Re: 2.6.9: unkillable processes during heavy IO

From: Lenar LÃhmus
Date: Mon Nov 15 2004 - 02:40:27 EST

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.


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

- on raw partions, instead of device mapper
- ext3 instead of XFS
- not using O_DIRECT

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