Re: 2.6.9: unkillable processes during heavy IO

[Lenar LÃhmus]

I had similar hanging with mysql on 64bit_debian@A64 3500+ + mysql 
4.1.5. 1GB memory.

After digging around I added "skip-concurrent-insert" to mysql conf and 
those hangs disappeared.
It might be mysql problem (not kernel) on 64bit linux.

Although my mysql processess where killable with -9.

Lenar

Brad Fitzpatrick wrote:

> We have two database servers which freeze up during heavy IO load.  The
> machines themselves are responsible, but the mysqld processes are forever
> locked, unkillable with even kill -9.  I can't restart with MySQL without
> rebooting the machines.
>
> I can reasonable rule out hardware, since this is happening in the
> same way on two identical machines.
>
> I'd like to know how I can debug this, to file a proper bug report.
>
> The hardware/software stack is:
>
>  - Dual Opteron 246, SMP kernel, w/ NUMA
>  - 9 GB of memory (4GB in one zone, 5GB in the other)
>  - MySQL, running mostly InnoDB, but some MyISAM
>  - MegaRAID raid-10
>  - device mapper
>  - XFS (used as both O_DIRECT from InnoDB and regularly from MyISAM)
>
> At this point I'm going to try changing different variables on
> different machines in order to try and isolate it, but it's a slow
> process.
>
>  - on raw partions, instead of device mapper
>  - ext3 instead of XFS
>  - not using O_DIRECT
>  

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