How to choose a web server?
I have a website and it has good traffic.
But the problem is that the database gets over thousands hit per seconds so I would like to get suggestions from you guys.
The server is capable of handling much traffic but MariaDB service gets off so What should I do?
I was thinking to use remote databases and a CDN server for contents.
Current server + Database server + CDN Server.
Does anyone have a better suggestion that will help me to get rid of the problem and also reduce the cost of CDN/database servers??
[Sorry for my grammatical mistakes]
but MariaDB service gets off so
I have no idea what this means.
I was thinking to use remote databases and a CDN server for contents
If you are serving content directly from your database then you will have performance problems. However using a CDN is only going to help if:
A large part of your customer base has a long RTT to your server
You have already optimized the caching of your content
If 1 is not the case, then you'll get as much benefit running your own cache. If 2 is the case then you're either going to have to fix your caching or enhance your database capacity.
gets over thousands hit per seconds
So what? Depending on the queries and the hardware, that might be a a constraint on your service performance. It might not. Tuning your DBMS and queries might help.
Readonly Slaves can be used to provide 'infinite' read scaling.
Turn on the slowlog, etc, to find the 'worst' queries to improve on. See http://mysql.rjweb.org/doc.php/mysql_analysis#slow_queries_and_slowlog
Galera Clustering may provide a small amount of write scaling.
Combining queries may help some.
Related
This may seem like an obvious question but we have a PHP/MySQL app that runs on Windows 2008 server. The server has about 10 different sites running from it in total. Admin options on the site in question allow an administrator to run reports (through the site) which are huge and can take about 10mins in some cases. These reports are huge mysql queries that display the data on screen. When these reports are running the entire site goes slow for all users. So my questions are:
Is there a simple way to allocate server resources so if a (website) administrator runs reports, other users can still access the site without performance issues?
Even though running the report kills the website for all users of that site, it doesn't affect other sites on the same server. Why is that?
As mentioned, the report can take about 10 minutes to generate - is
it bad practice to make these kinds of reports available on the
website? Would these typically be generated by overnight scheduled tasks?
Many thanks in advance.
The load your putting on the server will most likely have nothing to do with the applications but the mysql table that you are probably slamming. Most people get around this by generating reports in down time or using mysql replication to have a second database which is used purely for reporting.
I recommend trying to get some server monitoring to see what is actually going on. I think Newrelic just released windows versions of its platform and you can try it out for free for 30 days i think.
There's the LOW_PRIORITY flag, but I'm not sure whether that would have any positive effect, since it's most likely a table / row locking issue that you're experiencing. You can get an idea of what's going on by using the SHOW PROCESSLIST; query.
If other websites run fine, it's even more likely that this is due to database locks (causing your web processes to wait for the lock to get released).
Lastly, it's always advisable to run big reporting queries overnight (or when the server load is minimal). Having a read replicated slave would also help.
I strongly suggest you install a replicated MySQL server, then running large administrator queries (SELECT only naturally) on it, to avoid the burden of having your website blocked!
If there's not too much transaction per second, you could even run the replica on a desktop computer remotely from your production server, and thus have a backup off-site of your DB!
Are 100% sure you have added all necessary indexes?
You need to have a insanely large website to have this kinds of problems unless you are missing indexes.
Make sure you have the right indexing and make sure you do not have connection fields of varchar, not very fast.
I have a database with quite a few large tables and millions of records that is working 24/7.
Has loads of activity and automated services processing it without issues due to proper indexing.
Im having a really hard time trying to go down the RIGHT road in a project.
I'm a one man band with a tight budget.
2 dedicated servers
MySQL 5 / php5
I'm using server 1 to consume a lot of data from various feeds. The server/software is running 24/7 generating a huge database.
Server 2 - holds a copy
Of the database with a web frontend
I don't have any experience of MySQL replication. I've been researching and from what I can tell the slaves are updated right after the master.
I want to have a very speedy website so that's why the processing is done on server 1, whilst sever 2 simply selects data.
