Mixing drive speeds

[KMR]

I've read that it is not a good idea to mix drive speeds. My current pool is 6x3tb 7200RPM drives and I'm running out of space. I'm planning on buying 6 - 8 4TB drives that are 5900RPM. Will I have trouble adding another 6 - 8 drive vdev to this pool and striping it with my existing pool?

Thanks,

 

[Robert Smith]

If the top performance is needed then yes, mixing drives is not recommended. But it will not compromise safety. Some would even say that mixing different kinds of drives reduces the chances that the drives will fail at the same time.

On my live FreeNAS I am running four different hard drives in a RaidZ2 pool: two of which are 7200 RPM and two slower ones. I see nothing of concern due to that; my bottleneck is the network connection.

Adding a new empty pool to a pool that is almost full is another question entirely. There are some balancing issues to deal with.

 

[KMR]

Okay, network speed is my limiter as well. I was concerned about striping the pools together because it would simplify management of my files. I wouldn't need to mount other volumes or datasets and whatnot. What are the pros and cons here?