# What is [aiod1], [aiod2], [aiod3], and [aiod4]?



## Anonymous (Apr 27, 2011)

Yesterday, I found in the mid of the list generated by *ps -axj* 4 entries named [aiod1], [aiod2], [aiod3], and [aiod4], all of them being child processes of */sbin/init --*. Using Google, I could not find any satisfactory answer on what [aoidN] is, and what to do about/with it. After restarting the system, they disappeared.

The system is running FreeBSD 8.2-RELEASE (GENERIC_IPSEC) #1, i.e. a derivate of a GENERIC kernel with IPsec enabled.

Many thanks in advance for any reply.

Best regards

Rolf


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## SirDice (Apr 27, 2011)

AIO is Asynchronous I/O. See aio(4).


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## Zare (Apr 27, 2011)

aio(4)



> The aio facility provides system calls for asynchronous I/O.  It is
> available both as a kernel option for static inclusion and as a dynamic
> kernel module.



By the way, the brackets [] entry inside ps output are kernel threads.


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## Anonymous (Apr 27, 2011)

SirDice and Zare, thank you very much for your response.

What could have triggered the start of 4 kernel aio-daemons in the mid of the day, i.e. long time after the last reboot? For what pupose? I never saw this before.


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## tingo (Apr 28, 2011)

Depends on how you have configured your machine. Samba can be configured to use AIO, for example.


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## Anonymous (Apr 28, 2011)

Torfinn, thank you very much for your reply. This brought me to checking Samba, and indeed, it created the 4 [aiodN] kernel processes, once I connected to a share.

Best regards

Rolf


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## Zare (Apr 30, 2011)

QEMU also benefits from aio


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