I'm looking into using Windows Performance Monitor to analyse server performance. I'm testing on the adventure works 2014 database on SQL Server 2014.
I want to try to Max out the CPU, Memory, disk usage (I/O) and possibly put a high amount of User activity. Then I can train myself in using windows performance monitor to take logs for performances around this area.
I know for CPU I can just run a heavy query within a while loop (maybe infinite) and that will go towards maxing it out.
I'm less sure about the other ones. I've tried queries which select from large tables (30,000 records), and are in a while loop to try and use some of the memory up. But it doesn't seem to drop the Available Mbytes left counter on performance monitor. Is this because the tables not big enough?
As for the disk usage, I imagine I may have to do some updates or inserts so that the disk is being written to. But I can't seem to get it to effect disk usage.
As for network, I can only think of opening up multiple queries and running them concurrently, but that seems a bit messy.
As a side note, I want to script it all myself. Rather than using any extra tools or pre canned apps that do it for you.
Related
We are running Dynamics GP 2010 on 2 load balanced citrix servers. For the past 3 weeks we have had severe performance hits when users are running Fixed Assets reporting.
The database is large in size, but when I run the reports locally on the SQL server, they run great. The SQL server seems to be performing adequately even when users are seeing slow performance.
Any ideas?
Just because your DB seems un-stressed, it does not mean that it is fine. It could contain other bottlenecks. Typically, if a DB server is not maxing-out its CPUs occasionally, it means there is a much bigger problem.
Standard process for troubleshooting performance problems on a data driven app go like this:
Tune DB indexes. The Tuning Wizard in SSMS is a great starting point. If you haven't tried this yet, it is a great starting point.
Check resource utilization: CPU, RAM. If your CPU is maxed-out, then consider adding/upgrading CPU or optimize code or split your tiers. If your RAM is maxed-out, then consider adding RAM or split your tiers.
Check HDD usage: if your queue length goes above 1 very often (more than once per 10 seconds), upgrade disk bandwidth or scale-out your disk (RAID, multiple MDF/LDFs, DB partitioning).
Check network bandwidth
Check for problems on your app (Dynamics) server
Shared report dictionaries are the bane of reporting in GP. they do tend to slow things down. also, modifying reports becomes impossible as somebody has it open all the time.
use local report dictionaries and have a system to keep them synced with a "master" reports.dic
I've read quite a bit about SQL Servers using SSDs performing much better than traditional hard drives. In load tests with my app in a test environment, though, I'm able to keep my test DB server (SQL 2005) pegged between 75% and 100% CPU usage without much of a strain on disk access (as far as I can tell). My data set is still pretty small; database backups are under 100 MB. The test server I'm using is not new, but is also no slouch.
So, my questions:
Is the CPU the bottleneck (as opposed to the storage) because the dataset is small and therefore fits in memory?
Will this change once the dataset grows so paging is necessary?
Approximately how big (as a percentage of system memory) does the dataset have to get before SQL Server starts paging? Or does that depend on a lot of other factors?
As the app and its dataset grows, are there other bottlenecks that will tend to crop up besides CPU, storage, and lack of proper indexes?
Yes
Yes
If you have SQL Server configured to use as much memory as it can get, probably when it exceeds the max system memory. But it's very setup dependant on what causes paging (the query that is being executed is the most prevalent cause).
I/O between the request machine and server is the only one that I can think of, and that only matters if you are retrieving large datasets. I also would not group a lack of indexes as a bottleneck, rather indexes enable better performance with regard to searching.
As long as the CPU is the bottleneck on your dedicated SQL-Server machine, you don't have to worry about disk speed (assuming nothing's wrong with the machine). SQL-Server WILL use heavy memory caching. SQL-Server has built-in strategies to perform best under a given load and available resources. Just don't worry about it!
I'm developing a project which gets some data from a hardware every 100 milliseconds. I'm using Visual Studio 2010 and C#. The data size is about 50KB in each round. The customer wants to log all the data in the database for statistical purposes.
I prefer using SQL Server 2005+ since I'm familliar with it and the project should be done in about 15 days it's a small size project.
Is this a reasonable speed for such a data size to be inserted into db? Do you suggest any generic approaches to speed up the interactions? (using sql commands, EF, other technologies which could have a positive effect on speed).
If this is way too fast for SQL Server to handle, what do you suggest I should use which:
1-has a quick learning curve.
2-could accept queries for statistical data.
3- could satisfy my speed interaction needs.
I'm thinking about System.Data.SQLite If it's a no go on SQL Server. But I don't know about the learning curve and speed enhancements.
500kb per second is nothing. I work with Sql databases that does gigabytes per second, it all depends on the hardware and server configuration underneath, but lets say you were to run this on a standard office desktop, you will be fine. Even then I would say you can start thinking about new hardware if you look at 20Mb per second or more.
