mysql-governor read / write limits units ?
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  1. Richard Hordern
  2. 03.02.2013
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Hello,

In the mysql-governor configuration file what are the units for :


If it is in bytes per second 100000000 => 95 MB /s
If this is correct the default value seems quite high or should I devide the value by 1000 again making it about 1MB /s ?

Thanks
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  1. 05.02.2013 02:02:23
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Shkatula Pavel Accepted Answer
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Hello,

 <limit name=\"w rite\" current=\"100000000\" short=\"90000000\" mid=\"80000000\" long=\"70000000\"/>
this is in bytes per second
this value default is used to work with minimum restrictions, you need to set limits on one\'s own
  1. 05.02.2013 04:02:24
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Richard Hordern Accepted Answer
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OK, I\'ll have to play around with the limits then. Because I\'m using SSD\'s for the database, and ramdisk for the mysql tmp folder, users very often trigger the initial current limit. I thought if this limit was 1MB per second then it was normal but if it\'s 100MB per second then maybe I\'ll have to keep a higher limit than 100MB/s for the current value so as to not block normal users.
  1. 06.02.2013 21:02:25
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steven elvisda Accepted Answer
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Hello Richard Hordern,

what is deference between configure file and dbctl. which one should I play around with?

currently, my server run with SATA 3 and it is I/O high load every 1 hour.

Best Regards,
Steve.
  1. 07.02.2013 01:02:28
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Richard Hordern Accepted Answer
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Hello Steven,

Where did you read about the file or dbctl setting ?

The first thing you need to do is determine what is causing the high load. 

Have you installed iotop ?

With iotop you should be able to determine what is causing your load.

If it's mysql then installing mysql governer should help but first you might want to make sure mysql is using enough memory, if you havn't activated any caches then you might want to start by there before installing software to limit each user.
  1. 07.02.2013 11:02:50
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steven elvisda Accepted Answer
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Hello Richard,

I read both of them. now I choose configuration file as my best choice.

yeah I use atop, iostat and iotop to check the reall high load.

current I can see that user mysql is using less CPU consumption but I/O is too high.

what should I do with this user mysql

can you have idea?

Best Regards,
  1. 07.02.2013 11:02:08
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Richard Hordern Accepted Answer
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I still don\'t know what you are talking about with the file and dbctl setting. Is this a setting in mysql governor or a mysql setting maybe ?

The first thing you need to do is tune mysql memory settings (see http://www.howtoforge.com/tuning-mysql-performance-with-mysqltuner ) then you can install mysql governor and limit each user to a max read/write speed.
  1. 07.02.2013 22:02:15
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steven elvisda Accepted Answer
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the configuration file of db_governor is /etc/container/mysql-governor.xml and command dbctl

yeah I already tune and limitation of all users for using mysql by db_governor. But the problem still met because using mysql is used very hight read/write on hard disk.

here is the line that I was capture of atop

570217     mysql   mysql     68 0.12s 0.11s    0K    4K    4K     17164K     -- -     S    3 2%     mysqld

which are
4K is I/O read
17164K is I/O write
2% is cpu usage


do you think that we have to limite this us er(mysql)?


Regards,
  1. 08.02.2013 01:02:59
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Richard Hordern Accepted Answer
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17MB/s doesn\'t seem abnormaly high for mysql, but I guess on a single hard drive raid 1 it could slow things down quite a lot !

Are you talking about limiting the mysql user in CloudLinux ? Or a specific database user using mysql governor ?

I guess if you want your customers to only host non database related content then limiting mysql could be OK. It would probably result with slow page loads for everyone on the server that uses databases.

If you have installed mysql governor then dbtop should give you some info on which user is causing the load as well as the read/write speeds your users are using.

With this info you should be able to play around with mysql governers\'s read/write limits per user.

Limiting is still slowing down, so if you don\'t want to slow down, then maybe you should concider either upgrading your server with ram or maybe a couple of SSD\'s or get a server that you would use as a dedicated mysql server (preferably running on SSD\'s or at least Raid 10).
  1. 08.02.2013 02:02:39
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steven elvisda Accepted Answer
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that is such a good idea  Richard,

in case I purchase other server that using SSD and replicate mysql from it to my current server. is it a good idea for it?
  1. 08.02.2013 02:02:55
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Richard Hordern Accepted Answer
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The whole migrating procedure will take a bit of thinking. Firstly if you\'ve got only a few accounts or only a few accounts that use up all the ressources you could simply migrate them manually to the new mysql server.

Try and get at least a Gbps connection for this server
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