[CentOS] Optimum Block Size to use

[Chris Murphy]

On Tue, Aug 18, 2015 at 9:38 PM, Jatin Davey <jashokda at cisco.com> wrote:

> I have a few queries with respect to the block size being set in the system:
>
> 1. Is 4k the optimum block size considering the amount of writes / second
> the application performs ?
>
> 2. How do i find out the optimum block size given the application load in
> terms of reads / writes per second ?
>
> 3. If there is a better block size that i can use , Can you suggest one ?
>
> 4. What are the pros / Cons of changing the default block size ?

On x86, it's effectively fixed at 4096 bytes. There is a clustering
option in ext4 called bigalloc which isn't the same thing as block
size but might be what you're looking for if you have a lot of larger
file writes happening. But this implies CentOS 7 to get this feature.

> 5. We use ext3 as the file system for the partition which has heavy writes
> per second , Should we migrate it to ext4 ? Any pros / cons for it ?

Piles of pros, and no meaningful cons. Just use ext4 with defaults.


-- 
Chris Murphy