Second part of your question. Since you are using c#, I suggest you use SQL 2008 and then use a table valued parameter (TVP), and then buffer the data in the application, in a dataset or datatable until you have say 10K rows, and then you call the proc to do the insert, and all you do is pass it the datatable as a parameter. This will save hundreds or thousands of ad-hoc inserts.
Hope this is clear, if not, ask an I will try to explain further.
50kB every 100 millseconds is 500kB a second. These days networks run at gigabit speeds (many megabytes per second) and hard drives can cope with hundreds of MB per second. 500kB is a tiny amount of data, so I'd be most surprised if SQL server can't handle it.
If you have a slow network connection to the server or some other problem that means it struggles to keep up, then you can try various strategies to improve things. Ideas might be:
Buffer the data locally (and/or on the server) and write it into the database with a separate thread/process. If you're not continually logging 24 hours a day, then a slow server would catch up when you finish logging. Even if you are logging continuously, this would smooth out any bumps (e.g. if your server has periods of "busy time" where it is doing so much else that it struggles to keep up with the data from your logger)
Compress the data that is going to the server so there's less data to send/store. If the packets are similar you may find you can get huge compression ratios.
If you don't need everything in each packet, strip out anything "uninteresting" from the data before uploading it.
Possibly batching the data might help - by collecting several packets and sending them all at once you might be able to minimise transmission overheads.
Just store the data directly to disk and use the database just to index the data.
... So I'd advise writing a prototype and see how much data you can chuck at your database over your network before it struggles.
I've read that it's unwise to install SQL Server and IIS on the same machine, but I haven't seen any evidence for that. Has anybody tried this, and if so, what were the results? At what point is it necessary to separate them? Is any tuning necessary? I'm concerned specifically with IIS7 and SQL Server 2008.
If somebody can provide numbers showing when it makes more sense to go to two machines, that would be most helpful.
It is unwise to run SQL Server with any other product, including another instance of SQL Server. The reason for this recommendation is the nature of of how SQL Server uses the OS resources. SQL Server runs on a user mode memory management and processor scheduling infrastructure called SQLOS. SQL Server is designed to run at peak performance and assumes that is the only server on the OS. As such the SQL OS reserves all RAM on the machine for SQL process and creates a scheduler for each CPU core and allocates tasks for all schedulers to run, utilizing all CPU it can get, when it needs it. Because SQL reserves all memory, other processes that need memory will cause SQL to see memory pressure, and the response to memory pressure will evict pages from buffer pool and compiled plans from the plan cache. And since SQL is the only server that actually leverages the memory notification API (there are rumors that the next Exchange will too), SQL is the only process that actually shrinks to give room to other processes (like leaky buggy ASP pools). This behavior is also explained in BOL: Dynamic Memory Management.
A similar pattern happens with CPU scheduling where other processes steal CPU time from the SQL schedulers. On high end systems and on Opteron machines things get worse because SQL uses NUMA locality to full advantage, but no other processes are usually not aware of NUMA and, as much as the OS can try to preserve locality of allocations, they end up allocating all over the physical RAM and reduce the overall throughput of the system as the CPUs are idling on waiting for cross-numa boundary page access. There are other things to consider too like TLB and L2 miss increase due to other processes taking up CPU cycles.
So to sum up, you can run other servers with SQL Server, but is not recommended. If you must, then make sure you isolate the two server to your best ability. Use CPU affinity masks for both SQL and IIS/ASP to isolate the two on separate cores, configure SQL to reserve less RAM so that it leaves free memory for IIS/ASP, configure your app pools to recycle aggressively to prevent application pool growth.
Yes, it is possible and many do it.
It tends to be a question of security and/or performance.
Security is questioned as your attack surface is increased on a box that has both. Perhaps not an issue for you.
Performance is questioned as now your server is serving web and DB requests. Again, perhaps not an issue in your case.
Test vs. Production....
Many may feel fine in test environments but not production....
Again, your team's call. I like my test and production environments being as similar as possible if possible but that's my preference.
It's possible, yes.
A good idea for a production environment, no.
The problem that you're going to run in to is that a SQL Server database under substantial load is, more than likely, going to be doing heavy disk I/O and have a large memory footprint. That combination is going to tie up the machine, and you're going to see a performance hit in IIS as it tries to serve up the pages.
It's unwise in certain contexts... totally wise in others.
If your machine is underutilized and won't experience heavy loads, then there is an advantage to installing the database on the same machine, because you simply won't have to transfer anything across the network.
On the other hand, if one or both of IIS or the database will be under heavy load, they will likely start to interfere, and the performance gain of dedicated hardware for each will probably outstrip the loss of having to go over the network.
Don't forget the maintenance issue...you can't reboot/patch one without nuking the other. If they are on two boxes, you could give your users a better experience, than no response from the webserver if you are maintaining the SQL box.
