Re: Async I/O

Hi Opus,

All I can say about it is since it is not a supported config, the behavior is UNKNOWN. It is unsafe at best to use async I/O with JFS on HP-UX 10.20. I don't believe you will suffer in terms of performance because I don't believe you get any gain to begin with.

I also noticed there are some discussions about how your data integrity will suffer when using async I/O. It is not true. To put it simply without going into details, all DBMSs today are designed to take advantage of OS level kernelized async I/O for better performance without compromising data integrity.

I will also clarify one point. JFS is a "lite" version of VxFS. The full function VxFS on HP is called OnlineJFS.

David Lai
VERITAS Software

opus wrote:

> Hi David, and thanks for responding ....
>
> So it doesn't work at all or would I get some sorta error message or
> it (as in the next reply) a matter of ensuring data integrity
> and that could be a potential problem. So far, I've had no
> problem but then... There's no way we're going to 11.0 anytime
> soon I doubt. So you recommend turning it off period then? Will
> I see some preformance degredation in disk writes or nothing
> as it doesn't really work?
>
> thanks again....
>
> David Lai wrote:
> >
> > JFS is the name for VERITAS File System (VxFS) on HP. Indeed it
> > does not support async I/O on 10.20. So you should not be using
> > async I/O right now. In a few month we are releasing
> > the VERITAS Storage Edition for Oracle on 11.0. This product
> > includes VxFS 3.3 that allows async I/O on files (with the VERITAS
> > Quick I/O driver). As a matter of fact, these Quick I/O files behave
> > and perform just like raw devices. On Solaris we have seen over 100%
> > performance improvements over traditional cooked files for TPCC
> > type workloads. We expect the same on HP as well.
> >
> > -- David Lai
> > VERITAS Software
> >
> > opus wrote:
> >
> > > Hello all,
> > >
> > > I'm running 7.3.4 on HP 10.20 and I've enabled async I/O in the kernel
> > > and in the init file. someone in Oracle support said to do that many
> > > moons ago even though it says only use async i/o with raw device files.
> > > I use JFS files. Now someone else from Oracle support sends me FAQ
> > > saying I shouldn't use asyn I/O with JFS but there's no reason as to
> > > what can happen if you do. So far been running like this for quite
> > > awhile. Any thoughts?
> > >
> > > I've also been running an Oracle 8.0.3 instance using async i/o (it
> > > defaults to that outta the box fer gawd's sake - all ya gotta do is set
> > > it up in Unix) for awhile as well.
> > >
> > > Reply to the newsgroup please, and thanks if anyone knows..
> > >
Received on Mon Mar 22 1999 - 16:55:18 CST