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  1. #1

    Slow I/O in cloud hosting

    I'm using softlayer.com and seems like the IO is very slow (SAN).

    i've already upgraded my db cloud server to 4core CPU and 4GB RAM, but still slower than my old dedi server.

    What else can i do to improve the IO?

  2. #2
    Join Date
    Mar 2010
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    Germany
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    Feed them more money

    have you done some benchmarks or anything to go by?
    if their storage backend is overloaded you can not do anything but ask them to move you to a less oversold disk array / san toy. More RAM will only help for stuff that is already cached, but not for writes or accessing non-cached data. You can try adding memcached though.

    A good SAN Array will be a lot faster than a normal dedicated server, but if it's even slower then you might be better off with the dedi.
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  3. #3
    I already use memcache in my web server. U mean i should install memcache in mysql server instance too? will this help?

  4. #4
    Join Date
    Feb 2010
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    You should perform a benchmark first. Then maybe install memcache.
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  5. #5
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    Their disk I/O is pretty slow, it will take more than bringing it in memory. Maybe you're better off on a dedicated.
    I <3 Linux Clusters

  6. #6
    We're running facebook apps. Incoming requests are sent from Facebook developers and our server needs to respond in 20 sec or less. If not, we get an error page saying no response from app. You can test our app, http://apps.facebook.com/fantasyfone

    I was running dedicated server before moving to cloud, i didn't have this issue.

    I also noticed that when i access a php/mysql website hosted here (http://epl.fanxt.com), there's a big delay before the page appears. That delay tells it's waiting for mysql or io.

  7. #7
    btw, how do you do a benchmark test?

  8. #8
    Join Date
    Mar 2004
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    Cheshire, UK & WA, USA
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    Melwong,

    Something does appear to be a little wrong as http://tools.pingdom.com/?url=http:/...save=trueshows the server is taking 3 seconds before it begins sending data.

    This may not even be an IO problem. I'd check into you webserver setup.

  9. #9
    yeah i know about this. Any ideas how to troubleshoot this? My server admin is not available at the moment.

  10. #10
    Join Date
    Dec 2007
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    Indiana, USA
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    16,087
    I had mixed performance with SL's cloud storage when we trailed it but we did testing to determine the cause of slowness.
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  11. #11
    Mike, how did u do the testing?

  12. #12
    Join Date
    Nov 2009
    Posts
    544
    melwong;

    If epl.fanxt.com is an example of the coding expertise involved in your project, you have far greater problems than disk IO. Slow loading is one thing but that page is a testament to the fact that modern browsers will display darn near anything.

    If the PHP code used to generate this page has one tenth the problems that the HTML code has ... Well, let's just leave it at that...

    Maybe your sysadmin has it more together than your coders ... If he did he would be all over them so that probably is not the case...

    Yeah, go ahead blame your problems on a slow SAN, that will do it...

  13. #13
    can you be more specific srfreeman? What is the coding issue u see in my website?

  14. #14
    Join Date
    Nov 2009
    Posts
    544
    Hhmmm... More specific? That is hard.

    The HTML code is just bad. What part? Well first there is most everything between the < HTML > tag and the < /HTML > tag, then there is everything above the < HTML > tag (oh wait, there is nothing there?), then there is everything below the < /HTML > tag - I guess it is really just part of the code... The Google Analytics script is not even in any of the recommended places.

    Please don't take my word for it, check it against any HTML standards or even some HTML tutorials.

    You mentioned that this was a php/mysql app. If any php/mysql code was afforded the same lack of good sense that the HTML code represents, the application as a whole should have problems.

  15. #15
    Have you run any tests at the command line to check the storage response times, etc? Even a basic hdparm will give you an indication?
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  16. #16
    Join Date
    Dec 2010
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    USA
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    Try to get hold of a shared server provider or a cloud provider that uses SSDs in a raid array.

    Your disc IO will be much faster, but eswhat srfreeman as said, your code is ....well calling it messy is being nice.

  17. #17
    Join Date
    Dec 2004
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    You do not 'need' SSDs for good performance - realistically a good RAID 10 setup with SAS disks (or even many SATA disks) can perform well. It's high contention (many customers on the same array, 'competing' for I/O) that's going to cause poor performance.

    SSDs in shared environment are generally rare - though it's something that will be used more and more in specific applications. For example, it may be worthwhile to offload MySQL databases and such onto SSD, while keeping regular site content on SATA or SAS.

  18. #18
    Join Date
    Dec 2010
    Location
    USA
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    68

    SSD VS Hard Dics

    Yeah, I know you dont "need" SSDs for good performance on a server that is not over-contended. However you do need SSD if you have a lot of contention on a given server.

    Quote Originally Posted by layer0 View Post
    You do not 'need' SSDs for good performance - realistically a good RAID 10 setup with SAS disks (or even many SATA disks) can perform well. It's high contention (many customers on the same array, 'competing' for I/O) that's going to cause poor performance.

  19. #19
    Join Date
    Jan 2011
    Location
    Canada
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    If you haven't already, consider tuning the key buffer and table cache values for your mysql. It doesn't necessarily address the SAN performance issues, but at least it'll give you a bit more leeway.

  20. #20
    Join Date
    Dec 2010
    Location
    USA
    Posts
    68
    Yeah and if at all possible consider asking your host to add another disc (or even better multiple hard discs) to the RAID array.

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