Blocks Vs. Sectors Vs. Physical Extents

layer8problems

I'm having a hard time figuring out if I'm dealing with apples and oranges here. From what I've read it sounds as if physical extents are synonymous with blocks....am I on the right track here? I just want to get it right before I commit it to memory.


Here are a couple of my sources:

1)
From (http://wiki.linuxquestions.org/wiki/Physical_extent )
The physical extent in LVM is the blocksize that physical volumes are using. The default physical extent is 4MB but can range from 8kB up to 16GB (using powers of 2). Logical volumes are made up from logical extents having the same size as the physical extents.

2)
From (Intro to Extents | Linux.org )
Extents are contiguous blocks on the hard disk that are used to keep files close together and prevent fragmentation.





Thank you.

Verities

A very simplistic explanation of very complicated technology:

When data is stored in volumes, it is stored in blocks. Blocks are sequential bits that are the lowest level of data on a drive. Block sizes are basically what physical extents are, just using Linux terminology. This has to do with how data is stored and read. I suggest reading about the differences between file storage and block storage to get a better understanding. I didn't really see any question about sectors, but they are locations on a physical disk, where data is stored.