called DNSBox) which is located in the same room and is connected directly to Switch. ---Internet----------| Router/Wireless1 192.168.10.1 ---------------| |----|=========| DNSBox | |-------------------- 192.168.10.4 --------------------| Switch |---Other clients---- | |-------------------- |----|=========| Wireless2 ------------------| 192.168.10.198 One final thing to mention about the network setup. All clients are configured with manual IP addresses. Their router/gateway is set to the IP address of Router, and their DNS server is set to the IP address of DNSBox (with a secondary IP set to an external IP - that of our ISP's DNS server). Here are the symptoms we are experiencing: Clients connected to Wireless2 AP experience slow and unstable connections to the internet. (Slow here is defined as speeds of ~1KB/s, though ping response times seem to be as normal.) Clients connected via ethernet to Switch also experience the same slowness. Clients connected to Wireless1 AP (i.e. connecting via wireless directly to the ADSL modem) experience normal connections to the internet. Clients connected via ethernet to Router (i.e. connecting via ethernet directly to the ADSL modem) also experience normal connections to the internet. I also tried to gauge the connection performance between two machines on the network via ethernet: A file transfer between two clients who were both directly connected to Switch was the fastest; A file transfer between one client directly connected to Switch, and one client directly connected to Router (which is directly connected to Switch) performed much slower; A file transfer between two clients directly connected to Router also performed slowly. Things I have attempted to diagnose the problem: Restarted Switch -- no change. We tried unplugging ethernet jacks from Switch 4 at a time and testing the internet connection. The thought here was that perhaps a client on the network has contracted a virus, and is possibly spamming the network with traffic? (Not very technical, I know.) Unfortunately we couldn't get any significant increases in performance using this method. There were a couple of times when it seemed to be better, but then the connection speed quickly dropped back to slow/dead pace. I didn't want to unplug all jacks from Switch because I was concerned that users might be affected or that I would re-plug in the jacks incorrectly (should I even be worried about that? a port is a port on a switch, right?) I tried swapping the ethernet cable used to connect Router to Switch -- no change in performance. I tried swapping the port used on Switch for Router -- no change in performance. Anyone got any ideas on what this could be? Should I be mentioning specific brand names/models of the hardware used? Virii outbreaks are common in this country/office -- what could I be doing to figure out if a virus is at fault? If it is a virus, it doesn't seem to be generating a lot of traffic to/from the internet, because a) I can still get a good speed if I am directly connected to Router / Wireless1 and b) our ISP data usage has not risen suspiciously. Thanks for your help! Update #1 Here are the specs of some of the hardware: Switch is an Edimax ES3132RL 32-Port 10/100 Rackmount Switch Router is a D-Link DSL-G604T Update #2 I just tried unplugging everything except a laptop and Router from Switch. Speeds are still slow. I guess that means that Router / Switch are not being flooded? It seems more and more likely that the cause is something to do with the interaction between Router and Switch. However, I still can't find any useful resources on setting the LAN speed for either (and I'm not well-versed in these advanced networking configurations).

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  • Slow performance by PHP directory operations on virtual machine (Ubuntu libvirt)

    - by thonixx
    Some days ago I installed an Ubuntu server and two running virtual machines with libvirt. Everything works fine except one performance problem. Everytime when I call a PHP script with directory operations the operations are very slow and not performant. Here is an example: http://zother.white-tiger.ch/ And here you see an example without a directory operation and how fast it is: http://michaeltanner.ch/ It's all on the same virtual server. The virtual machine uses 6 cores (8 are available) and 7500 megabytes RAM (8 Gigabyte are available). The disk image format is qcow2. How can I improve the performance?

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  • Performance Alert Writing to event Log but not running program

    - by TooFat
    I followed the instructions here How to create and configure performance alerts in Windows Server 2003 to set up an alert if the available logical disk space on one of my drives goes below a certain number. I selected the option to write to the application event log and select the "run this program" option and put in the path to a script that sends me an email. If I copy the path to the script and run it everything works and I get the email. When I start the alert I can see that the limit I set is being exceeded and the logs are being written to the application log, but the email is never being sent. I have the runas user and pword set to a Domain Admin. If I make the "run this program path" to C:\Windows\System32\calc.exe" it also doesn't start up the calculator. The Performance Logs and alerts services is running as Local Admin with allow to interact with desktop. What am I doing wrong?