If MySQL replication is mimicking server 1 then surely this is going slow down server 2 and have the opposite of the desired effect.
What I thought might best suit this scenario is to write a script to automate the process.
Server 2 has 2 databases. One for live one for processing.
The script ascertains which database is live and instead uses the other one.
It's drops any tables in it.
The script dumps the database from server 1.
Installs it on server 2's newly emptied database.
The script changes the websites config file to utilise the new database.
The process can be repeated over and over.
Whilst the database install will be large it can happen its entirety at night and should mean no down time.
Is this better than doing MySQL replication ?
I would welcome advice.
Its hard to believe that a database dump/load cycle would be faster than replication. Especially row-based (non-query) replication. Replication can be lagged (by running SLAVE STOP SQL_THREAD on the slave) if you don't want it during peak times (but of course you must have sufficient non-peak times to catch up). (Remember that MySQL has three replication modes: statement, row, and mixed. Statement-based does the exact same update load on the slaves, row-based just sends the rows that changed, and should be fairly cheap CPU-wise)
Either all your slaves are fast enough to apply changes, and still have plenty of I/O bandwidth and CPU time to handle SELECTs, or no number of slaves will help. Its possible some other method (e.g., direct copying of data files) might be faster, but more fragile, and really you're talking some relatively minor gains. If you can't handle the update load, your choice with MySQL is to shard (split so each server is only responsible for part of the data) or buy faster hardware.
But ultimately, this is all taking shots in the dark. You can fairly easily change from replication, to rsync, to some insane scheme involving drbd, to whatever, that really only affects your database layer, maybe only the database itself. You need actual benchmarks—actual data—to make decisions like this. I will tell you that as a general rule, properly-designed large OLTP databases run out of I/O bandwidth first.
I'd suggest start with what's easy. And that'd be a single database server, or built-in replication. Keep in mind that sharding may be necessary at some point.
Actually, there is probably one question you want to answer fairly early: Do you really want to go with MySQL? Consider PostgreSQL.
A high volume of inserts can most certainly impact front end performance, but the answer for your scenario depends on very specifically how your processing engine impacts resources. There are certain combinations of settings that will allow high performance on selects while inserting data constantly. It depends on your specific duty cycle, storage engine, indexing scheme, etc.
You start by thoroughly understanding table locking http://dev.mysql.com/doc/refman/5.0/en/table-locking.html This is a must!
Then you can explore features like INSERT DELAYED http://dev.mysql.com/doc/refman/5.0/en/insert-delayed.html
And optimize your indices (as few as possible) to reduce the impact of each insert http://dev.mysql.com/doc/refman/5.0/en/insert-speed.html
Since it sounds like your requirements are driven by lots of data growth (inserts), if you can't get the performance you need from a single instance, replication probably won't help. In which case you should go for the nightly load scenario.
We have a similar use case, and we do nightly batch loads, with replication for backup/failover purposes only.
You say "If MySQL replication is mimicking server 1 then surely this is going slow down server 2 and have the opposite of the desired effect."
I don't think this is going to slow down the server. Have you tried it and measured any performance difference? I really think this is the best way to go for you, unless you clearly measure a performance impact because of the replication.
You really haven't provided enough info on what you're aiming to do, but here's my best understanding: server1 is fetching data (using bandwidth) and processing it in some way, (using processing power and I/O); server2 is serving live info to users that is based on the post-processed data. Availability for server2 is more important than for server1, and a problem on server1 should not affect server2's operations.
If the there's a significant difference between the raw data that server1 is fetching and the 'finished' data for use on server2, perhaps with some temporary data being produced along the way, just have server1 do its work, and use some kind of a script to periodically bring post-processed data from server1 to server2. Perhaps post-processed data is smaller than the raw stuff that server1 is working on?
If server1 is not really doing much processing, just fetching of data and insertion into db, then replication might be reasonable way to move data from #1 to #2.
An in-between approach would be to only replicate certain post-processed tables, so server1 can do its work in other tables in mysql, and when the final product is being inserted into the replicated table, it will automatically appear on server2.