Not highest on the list, but should be noted.
You certainly can. You will run into performance issues if, for example, you have large user base or if there are a lot of heavy query's being run against the DB. I have worked on several sites, usually hosted at 1and1, that run IIS and SQL Server (Express!) on the same box with thousands of users (hundreds concurrent) and millions of records in poorly designed tables, accessed via poorly written stored procedures and the user experience was certainly tolerable. It all comes down to how hard you plan on hitting the server.
Are there any ways to determine what the differences in databases are that affect a SSIS package load performance ?
I've got a package which loads and does various bits of processing on ~100k records on my laptop database in about 5 minutes
Try the same package and same data on the test server, which is a reasonable box in both CPU and memory, and it's still running ... about 1 hour so far :-(
Checked the package with a small set of data, and it ran through Ok
I've had similar problems over the past few weeks, and here are several things you could consider, listed in decreasing order of importance according to what made the biggest difference for us:
Don't assume anything about the server.
We found that our production server's RAID was miscconfigured (HP sold us disks with firmware mismatches) and the disk write speed was literally a 50th of what it should be. So check out the server metrics with Perfmon.
Check that enough RAM is allocated to SQL Server. Inserts of large datasets often require use of RAM and TempDB for building indices, etc. Ensure that SQL has enough RAM that it doesn't need to swap out to Pagefile.sys.
As per the holy grail of SSIS, avoid manipulating large datasets using T-SQL statements. All T-SQL statements cause changed data to write out to the transaction log even if you use Simple Recovery Model. The only difference between Simple and Full recovery models is that Simple automatically truncates the log file after each transactions. This means that large datasets, when manipulated with T-SQL, thrash the log file, killing performance.
For large datasets, do data sorts at the source if possible. The SSIS Sort component chokes on reasonably large datasets, and the only viable alternative (nSort by Ordinal, Inc.) costs $900 for a non-transferrable per CPU license. So... if you absolutely have to a large dataset then consider loading it into a staging database as an intermediate step.
Use the SQL Server Destination if you know your package is going to run on the destination server, since it offers roughly 15% performance increase over OLE DB because it shares memory with SQL Server.
Increase the network packaet size to 32767 on your database connection managers. This allows large volumes of data to move faster from the source server/s, and can noticably improve reads on large datasets.
If using Lookup transforms, experiment with cache sizes - between using a Cache connection or Full Cache mode for smaller lookup datasets, and Partial / No Cache for larger datasets. This can free up much needed RAM.
If combining multiple large datasets, use either RAW files or a staging database to hold your transformed datasets, then combine and insert all of a table's data in a single data flow operation, and lock the destination table. Using staging tables or RAW files can also help relive table locking contention.
Last but not least, experiment with the DefaultBufferSize and DefaulBufferMaxRows properties. You'll need to monitor your package's "Buffers Spooled" performance counter using Perfmon.exe, and adjust the buffer sizes upwards until you see buffers being spooled (paged to disk), then back off a little.
Point 8 is especially important on very large datasets, since you can only achieve a minimally logged bulk insert operation if:
The destination table is empty, and
The table is locked for the duration of the load operation.
The database is in Simply / Bulk Logged recovery mode.
This means that subesquent bulk loads a table will always be fully logged, so you want to get as much data as possible into the table on the first data load.
Finally, if you can partition you destination table and then load the data into each partition in parallel, you can achieve up to 2.5 times faster load times, though this isn't usually a feasible option out in the wild.
If you've ruled out network latency, your most likely culprit (with real quantities of data) is your pipeline organisation. Specifically, what transformations you're doing along the pipeline.
Data transformations come in four flavours:
streaming (entirely in-process/in-memory)
non-blocking (but still using I/O, e.g. lookup, oledb commands)
semi-blocking (blocks a pipeline partially, but not entirely, e.g. merge join)
blocking (blocks a pipeline until it's entirely received, e.g. sort, aggregate)
If you've a few blocking transforms, that will significantly mash your performance on large datasets. Even semi-blocking, on unbalanced inputs, will block for long periods of time.
In my experience the biggest performance factor in SSIS is Network Latency. A package running locally on the server itself runs much faster than anything else on the network. Beyond that I can't think of any reasons why the speed would be drastically different. Running SQL Profiler for a few minutes may yield some clues there.
CozyRoc over at MSDN forums pointed me in the right direction ...
- used the SSMS / Management / Activity Monitor and spotted lots of TRANSACTION entries
- got me thinking, read up on the Ole Db connector and unchecked the Table Lock
- WHAM ... data loads fine :-)
Still don't understand why it works fine on my laptop d/b, and stalls on the test server ?
- I was the only person using the test d/b, so it's not as if there should have been any contention for the tables ??