Hi - I added 3 new 20TB Western Digital SAS drives (Western Digital Ultrastar DC HC650 WSH722020AL4204 20TB 7.2K RPM SAS 12Gb/s 4Kn) to my HP Z840 workstation, but they don't show in Unassigned Devices or Preclear Disks. The original 1TB SAS drive shows OK. The onboard Serial Attached SCSI controller is a Broadcom / LSI SAS2308 PCI-Express Fusion-MPT SAS-2 (rev 05). I have also tried attaching the drives to a HBA-enabled HP H240 SAS controller card with the same results. The log file shows that Unraid sees the drives, but the 20TB WD drives are all listed as "Unsupported ZBC host-managed device". Diagnostics attached.  Any advice gratefully received

Cheers,

Steve

tower2-diagnostics-20230104-1736.zip

Edited January 7, 20233 yr by Steviewunda
Solved

Reads like its host managed SMR, which has some support in recent Linux kernels.

@JorgeB would likely know if its possible on Unraid.

Yep, that's a host managed SMR drive, while there's some kernel and fs support (at least from btrfs) for those in recent kernels not sure that Unraid supports them, also those drives should only be used with an OS that is aware of them, or performance will be terrible, IMHO you should return it if possible and get a CMR drive, or at least a device managed SMR drive.

Thanks Jorge

I have since updated the firmware on the H240 controller and tried a Windows 10 install (same as Unraid - drives not detected) and an Ubuntu 22.10 install - which DID detect controller and drives, and I was able to format and use the drives in Ubuntu.
But I want to use Unraid, so I will sell the SAS drives and replace them with SATA drives - do you know if 20 TB SATA drives would be compatible with the onboard controller in my HP z840? Or the HP H240 controller?

Should be.

Looking at some less expensive 4kN hdds myself and came across this: https://techmikeny.com/blogs/techtalk/compatibility-pain-points-4kn-hard-drives-and-backwards-compatibility-with-raid-controllers#:~:text=4Kn hard drives (4K %3D 4096,be used for your data.  Of particular note is this statement: "This post will give some background on 4Kn sectored drives and some compatibility issues with Dell and HP RAID controllers that are not compatible with 4Kn hard drives." Given your Broadcom/LSI is likely considered a RAID controller, (my experience with this brand), is possibly your incompatibility with the 4KN hdds. My research and your experience are good reason I will not be purchasing these hdds.

Any news about the current kernel support host managed SMR or not? HDD prices are crazy this time, the price of those 4kN host managed SMR are pretty attractive. @JorgeB

AFAIK while it should be supported by the current kernel, it's not supported by Unraid, so possibly would only work for manually formatted unassigned devices.

I was looking into this, hm-smr drives don't support using a normal partition; you must create the filesystem using the whole disk (/dev/sdX), Unraid currently requires a partition to work, so while this may be supported in the future, I would not expect it in the near future; it would require big code changes by LT.