Have fun.
We have 2 applications: web-based (PHP) and Desktop (VB) sharing the same database (Hostgator). Our web app has a fast access to the database (it's localhost). Our desktop application suffers with slow access and frequent timeouts.
What's the best approach to this kind of issue? Should we share a database? Are there any other solution.
Thanks
Some possible solutions:
Get a faster DB server
Move your database to a server that is closer to the desktop(s)
Host your webserver/DB at the location of the desktop(s)
Have two DBs, the current one that is local to the webserver and a second one that is local to the desktop(s) and set the second up as a slave to the first. You would have to consider if the desktop(s) write to the DB in this scenario. This option is probably not a good one unless the desktop(s) are read-only and aren't worried about possibly out-of-date data. This could potentially work if the desktop(s) read a lot but write less frequently.
There is no problem to "share" a DB. Have you checked the server load and the connection stability?
AFAIK, I dont suppose, this could be a problem. Because, web or desktop, both access the database with MySQL server, so it mustn't be giving mixed performance results.
The problem is probably not that it's shared; rather, it's probably the network that the data is going over. There are very few circumstances in which it's faster to use a network connection than localhost for accessing MySQL data, so you can't expect the same performance from both.
However, you should be able to get a fairly fast and reliable db connection over a good network. If you're moving huge amounts of data, you may have to employ some sort of caching. But if the issues are happening even on moderately-sized queries, you may have to bring that issue to your hosting company for troubleshooting. Many shared hosts are not optimized for remote DB hosting (most sites don't need/use/want it), so if they can't accomodate it, you may have to move to a host that will meet your needs.
The site I am developing in php makes many MySQL database requests per page viewed. Albeit many are small requests with properly designed index's. I do not know if it will be worth while to develop a cache script for these pages.
Are file I/O generally faster than database requests? Does this depend on the server? Is there a way to test how many of each your server can handle?
One of the pages checks the database for a filename, then checks the server to see if it exists, then decides what to display. This I would assume would benefit from a cached page view?
Also if there is any other information on this topic that you could forward me to that would be greatly appreciated.
If you're doing read-heavy access (looking up filenames, etc) you might benefit from memcached. You could store the "hottest" (most recently created, recently used, depending on your app) data in memory, then only query the DB (and possibly files) when the cache misses. Memory access is far, far faster than database or files.
If you need write-heavy access, a database is the way to go. If you're using MySQL, use InnoDB tables, or another engine that supports row-level locking. That will avoid people blocking while someone else writes (or worse, writing anyway).
But ultimately, it depends on the data.
It depends on how the data is structured, how much there is and how often it changes.
If you've got relatively small amounts, of relatively static data with relatively simple relationships - then flat files are the right tool for the job.
Relational databases come into their own when the connections between the data are more complex. For basic 'look up tables' they can be a bit overkill.
But, if the data is constantly changing, then it can be easier to just use a database rather than handle the configuration management by hand - and for large amounts of data, with flat files you've got the additional problem of how do you find the one bit that you need, efficiently.
This really depends on many factors. If you have a fast database with much data cached in the RAM or a fast RAID system, chances are bad, that you will gain much from simple file system caching on the web server. Also think about scalibility. Under high workload a simple caching mechanism might easily become a bottle neck while a database is well designed to handle high work loads.
If there are not so much requests and you (or the operating system) is able to keep the cache in RAM, you might be able to gain some performance. But now the question arises, if it is realy neccessary to perform caching under low work load.
From plain performance perspective, it is wiser to tune the database server and not complicate the data access logic with intermediate file caches. A good database server would do the caching on its own if the results are cacheable. (I'm not sure what is teh case with mysql).
If you have performance problems, you should profile the pages to see the real bottlenecks. Even when you are -like me- a fan of the optimized codes, putting a stronger/more hardware into the equation is cheaper on the long run.
If you still need to use caches, consider using an existing solution, like memcached.