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  • How to troubleshoot performance issues of PHP, MySQL and generic I/O

    - by jbx
    I have a WordPress based website running on a shared hosting. Its response time is very decent (around 2s to retrieve the HTML page and 5s to load all the resources). I was planning to move it to a dedicated virtual server (Ubuntu 12.04 LTS), which should theoretically improve things and make them more consistent given its not shared. However I observed severe performance degredation, with the page taking 10seconds to be generated. I ruled out network issues by editing /etc/hosts on the server and mapping the domain to 127.0.0.1. I used the Apache load tester ab to get the HTML, so JS, CSS and images are all excluded. It still took 10 seconds. I have Zpanel installed on the server which also uses MySQL, and its pages come up quite fast (1.5s) and also phpMyAdmin. Performing some queries on the wordpress database directly through phpMyAdmin returns them quite fast too, with query times in the 10 to 30 millisecond region. Memory is also sufficient, with only 800Mb being used of the 1Gb physical memory available, so it doesn't seem to be a swap issue either. I have also installed APC to try to improve the PHP performance, but it didn't have any effect. What else should I look for? What could be causing this degradation in performance? Could it be some kind of I/O issue since I am running on a cloud based virtual server? I wish to be able to raise the issue with my provider but without showing actual data from some diagnosis I am afraid he will just blame my application. UPDATE with sar output (every second) when I did an HTTP request: 02:31:29 CPU %user %nice %system %iowait %steal %idle 02:31:30 all 0.00 0.00 0.00 0.00 0.00 100.00 02:31:31 all 2.22 0.00 2.22 0.00 0.00 95.56 02:31:32 all 41.67 0.00 6.25 0.00 2.08 50.00 02:31:33 all 86.36 0.00 13.64 0.00 0.00 0.00 02:31:34 all 75.00 0.00 25.00 0.00 0.00 0.00 02:31:35 all 93.18 0.00 6.82 0.00 0.00 0.00 02:31:36 all 90.70 0.00 9.30 0.00 0.00 0.00 02:31:37 all 71.05 0.00 0.00 0.00 0.00 28.95 02:31:38 all 14.89 0.00 10.64 0.00 2.13 72.34 02:31:39 all 2.56 0.00 0.00 0.00 0.00 97.44 02:31:40 all 0.00 0.00 0.00 0.00 0.00 100.00 02:31:41 all 0.00 0.00 0.00 0.00 0.00 100.00 My suspicion that this comes from I/O related issue is also because a caching plugin I use to reduce the amount of queries to the database, by precompiling PHP pages is actually making things worse instead of better. It seems that file access is making things worse instead.

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  • VMWare Workstation Performance

    - by tekiegreg
    Hi there, awhile ago I upgraded my laptop to Windows 7 x64 from Windows XP 32 bit edition. However not before virtualizing the physical installation and I continue to run it under VMWare Workstation today. The performance on the resulting VM is just absolutely atrocious! I've done a lot of uninstalling stuff that's not longer needed since the machine is virtual in an effort to reduce RAM, but in general the responsiveness seems sluggish. I also run the Virtual Machine on it's own separate HD that is seldom used by the host OS. I'm just hoping for some general tips in increasing VMWare performance anywhere, thoughts? EDIT: Both of the below answers were excellent starting points for me. However I did like the selected answer's strategies on disk management. I am running the Virtual Machine in a separate external hard disk, likely I'm going to have to reconfigure somehow. Thanks all!

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  • Optimizing PHP<>MySQL performance

    - by BarsMonster
    I am trying to optimize my PHP<MySQL on this test script: <? for($i=0;$i<100;$i++)//Itterations count $res.= var_dump(loadRow("select body_ru from articles where id>$i*50 limit 100")); print_r($res); ?> I have APC, and article table have an index on id. Also, all these queries are hitting query cache, so sole MySQL performance if great. But when I am using ab -c 10 -t 10 to bench this scipt, I am getting: 100 itterations: ~100req/sec (~10'000 MySQL queries per second) 5 itteration: ~200req/sec 1 itteration: ~380req/sec 0 itteration: ~580req/sec I've tried to disable persistent connections in PHP - it made it slower a bit. So, how can I make it work faster, provided that MySQL is not limiting performance here?

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