# Improving ZFS on 4k block WD disks



## Pushrod (Feb 29, 2012)

I have a 4x2TB RAID-z array using WD Green 4k block disks. I didn't know anything about the performance issues when I set it up, and by the time I transferred files, it was too late to really do anything about it.

Since then, I have filled the array, so I bought one more 2TB Green drive, which I will use as a normal disk with no redundancy (not needed). Having this disk has given me the idea that I may be able to use it to fix the performance issues with the array, one disk at a time. What I am thinking is this:


Install new disk into machine
"Bless" it with the proper config for good ZFS performance.
Take out one of the existing disks, and then rebuild the array with the new, blessed disk.
Repeat the last two steps, one by one, until all four disks are upgraded, making the array fast.

My two questions are:
Is this possible?
What do I need to do to each disk (something about GEOM NOP right)?


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## phoenix (Mar 1, 2012)

Sorry, it doesn't work that way.  The ashift property of of a vdev is set at the time the vdev is created and cannot be changed afterward.


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