topic Re: async_config I/O error - device files problem? in Operating System - HP-UX

async_config I/O error - device files problem?

Philip Kernohan — Wed, 26 Sep 2001 03:15:14 GMT

Howdy,

we are seeing "Ioctl async_config, errno=1" errors in an Oracle trace file once for every sqlplus session.

In /dev we have two device files with the same minor and major numbers (async and asyncdsk) - is this normal or can it cause problems? - both are 101 0x0.

There is apparently a fix for this using 'setprivgrp' but I need to assure myself that the device files are not linked to this problem.

All help/advice appreciated.

Regards,
PK

Re: async_config I/O error - device files problem?

Animesh Chakraborty — Wed, 26 Sep 2001 04:31:11 GMT

Hi,
In our server it is like this.
crw-r--r-- 1 root sys 101 0x000001 Jan 27 2000 async
crw-rw-rw- 1 bin bin 101 0x000000 Jan 26 2000 asyncdsk

They are not same

Regards
Animesh

Re: async_config I/O error - device files problem?

Animesh Chakraborty — Wed, 26 Sep 2001 07:47:43 GMT

Hi again,
Are you using raw logical volumes?If you are using raw logical volumes , consider implementing asynchronous IO.

The difference between the async i/o and the synchronous i/o is that async does
not wait for confirmation of the write before moving on to the next task. This
does increase the speed of the disk performance at the expense of robustness.
Synchronous I/O waits for acknowledgement of the write (or fail) before
continuing on. The write can have physically taken place or could be in the
buffer cache but in either case, acknowledgement has been sent. In the case of
async, no waiting.

To implement asynchronous IO on HP-UX
* add the asyncdisk Driver (Asynchronous Disk Pseudo Driver)
to the HP-UX Kernel (using SAM),

* create the device file:

# mknod /dev/async c 101 0x00000#
#=the minor number can be one of the following values:

0x000000 default
0x000001 enable immediate reporting
0x000002 flush the CPU cache after reads
0x000004 allow disks to timeout
0x000005 is a combination of 1 and 4
0x000007 is a combination of 1, 2 and 4

Note: Contact your database vendor or product vendor to determine the
correct minor number for your application.

Hope this helps
Animesh

Re: async_config I/O error - device files problem?

Carlos Fernandez Riera — Wed, 26 Sep 2001 09:06:21 GMT

You must configure setprivs

Create /etc/privgrp
MLOCK dba

run setprivgrp.

See /sbin/init.d/setpr* for correct filename.

See oracle docs also.

Re: async_config I/O error - device files problem?

John Guster — Thu, 18 Jan 2007 13:37:24 GMT

what is /dev/async and what is /dev/asyndsk? what is the difference between these 2?

Re: async_config I/O error - device files problem?

Sandman! — Thu, 18 Jan 2007 18:06:08 GMT

Most likely that is the problem since asyncdsk is the driver for implementing asynchronous I/O and it writes to the special file /dev/async. Make sure you have the asyncdsk driver in the kernel.