On Wed, Mar 15, 2017 at 09:36:24AM -0400, Stephen Ulmer wrote:
> What’s the average file size? Every file that is less than *about* 3.5K will 
> wind up in the (4k) inode itself.

average file size is about 4MB. 

> Also check the HW sector size of the SSDs (many are 4K now). If that’s the 
> case, you’ll actually be much more efficient from an access point of view 
> with 4K inodes.

HW sector size reported by disk array is 512B. SSD itself uses 4k though,
however, Linux thinks it is only 512B. 

> If you don’ t have 1PB of data yet (or won’t in the next year or so), you can 
> always expand the system pool with more SSDs in the future.

I cannot. I don't have free HW slots.

> It’s not scary to pick another size — it works just fine, but you’re about to 
> create a filesystem that will be a pain in the rear to change. It will take a 
> long time to move/backfill even a few hundred TB of data if you change you 
> mind later. You’ll definitely give up (possibly future) features by choosing 
> not 4K, but you’ve got the flexibility to do so. :)

But at least I will have space to store metadata :)

-- 
Lukáš Hejtmánek
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