We are working on a website for a client that (for once) is expected to get a fair amount of traffic on day one. There are press releases, people are blogging about it, etc. I am a little concerned that we're going to fall flat on our face on day one. What are the main things you would look at to ensure (in advance without real traffic data) that you can stay standing after a big launch?
Details: This is a L/A/M/PHP stack, using an internally developed MVC framework. This is currently being launched on one server, with Apache and MySQL both on it, but we can break that up if need be.
We are already installing Memcached and doing as much PHP-level caching as we can think of. Some of the pages are rather query intensive, and we are using Smarty as our template engine. Keep in mind there is no time to change any of these major aspects--this is the just the setup. What sorts of things should we watch out for?
Measure first, and then optimize. Have you done any load testing? Where are the bottlenecks?
Once you know your bottlenecks then you can intelligently decide if you need additional database boxes or web boxes. Right now you'd just be guessing.
Also, how does your load testing results compare against your expected traffic? Can you handle two times the expected traffic? Five times? How easy/fast can you acquire and release extra hardware? I'm sure the business requirement is to not fail during launch, so make sure you have lots of capacity available. You can always release it afterwards when the load has stabilized and you know what you need.
I would at least factor out all static content. Set up another vhost somewhere else and load all the graphics, CSS, and JavaScript onto it. You can buy some extra cycles, offloading the serving of that type of content. If you're really concerned, you can signup and use a content distribution service. There are lots now similar to Akamai and quite cheap.
Another idea might be to utilize Apache mod_proxy to keep the generated page output for a specific amount of time. APC would also be quite usable... You could employ output buffering capture + the last modified time of related data on the page, and use the APC cached version. If the page isn't valid any more, you regenerate and store in APC again.
Good luck. It'll be a learning experience!
Have a beta period where you allow in as many users as you can handle, measure your site's performance, and work out bugs before you go live.
You can either control the number of users explicitly in a private beta, or a Google-style semi-public beta where each user has a number of referrals that they can offer to their friends.
To prepare or handle a spike (or peak) performance, I would first determine whether you are ready through some simple performance testing with something like jmeter.
It is easy to set up and get started and will give you early metrics whether you will handle an expected peak load.
However, given your time constraints, other steps to take would be to prepare static versions of content that will attract the highest attention (such as press releases, if your launch day). Also ensure that you are making the best use of client-side caching (one fewer request to your server can make all the difference). The web is already designed for extremely high scalability and effective use content caching is your best friend in these situations.
There is an excellent podcast on high scalability on software engineering radio on the design of the new Guardian website when things calm down.
Good luck on the launch.
I'd, personally, do a few things
1) Put in some sort of load balancer/database replication system
This means that you can have your service spread across multiple servers. Can't afford to have more than one server permanently? Use Amazon E3 - It's good for putting in place for things like this (switch on a few more servers to handle the load)
2) Code in some "High Load" restrictions
For example, if your searching is inefficient - switch it off when load gets to a certain level. "Sorry, we're busy, try again later for searching"
3) Load test... Use something like ApacheBench to stress test your servers.
4) Personally, I think that switching "Keep-Alive" Connections off is better. It may slightly reduce overall performance, but - it means that instead of having something where the site works well for a few people, and the others get timeouts, everyone gets inconsistent service, if it gets to that level
Linux Format did a good article on "How to survive a slashdotting"... which I've found useful in the past. It's available online as a PDF
Basic first steps to harden your site for high traffic.
Use a low-cost tool like https://browsermob.com/ to load-test your site. At a minimum, you should be looking at 100K unique visitors per hour. If you get an ad off of the MSN home page, look to be able to handle 500K unique visitors per hour.
Move all static graphic/video content to a CDN. Edgecast and Amazon are two excellent choices.
Use Jet Profiler to profile your MySQL server to analyze any slow performing queries. Minor changes can have huge benefits.
Look into using Varnish - it's a caching reverse proxy server (like Squid, but much more single purpose).
I've run some pretty big sites behind it, and it seemed to work really well.