I've worked in IT for years and have built my own Windows based gaming PC's from at least the last 20 years but also I'm fairly new UnRaid and Linux altogether. I was wondering if anyone here can help with a strange issue. I had my ZFS pool drives connected directly to my motherboard's (ASUS P8Z77-V Deluxe) SATA controller and they were visible and working fine in my UnRaid server (Version: 6.12.4) running in an old Corsair 750D case, then I stopped the array, shut down the server and moved all my hardware in to a Norco 4224 / Logic Case 4324 clone server case (https://www.amazon.com/RROYJJ-Rackmount-Server-Chassis-Hot-Swappable/dp/B095YMXW1K) that has 24 hot swap bays and I added an Avago / LSI 9305-24i HBA card just like this one: (https://www.amazon.com/LSI-Controller-05-25699-00-9305-24i-PCI-Express/dp/B01BDZWLV6) with these cables for the SAS / SATA backplane in the case: (https://www.amazon.com/Internal-SFF-8643-SFF-8087-0-8-Meter-Flexible/dp/B086V2TTBD). When I powered the system on and after UnRaid OS loaded, Cache / Parity / Array drives showed up and were ready to go. Two new HDDs also showed up and were ready to be pre-cleared (2 new WD Red Pro 4 TB drives) and 2 new Sam 850 Pro 1TB SSDs that I added to the Array cache. The only drives that did not show up and remain missing, were 4 old laptop 320 GB HDDs in a ZFS pool: 

 

To try to figure out why the ZFS pool drives aren't populating, I've 1. Moved and swapped working drives with non-working drives to rule out the case's backplane and the cables from the HBA as the backplane on this case is composed of 6 individual mini backplanes of 4 drives each  ordered in 6 "rows" and 4 "columns". 

 

So each of the 6 mini backplanes makes a "row". 2. The HBA displays detected drives before the OS boots up and I couldn't see the missing ZFS pool drives there either: 

 

In it's configuration utility that I can also access before the OS loads, I can see the detected drives as well, the list refreshes about once every 5 seconds, so I can disconnect drives an reconnect drives an see them leave and enter the list: 

 

While in this view, I also swapped working with non-working drives, but there was no change. 3. Lastly, I flashed the HBA with what I believe to be the latest BIOS and IT-mode firmware from Broadcom's website "9305_24i_Pkg_P16.12_IT_FW_BIOS_for_MSDOS_Windows.zip". The following screen in the HBA's configuration screen shows the version numbers: 

 

I'm hoping some of the great minds here can help me figure this out.

UPDATE: I tried connecting each of the missing drives to the server via a USB to SATA adapter to bypass the HBA and case backplane and the drives appear in UnRaid but I noticed that the serial numbers on each drive look different. I have the Unassigned drives plugin in UnRaid, it makes a Historical drives section below the Unassigned drives section, there I can compare the serial numbers with the missing drive serial numbers in the ZFS pool section 

 

I'm wondering if the HBA changed the serial numbers and if this is even related to the drives being in a missing state.

33 minutes ago, Mephisto76 said:

I'm wondering if the HBA changed the serial numbers and if this is even related to the drives being in a missing state.

What changes the serial is the USB adapter, looks like the LSI is just not detecting the drives, since they are OK and cables/backplanes were ruled out it could be just a compatibility issue with those old drives.

I was starting to come to that conclusion myself, but hopefully someone else can chime-in as well.

1 hour ago, Mephisto76 said:

I was starting to come to that conclusion myself, but hopefully someone else can chime-in as well.

Not sure you can have a better opinion than JorgeB on disk controllers in those forums.