Re: db file sequential read wait

> > > A buffer
> > > cache of 1G is just ridiculous and clearly demonstrates you are just
> > > trying to throw more iron at your problems.
> >
> > So what would be a good size for the buffer cache?
> >
>
> :D
>
> Probably a size that didn't make dbwr work overtime to do a checkpoint...
> I'd look at how many dbwriters this thing has. Async write
> or no async write, a 1G buffer cache ain't gonna be
> flushed easy. Regardless of it being excessive or not, which
> is a different problem.

But before anyone says anything about a particular parameter being too high or too low, shouldn't one know more about the data and the data access patterns? And that's the point I'm trying to make. You immediately assumed that I need to flush a 1GB buffer cache often. Maybe the data rarely changes so there are very few dirty buffers to write. I currently have a system like that. The database is 6TB in size and growing constantly (should be over 10TB in the next 4-5 months, and over 20TB in the next year). And 97%-99% of the data is static. So is a 1GB buffer cache too big in my case, or just plain ridiculous? Does this clearly demonstrate that I don't understand how things work?

If there was only one correct value, then these wouldn't be parameters, they'd be fixed. IMO, if one is going to say that a parameter value of XX is wrong, then one should be able to say what that correct value is. Otherwise, it is just generalities and assumptions, all of which *could* end the DBA in a bad position.

Cheers!! ;)
Brian

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Brian Peasland
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