Fw: VxFS threaded AIO vs. DBWR Slaves

Hi All,

On further research it would seem that threaded Async I/O is a property of Solaris, not of VxFS. And that HP-UX doesn't share that feature. (Please let me know if I'm still getting it wrong!)

Therefore, since I'm stuck with HP-UX on VxFS, I'll look at the DBWR_IO_SLAVES option.

Thanks for all who replied!

Charlotte

• Forwarded Message ---- From: Charlotte Hammond <charlottejanehammond_at_yahoo.com> To: Greg Rahn <greg_at_structureddata.org>; oracle-l_at_freelists.org Sent: Tuesday, February 26, 2008 9:24:45 PM Subject: Re: VxFS threaded AIO vs. DBWR Slaves

Hi Greg,

Thanks for the tip. Unfortunately I'm not in a position to dictate ASM at present and have to live with what I've got (at least for now!).

Somebody mentioned off-list that threaded AIO may not be a feature of VxFS on HP-UX (although I believe it is on Solaris). Can anyone confirm or refute? I'm finding it hard to get a definitive answer on this.

Assuming that threaded AIO *does* exist and that I *do* want to use it, should I just set FILESYSTEMIO_OPTIONS=SETALL and DISK_ASYNCH_IO=TRUE as if it were kernelized AIO?

Thanks You!
Charlotte

• Original Message ---- From: Greg Rahn <greg_at_structureddata.org> To: charlottejanehammond_at_yahoo.com Cc: oracle-l_at_freelists.org Sent: Monday, February 25, 2008 10:09:29 PM Subject: Re: VxFS threaded AIO vs. DBWR Slaves

I would suggest using ASM. Then you can leverage all the benefits and not have to worry about file layout.

If you use threaded async or emulate async by multiple db writers, its probably the same overhead.

On 2/25/08, Charlotte Hammond <charlottejanehammond_at_yahoo.com> wrote:
> Hi All,
>
> I'm building a 10g database on a VxFS filesystem on HP-UX. I understand this does not support kernelized asynchronous I/O but does support threaded asynchronous I/O which I believe has a significant CPU overhead. So: should I use the threaded asychronous I/O from VxFS (FILESYSTEMIO_OPTIONS=SETALL) or should I switch it off, and use multiple database writer slaves instead?
>
> My aim is targeted towards performance rather than capacity (i.e. small number of users in database).

-- 
Regards,

Greg Rahn
http://structureddata.org





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