4x12TB WD drives in P3 R4 for 36TB RAID5 - SOLVED

  • Last Post 19 March 2020
Jake Sargeant posted this 15 November 2017

Hi Promise, 

I posted a recent thread inquiring as to possibility of 4x12TB Western Digital Enterprise class drives working as a 36TB logical drive in RAID 5 on Pegasus3 R4. Link to forum thread here.

Unfortunately, you haven't yet posted these drives in your compatibility sheet. However, I would really like to get this working with these drives if it's possible and want to share how far I got and get some engineering/technical feedback. 

In short summary, the drives and capacities were recognized fine, disk array and logical drive were created successfully, synchronization process went through in full, but when that was over, I noticed no logical drive had mounted to my desktop nor was any logical drive showing up in Apple's Disk Utility. 

I could not find any reported errors either. 

I created an eventlog and saved out a subsysteminfo.html file as I've seen advised here on the forms and not sure how to attach here, but will be calling tech support to see what they can tell me by pointing them to this thread. In the meantime, any other tech support, thanks for looking over and helping me understand any thoughts as to why the logical drive didn't mount and what to try differently another time around as I think maybe I just missed a step or detail when I tried this the first time around per advice from a Promise tech support person by phone.





12TB drives recognized


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Jake Sargeant posted this 15 November 2017

Just got off the phone with Promise Tech Support (super helfpul by the way) and after a few attempts have the following good news to report. 

The attached image shows that I have a 36TB RAID5 logical drive that's currently synchronizing that shows up as expected in Disk Utility (at least I think so - correct me if you see anything wrong) and most importantly mounts on my desktop with 36TB available. 

Going to let synchronization run - takes almost two full days for a logical drive of this size - and then see how it handles test data situations before moving important data over to it. 

Things looking "Promise"-ing for now:).

Let me know if there's anything that doesn't look right here and any good ways to test that the RAID 5 system is stable and reliable before putting all my TBs and TBs of data on it. 


Jake Sargeant posted this 16 November 2017

Just wanted to share an update that I received some great tech support from Joe at Promise and my synchronization completed successfully earlier today. 

Now it's on to researching how to verify with proper software the transfer of a large amount of files and data via proper checksum'ing for porting over all my files on my P2 R4 over to this P3 R4

Also, if anyone is interested, I'm posting my read/write scores from Aja System Test Lite for the stock 4TB Toshibas that came included with the P3 and the read/write scores for the 12TB Western Digital Gold drives. Over 100MB/s gain in both read and write scores which I'll gladly take.


Cubic Ray posted this 19 March 2020

Hi Jake,

Do you think the 12TB drives will also work with the Pegasus2 R4?

I'm planning on buying four Ultrastar DC HC520 12TB drives to upgrade my Pegasus2 R4.