Re: /dev/async (841 Views)
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Occasional Advisor
Posts: 17
Registered: ‎04-16-2013
Message 1 of 10 (936 Views)

/dev/async

[ Edited ]

what is the use of /dev/async file.

 

 

P.S. This thread has been moved from HP-UX > System Administration to databases - Hp forum moderator

 

 

Frequent Advisor
Posts: 50
Registered: ‎06-25-2012
Message 2 of 10 (928 Views)

Re: /dev/async

It is used for oracle database for async communication.
Frequent Advisor
Posts: 50
Registered: ‎06-25-2012
Message 3 of 10 (927 Views)

Re: /dev/async

 

More:

 

C.4 Asynchronous Input-Output

The asynchronous Input-Output pseudo-driver on HP-UX enables Oracle Database to perform Input-Output to raw disk partitions using an asynchronous method, resulting in less Input-Output overhead and higher throughput. You can use the asynchronous Input-Output pseudo-driver on both HP-UX servers and workstations.

This section contains the following topics:

Occasional Advisor
Posts: 17
Registered: ‎04-16-2013
Message 4 of 10 (923 Views)

Re: /dev/async

>>The asynchronous Input-Output pseudo-driver on HP-UX enables Oracle Database to perform Input-Output to raw disk

 

but we are not using any raw file system.

 

but today we got infomation from DBA that trace files are getting generated abnormally.

 

oracle version 9.2 and hp -ux version  : v2.

 

1.what could be the reason for trace file getting generated in more numbers ?

 

2.if i am not using any raw disk,why this file is existing ? can I delete it ?

Honored Contributor
Posts: 13,876
Registered: ‎06-21-2000
Message 5 of 10 (920 Views)

Re: /dev/async

1) Has the DBA looked at the trace files and the alert log?  It is the DBAs responsibility to figure this out initially.  It IS the database that is generating these after all.

 

2) There is no harm in this file existing on the system even if it is not in use.  I would not recommend deleting it.

Occasional Advisor
Posts: 17
Registered: ‎04-16-2013
Message 6 of 10 (915 Views)

Re: /dev/async

DBA has told us that they get below information in Ioctl ASYNC_CONFIG error, errno = 1

 

and

 

1.they are asking us to change the permission for /dev/async to 660.

 

currently permission is 666 and owner is bin:bin.

 

2.i have tested in test servers and changed /dev/async permission to 660 and after running insf -e ,permission get changed to 666.

 

what is the reason after updating with  insf -e,permission for /dev/async is getting changed automatically.

 

 

 

Honored Contributor
Posts: 13,876
Registered: ‎06-21-2000
Message 7 of 10 (910 Views)

Re: /dev/async

The changing of permissions of device files is a function of 'insf -e'.   Any time you run it, it will put the permissions of all device files back to their default values.

 

I do not recommend running 'insf -e'.  If you need to add new device files you should use one of the other options so you affect only specific device files and not everything.

Honored Contributor
Posts: 5,684
Registered: ‎08-05-2000
Message 8 of 10 (892 Views)

Re: /dev/async

One would assume that your DBAs have been looking at Oracle support articles 1380006.1 or 302801.1 - but not very well...

 

setting /dev/async to 660 is just the first part of the task, they also have to:

 

(1) # /usr/sbin/setprivgrp dba MLOCK
(2) # vi /etc/privgroup
-- This should contain dba MLOCK RTSCHED RTPRIO
(3) # cat /etc/privgroup
dba MLOCK RTSCHED RTPRIO

 

And presumably restart the database...

 

What the Oracle article doesn't say is that actually the message is harmless, and also /dev/async remaining at 666 doesn't cause any problems either


HTH

Duncan
Honored Contributor
Posts: 5,684
Registered: ‎08-05-2000
Message 9 of 10 (890 Views)

Re: /dev/async

... also that actually this is an Oracle bug in 9.2 where Oracle ignores the parameters:

 

disk_asynch_io=FALSE

filesystemio_options=none

 

in the init.ora file - this is fixed in 10.2 - you'll have to ask Oracle why they never back-ported the fix to 9.2...


HTH

Duncan
Highlighted
Trusted Contributor
Posts: 564
Registered: ‎04-10-2000
Message 10 of 10 (841 Views)

Re: /dev/async

I have seen this same problem with running 11G database on HPUX. Did all the steps indicated to fix the issue, but trace files are still generated continually with the same errors. Though they may be harmless - there is some overhead in generating 50000 trace files a day.

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