Re: MySQL slow and high load with Debian Wheezy (was: [whole mail text])

[Martin Steigerwald]

Hi Andrei,

How could that KMail can answer from the subject if marked, but I strongly 
second Lisi´s notion of putting a legible text into the mail body and using a 
fine descriptive and short enough subject for the mail.

Am Donnerstag, 23. Mai 2013, 11:15:29 schrieb Andrei Hristow:
> Hi, I have a serious problem with Debian 7. The system is very slow, work
> with MySQL databases is slow and painful. On Debian 6.0.7 system is very
> fast and stable, works on ext3 and ext4 on Debian 7. I have 8 GB of RAM and
> use the AMD64 version. CPU is 2.133 Ghz Intel core 2 duo. Mainboard is
> Gigabyte GA-EP45-UD3R socket 775 Hard drive using ata_piix driveron debian
> 6 and debian 7. Where could be the problem? Be because of ext4? Or should I
> use the i386 version of Debian 7 with PAE kernel The difference in
> performance between debian 6 and debian 7 is huge! I use wine and system
> load reached 10.0 What are your tips. What is better to use. Debian 7 i386
> or Debian 7 AMD64 ? And whether it's better to ext3 or ext4

Lots of information is missing in there. What does slow mean? How do you 
notice its slow? Do you have any numbers? What is the workload? How is memory, 
cpu, disk usage and so on…

But just a rough guess:

Are you by chance using the -486 kernel? Well that will give you *one* CPU and 
I think a maximum of 1 GB of RAM (not sure about the latter).

With any current x86 hardware for 32-bit 686-pae is suitable, for 64-bit its 
amd64.

Ciao,
-- 
Martin 'Helios' Steigerwald - http://www.Lichtvoll.de
GPG: 03B0 0D6C 0040 0710 4AFA  B82F 991B EAAC A599 84C7


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Re: Re: MySQL slow and high load with Debian Wheezy (was: [whole mail text])

[Daniel Enright]

Found this thread searching for a solution to my problem (which sounds 
similar).


My solution was barrier=0 in /etc/fstab see

https://wiki.archlinux.org/index.php/Ext4

Uh, specifically my problem was that loading large mysql files took 
forever and would often end with mysql losing the connection (local 
mysql daemon). Smaller files were still slow (especially from the 
context of running unit tests that do lots of mysql queries via sql files.


iostat (apt-get install sysstat; iostat -x -d sda 5;) showed very high 
%util, but very low writes. Interestingly when I pointed the mysql 
server to store the data on slower usb mounted drives I had better 
performance.  Anyway my old workstation running squeeze gives good 
performance. Wheezy bad performance until barrier=0 was added.


Before using barrier=0 I played around with stuff such as wrapping sql 
in set autocommit =0; and commit; Also played with innodb mysql server 
settings.


But, for me barrier=0 is awesome! (Using laptop so have battery in case 
power fails...).


Daniel


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