I've only got six sata ports on my motherboard. I'll use one for cache drive since it's my understanding that this will give faster transfer speeds. Will I lose any performance by connecting the parity drive to the controller? I'm thinking that parity checks are run so slowly that connection speed wouldn't really be a factor, but this is way outside my experience.

Not sure what you're asking here ... the motherboard ports are certainly fine for your parity drive.

 

Write speeds to the array will, of course, be notably slower with parity; but a cache drive offsets that slowdown by doing the actual array writes at off hours.

 

What I meant was if I connect the parity drive to the pci-e controller will this slow down parity checks?

As long as your PCIe controller has adequate bandwidth, the answer is no, it won't slow anything down.

 

If you're not connecting more than 2 drives per PCIe lane you should be fine.    Just for grins, however, I'd probably move one of your current connections to the PCIe controller and connect the parity drive to a motherboard port.    You can freely do this with UnRAID v5 (or v6), as the drives are tracked by serial number -- NOT by what port they're connected to.

 

Thanks. I'll go ahead and change the connection so parity and cache are both on the MoBo.

If you are using spin-up groups it is good to have the Parity and Cache in their own groups,  certainly in my two builds this means connecting them to motherboard ports as all of the ports on the SAS controllers are considered to be in the same spin-up group.

If you are using spin-up groups it is good to have the Parity and Cache in their own groups,  certainly in my two builds this means connecting them to motherboard ports as all of the ports on the SAS controllers are considered to be in the same spin-up group.

 

Thanks. Actually, if I understand my setup correctly (not guaranteed ) only the disk in use should be spinning up. I've basically got all disks assigned to a single share with spin ups and downs left as default settings.

Defaults should be fine.  Spin-up groups are designed to resolve the issue whereby spinning up a drive will cause a pause in access to another drive on the same controller.  For example, somebody is watching a movie, and somebody else does something that requires a different drive on the server to spin up -- and this action interferes with the movie ... "freezing" it until the other drive has spun up.    By having the involved drives in the same spinup group, then whenever one of them spins up, all of the drives in that spinup group will be spun up -- so you won't have this interaction issue.