Question Please explain this motherboard specification

[dstansberry]

Hi there. I've been looking at putting together a new i9-9900k PC, and have always had good luck with Gigabyte. I'm looking at the Z390 Auros Master, and I was curious about the product description of the M.2 ports.

Specifically, this:
1 x M.2 connector (Socket 3, M key, type 2242/2260/2280/22110 SATA and PCIe x4/x2 SSD support) (M2M)
1 x M.2 connector (Socket 3, M key, type 2242/2260/2280/22110 SATA and PCIe x4/x2 SSD support) (M2A)
1 x M.2 connector (Socket 3, M key, type 2242/2260/2280 PCIe x4/x2 SSD support) (M2P)

It's that "PCIe x4/x2 SSD support" part that bothers me. Is this telling me that I will not be getting full bandwidth if I plug an NVME Evo Plus into this slot? Is it telling me I can only use 2 SSD cards among the three M.2 slots? Is it some differentiation between SATA and PCIe drives placed there (M2P can only accept PCIe, but the other two go either way) Inquiring minds want to know!

I am aware that the ports share bandwidth with other devices, and think I have successfully figured out what I can and can't use simultaneously without compromise, but I'd appreciate some feedback from those wiser than myself (which would be a pretty broad group of folks!)

I think I can simultaneously use a single RTX2080ti in the top slot, two PCIe m.2 SSD's in RAID 1 in M2M and M2A, and two rotational platter drives in any ports other than 4 or 5.

 

[Rogue Leader]

All 3 slots support full PCIe x4 NVMe. There are older PCIe M.2 drives that are x2 that will work as well, that is all that spec is telling you. If you use the 3rd PCIe slot according to the board's specs, that M2P M.2 slot will run at PCIe x2. Also only the first 2 connectors support M.2 SATA drives, the 3rd does not. Not that that matter for your situation. M.2 SATA drives are a waste of money, they run at the exact same speed as cabled SATA drives, but just use the M.2 form factor for space purposes. Good for lower end laptops to save space.

And please for all that is holy do not RAID 2 M.2 drives, it is a waste of space, and time. You gain no performance benefit, you actually may lose performance, and if your array breaks your data is hosed and unrecoverable. Use them separately.

Read this for proof

https://www.tomshardware.com/reviews/ssd-raid-benchmark,3485.html

 

[dstansberry]

Thanks for your reply! I was baffled by the whole "x2 SSD Support" thing, and appreciate your making up for my lack of education!

I might have missed something, but that article appears to be in reference to striping (RAID 0). I'd be mirroring (RAID 1), for redundancy rather than speed. I agree with you completely in that I'd not want to risk the data loss associated with striping. (Although, technically, my data will be stored on the rotational platter drives, also RAID 1). And while I also agree with those detractors who say that a good backup is better than a RAID mirror, I love the convenience of being able to deal with a failed drive when it fits my schedule.

 

[Rogue Leader]

Thanks for your reply! I was baffled by the whole "x2 SSD Support" thing, and appreciate your making up for my lack of education!

I might have missed something, but that article appears to be in reference to striping (RAID 0). I'd be mirroring (RAID 1), for redundancy rather than speed. I agree with you completely in that I'd not want to risk the data loss associated with striping. (Although, technically, my data will be stored on the rotational platter drives, also RAID 1). And while I also agree with those detractors who say that a good backup is better than a RAID mirror, I love the convenience of being able to deal with a failed drive when it fits my schedule.

You're still wasting space and money. The failure rate on M.2 SSDs is like 0.02%, really you probably have a better chance of being struck by lightning. RAID mirror on hard drives makes more sense with their mechanical pieces, failure rates on spinning drives are anywhere from 2-10% depending on brand and model. The problem with a mirrored OS drive for you is that if something corrupts you now have mirrored copies of corrupted files. That includes if one drive fails or starts to fail. Most likely you will be re-imaging or reinstalling anyway. May as well just keep proper backups of your irreplaceable files with a network connected drive, and its just as seamless without wasting money on a second M.2 drive (or wasting space you could be using for .... games or whatever)

RAID really is for business applications whom need 0 down time, drives with data and software are in RAID so they can pop out a drive before it even fails once they know its on its way, or its aging out, or worst case if it fails. OS drives in such applications usually aren't in RAID but instead imaged daily so they can be reimaged and back up in an hour, since as I said the drive failure can corrupt the os on the good drive on the way out.