Re: async i/o via nfs?

"Volker Hetzer" <volker.hetzer_at_ieee.org> wrote in message news:<bgra0h$j3$1_at_news.fujitsu-siemens.com>...

> Of course it doesn't. What I was interested in knowing was wheather the db
> in async mode *tolerates* the nfs for controlfiles. After all, I can't say
> "async=true-except-for-control-files", so if oracle used async i/o for
> controlfiles (and perhaps archiving logs too) and crashed when the target is
> on a nfs mount I couldn't use async i/o for datafiles either.

Well, look at it this way:

Oracle does not do some "misterious, behind the scenes" Unix call to read and write to disks. It uses the same calls you can use in a small C program yourself. Look them up in man pages. Mostly file units, read(), write(), ioctl() and a few related ones. "truss" the Oracle code if you want to get a detailed list of all Unix calls it makes. You'll see there are no undocumented or hidden calls there.

As such, async I/O is not some strange kind of I/O. It's just an option when you open a file and associate it with a file unit. If you pour through the relevant man pages in your OS, you should be able to find if it supports that flag on I/O to an nfs file system. Check the nfs man pages as well. It should all be there.

The reason you won't find any firm reply on this is that none of the people here would even remotely consider using nfs for anything related to database datafiles, control files, redo log files or indeed any db files! As simple as that.

For a variety of reasons, mostly to do with this paranoia that DBAs have that data is to be written/read to/from good ole hard disk. Not packets clashing in a thin wire. As such, the experience in using nfs will be very thin... ;D

Cheers
Nuno Souto
wizofoz2k_at_yahoo.com.au.nospam Received on Wed Aug 06 2003 - 19:38:35 CDT