xfs_growfs / planned resize / performance impact

[Stefan Priebe - Profihost AG]

Hello list,

i'm planning to create a couple of VMs with just 30GB of space while 
using xfs as the main filesystem.

Now i alreay know that some of the VMs will grow up to 250GB while 
resizing the block device and using xfs_growfs.

Should i take care of that and format these disks with special parameters?

I've discovered that a 500GB volume has agcount=4 and 64000 blocks of 
internal log - while a 300GB volume resized to 500GB has agcount 7 ad 
only 40960 blocks of internal log.

Is it a problem if this grow will happen in small portions (30GB => 50GB 
=> 75GB => 100GB => ... 300GB)?

Thanks!

Greets,
Stefan