How much free space for optimal performance?

[klokh]

I've read some times that it's usually recommended to use only up to 80% of the partition space for optimal performance (I suspect this applies to ext3).

Does anyone have some link that explain this better? Also would that be different with ext4?

Thanks.

[coopstah13]

I've never heard of this, it doesn't make much sense to me personally. I have disks filled up beyond that with no issue.

[reed9]

I've seen this 80% number before.

Here is an explanation. Can't say I know enough to gauge how accurate it is.
Why doesn't Linux need defragmenting?

[klokh]

Thanks for the link, reed. What my patience would allow me to capture is that it's best to keep different file handling usages separated, something that I had somewhat intuited.
And in my modest domestic usage, keeping all data separate from the system is a basic prevention measure from degrading the storage system.