adding drives to existing RAID array

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Dec 28, 2017
Hi all

So I have finally been delivered the hardware that I wish to set up my FreeNAS on.

I have an oldish radon 16 bay server with dual xeon 74 gig of ram.

First question

I intend to put WD red NAS 6TB drives in to populate, they come in standard 5400 rpm 64meg cache and pro 7200rpm 128meg cache.

I intent to use the raid to serve compositing work stations, what are the pros and cons of going with either the pro or standard WD 6TB drives

Second question

I cant afford to outlay 5 - 6 thousand $$ for 16 drives right away

So if I wish to strip these drives with dual disk parity can I start out with say 6 drives and progressively add drives as I can afford them to the array with out starting from scratch and data lose?

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Aug 19, 2017
ZFS pools consist of vdevs. A vdev can have several layouts. Generally a vdev cannot be changed once it’s been created (there are some exceptions). So, you can add drives to an existing pool as new vdevs (you cannot remove vdevs though). If you build a RAIDZ2 vdev of your 6 drives then you need to buy enough drives to build another vdev. I wouldn’t mix vdev layouts in the same pool so that would mean you need to buy another 6 drives for another RAIDZ2 vdev. I believe the sweet spot for performance is 8 drives for RAIDZ2 however. Also, I wouldn’t mix drive performance in the same vdev and or pool.

All this is explained in the documentation though. I would recommend you read the FreeNAS manual cover to cover and the FreeBSD handbook on ZFS before you start.
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