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тАО01-18-2002 11:08 AM
тАО01-18-2002 11:08 AM
Solved! Go to Solution.
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тАО01-18-2002 11:20 AM
тАО01-18-2002 11:20 AM
Re: Kernel tune - max_async_ports
max_async_ports is a kernel parameter. Here is the detail on the same,
http://docs.hp.com//hpux/onlinedocs/os/KCparam.MaxAsyncPorts.html
Here is the detail on all the kernel parameters.
http://docs.hp.com//hpux/onlinedocs/os/KCparams.OverviewAll.html
Hope this helps.
Regds
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тАО01-18-2002 11:27 AM
тАО01-18-2002 11:27 AM
Re: Kernel tune - max_async_ports
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тАО01-18-2002 11:28 AM
тАО01-18-2002 11:28 AM
Re: Kernel tune - max_async_ports
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тАО01-18-2002 11:32 AM
тАО01-18-2002 11:32 AM
Re: Kernel tune - max_async_ports
The max_async_ports parameter limits the number of
processes that can open /dev/async concurrently.
As a result, the maximum is nproc, which is the
limit on the number of processes that can run on
your system at any given time.
There is no performance issue associated with
increasing this parameter.
The default is as you know 50 which on all my servers is fine _(universe) I an not sure about other databases
I would change it back to its default value - 50. Unless your database requires something different.
Paula
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тАО01-18-2002 11:39 AM
тАО01-18-2002 11:39 AM
Re: Kernel tune - max_async_ports
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тАО01-19-2002 09:38 AM
тАО01-19-2002 09:38 AM
Re: Kernel tune - max_async_ports
If you are running Oracale have a look at this.
If not what are you running on your server.
Paula
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тАО01-19-2002 09:41 AM
тАО01-19-2002 09:41 AM
SolutionThis might also help:-
2.0 Configuring asynchronous i/o
================================
aio requires configuration of both Oracle and HP-UX
2.1 HP-UX Configuration
-----------------------
a. create the /dev/async character device
% /sbin/mknod /dev/async c 101 0x0
% chown oracle:dba /dev/async
% chmod 660 /dev/async
b. configure the async driver in the kernel
Using SAM
-> Kernel Configuration
-> Drivers
-> the driver is called 'asyncdsk'
Generate new kernel
Reboot
c. set max_async_ports
Using SAM
-> Kernel Configuration
-> Configurable Parameters
-> max_async_ports
max_async_ports limits the maximum number of processes that can concurrently
use /dev/async. Set this parameter to the sum of
'processes' from init.ora + number of background processes
The background processes started at instance startup will open /dev/async
twice.
If max_async_ports is reached, subsequent processes will use synchronous i/o.
Paula
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тАО01-19-2002 04:37 PM
тАО01-19-2002 04:37 PM
Re: Kernel tune - max_async_ports
According to the Oracle 8.0.4 release notes (http://otn.oracle.co.kr/docs/oracle78/hp/server.804/A59370_01/relnote.htm),
================================================
max_async_ports parameter
max_async_ports is a configurable HP-UX kernel parameter that controls the maximum number of processes that can open /dev/async simultaneously.
During a benchmark, some shadow processes failed to open the async driver with error EBUSY. This error is caused when the async driver has already opened the number of processes specified by this parameter.
An error in opening the async driver can have performance implications on a machine with a large number of shadow processes or many parallel query slaves doing async I/O.
To avoid this error, customers should estimate the highest likely number of processes that /dev/async may run and set max_async_ports to this value.
Note that Oracle does not flag this error in the alert.log file or the trace files.
================================================
You can use Glance to identify the processes performing async I/O on your system. From there, you can perhaps give a more reliable estimate of the value you need to set max_async_ports to.
If you don't have Glance, you can use lsof to perform a check on the processes using /dev/async.
You can download lsof from one of the HP Porting and Archive Centre:
http://hpux.asknet.de/hppd/hpux/Sysadmin/lsof-4.55/
So, first try assign a huge number (eg. 2000), then perform an lsof to identify the number of processes using /dev/async (eg. lsof |grep /dev/async).
Hope this helps. Regards.
Steven Sim Kok Leong
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тАО01-21-2002 07:03 AM
тАО01-21-2002 07:03 AM
Re: Kernel tune - max_async_ports
Thanks for your insight.