Disk Blocks, Oracle Blocks, Physical vs. Logical I/O

Question

Hi,
I would like to request for some clarification. Sam Alapati states the following in his book “Expert Oracle9i Database Administration:”
“The storage disks on which the Oracle blocks reside are themselves divided into disk blocks, which are areas of contiguous storage containing a certain number of bytes—for example, 4096 or 32768 bytes (4KB or 32KB, because each kilobyte has 1024 bytes). Note that if the Oracle block size is smaller than the operating system file system buffer size, you may be wasting the capacity of the operating system to read and write larger chunks of data for each I/O.”
There are several questions stemming from the above discussion:
1.     Is the “file system buffer size” the same as the size of a disk block?
2.     Is the disk block the unit of physical I/O?
3.     Does there exist such a term as “logical I/O” in Oracle’s nomenclature? With the help of my limited knowledge of database administration, what I understand from the term “logical I/O” is “reading or writing of one Oracle block,” which, in turn, requires several physical I/O’s depending on how large a multiple of the OS block size the Oracle block size is. In that case, does setting the Oracle block size to, say, 8 KB, when the OS block size is, say, 2 KB then mean that one logical I/O would involve four physical I/O’s? Please correct me if I am mistaken.
Thanks,
Karim

Answer 1

I second that.
For all questions about the very basic concepts in the world of oracle db, you should read the, erhm, yes Concepts guide (read it back and forth a couple of times, then keep revisit).
Also via the tahiti page you can search or get books from libraries of the various server products from 8i, 9i, and 10g families.