Asm extent distribution

[satish]

Hi erman,

Does asm distributes extents based on disk sizes or it distributes in a round robin fashion.we would like to understand the impact of having different disk sizes in a diskgroup

We are on 12.1.0.2

Thanks for all the support.

[ErmanArslansOracleBlog]

ASM distributes file extents across all of the disks in a disk group uniformly.
You should have the similar kinds (in terms of same size and same performance) of disks in an ASM diskgroup.
If you don't do this, you will end up having an unstable environment.. Especially in performance..
This is a long story bytheway..
If I summarize it, I can say that , if you have different type of disks in ASM diskgroup, you may encounter uneven response times from the disk group.
For instance, if you have a diskgroup which has 2 small fast disks, and 2 big slow disks, then you will see that some IOs are done fast and some IOs are done slow.. (randomly)

[satish]

Thanks erman,

If you have a diskgroup which has uneven disk sizes,In this case we wanted to know will large disks have more extents and small disks have less extents?
If yes,then ASM distributes extents based on capacity right?

[ErmanArslansOracleBlog]

Yeah that's possibble. (possibly, if the smaller disks are filling their capacity.)

[satish]

Thanks for the update erman