Re: Hardware/OS recommendations for large databases (

Alan,

On 11/23/05 2:00 PM, "Alan Stange" <stange(at)rentec(dot)com> wrote:

> Luke Lonergan wrote:
>> Why not contribute something - put up proof of your stated 8KB versus
>> 32KB page size improvement.
>
> I did observe that 32KB block sizes were a significant win "for our
> usage patterns". It might be a win for any of the following reasons:
> (* big snip *)

Though all of what you relate is interesting, it seems irrelevant to your
earlier statement here:

>> Alan Stange <stange(at)rentec(dot)com> writes:
>> If your goal is sequential IO, then one must use larger block sizes.
>> No one would use 8KB IO for achieving high sequential IO rates. Simply
>> put, read() is about the slowest way to get 8KB of data. Switching
>> to 32KB blocks reduces all the system call overhead by a large margin.
>> Larger blocks would be better still, up to the stripe size of your
>> mirror. (Of course, you're using a mirror and not raid5 if you care
>> about performance.)

And I am interested in seeing if your statement is correct. Do you have any
proof of this to share?

- Luke