Re: DB_BLOCK_SIZE and Solaris block size

>
> Is it true that Solaris (7, 8, 9) has a OS block size of 64K by default

I believe that you are really up against several things:

1. filesystem block size, if you are using filesystem. This is a function of the newfs parameters (which may/may not autoadjust as a function of the device size). It is likely in the 1k-8k range.
2. vm_page_size. This is the size of virtual memory pages on the system. I'm pretty sure that this is 8k on sun systems.
3. actual emitted io size to the devices. This can range from 512b to several megabytes as a function of what is emitting the io's and how it is doing it.

>From #2, I would suggest you not go below 8k as you'll create more work for the
system to manage partial pages.

However, the true answer is "It all depends." This ultimately is going to be a function of what you are doing with oracle. Large db block sizes are good for many types of warehousing, smaller makes for better oltp performance.

• craig

> ?
>
> In this case, is it correct to sizing the DB_BLOCK_SIZE for a new
> database (8.1.7) at 64K ?
> This question because all of our databases was installed with:
> db_block_size = 8192
>
> How to check the value for the OS block size on Solaris (7,8,9) ?
>
> Thanks for your help ?
>
> Jean Berthold
>
>
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-- 



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