3 TB Compatibility Testing

At the time of writing, the current stable release of unRAID is unRAID 4.7. While 4.7 is a great product, one of its limitations is that it uses MBRs and not GPTs. In layman’s terms, that means that it is incompatible with any hard drive larger than 2.2 TB. As 2.5 TB and 3 TB drives are on the market today at attractive price points, many unRAID users have switched to using the latest unRAID beta (currently unRAID 5.0beta11), which has both MBR and GPT support. This means that any capacity drive can be used as a parity, data, or cache drive in the latest unRAID beta. I recently got my hands on 15 of the fabulous 3 TB Hitachi DeskStar 5K3000 CoolSpin hard drives. These are green drives that spin at 5400 RPM and use a SATA III (6.0 Gb/s) interface. I took the opportunity to test as much hardware as I had available to me for 3 TB hard drive compatibility. Here is the hardware I tested:

Supermicro X7SLA-H with a built-in Intel Atom CPU and 2 GB of DDR2 533 RAM (2 x 1GB)
ZOTAC GF6100-E-E with an AMD Sempron 140 CPU and 2 GB of DDR2 800 RAM (1 x 2GB)
Biostar A880G+ with an AMD Sempron 140 CPU and 2 GB of DDR3 1333 RAM (1 x 2GB)
Supermicro X8SIL-F-O with an Intel i3-540 CPU and 4 GB of DDR3 1333 RAM (2 x 2GB)
Asus M4A78LT-M with an AMD Sempron 140 CPU and 2 GB of DDR3 1333 RAM (1 x 2GB)

I also tested the 2 port PCIe x1 SIL3132 card that we use in certain GreenLeaf builds. I decided not to run any thorough tests on the Supermicro AOC-SASLP-MV8 controller as it has already been well established as being fully compatible with 3 TB drive through tests conducted by other members of the unRAID community.

All tests were performed using unRAID 5.0beta10 (which was the latest beta available at the time) and Joe L.’s preclear script 1.12beta (which is the only version of preclear currently available that supports 3 TB drives). A hardware component passed the test if it precleared successfully and was recognized by unRAID as an array drive. Here are the results:

Motherboard Backplane SATA Controller Result Duration (HH:MM:SS)
Supermicro X7SLA-H Norco SS-500 Onboard PASS 48:49:35
Supermicro X7SLA-H Norco SS-500 Onboard PASS 47:41:13
Supermicro X7SLA-H Norco SS-500 Onboard PASS 48:28:24
Supermicro X7SLA-H Norco SS-500 Onboard PASS 48:55:51
Supermicro X7SLA-H Norco SS-500 SIL3132 PASS 54:47:52
Supermicro X7SLA-H Norco SS-500 SIL3132 PASS 53:24:05
ZOTAC GF6100-E-E Kingwin 3-in-2 Onboard PASS 41:29:50
ZOTAC GF6100-E-E Kingwin 3-in-2 Onboard PASS 42:06:13
ZOTAC GF6100-E-E Kingwin 3-in-2 Onboard PASS 40:28:49
ZOTAC GF6100-E-E Kingwin 3-in-2 Onboard PASS 43:02:11
ZOTAC GF6100-E-E Kingwin 3-in-2 SIL3132 PASS 46:49:55
ZOTAC GF6100-E-E Kingwin 3-in-2 SIL3132 PASS 47:30:24
Biostar A880G+ Top Dock Onboard PASS 41:58:44
Biostar A880G+ None Onboard PASS 42:25:21
Biostar A880G+ None Onboard PASS 41:36:09
Biostar A880G+ None Onboard PASS 42:44:09
Supermicro X8SIL-F-O None Onboard PASS 42:12:56
Supermicro X8SIL-F-O None Onboard PASS 42:09:42
Supermicro X8SIL-F-O None Onboard PASS 41:22:09
Supermicro X8SIL-F-O None Onboard PASS 37:45:11
Supermicro X8SIL-F-O None Onboard PASS 38:29:49
Supermicro X8SIL-F-O None Onboard PASS 41:11:57
Asus M4A78LT-M None Onboard PASS 49:01:51
Asus M4A78LT-M None Onboard PASS 48:44:29
Asus M4A78LT-M None Onboard PASS 48:38:10
Asus M4A78LT-M None Onboard PASS 48:01:27
Asus M4A78LT-M None Onboard PASS 47:44:05
Asus M4A78LT-M None Onboard PASS 45:58:00

The good news is that every single piece of hardware I tested is fully compatible with the Hitachi 3 TB drives. However, as you can see from the duration results above, some of the preclear cycles were slower than others. At first I thought that certain SATA controllers were slower than others. Here’s a quick analysis of that hypothesis:

Motherboard SATA Controller Average Duration (hours)
Supermicro X7SLA-H Onboard 47.75
Supermicro X7SLA-H SIL3132 53.50
ZOTAC GF6100-E-E Onboard 41.50
ZOTAC GF6100-E-E SIL3132 46.50
Biostar A880G+ Onboard 41.50
Supermicro X8SIL-F-O Onboard 40.17
Asus M4A78LT-M Onboard 47.50

The slowest set of hardware was the Supermicro X7SLA-H and the SIL3132 controller with an average duration of 47.5 hours. This happens to the be motherboard with the slowest CPU and slowest RAM as well. The fastest set of hardware was the Supermicro X8SIL-F-O with an average duration of 40.17 hours. This also happened to be the motherboard with the fastest CPU and the most RAM. I believe these test results show that when preclearing 3 TB drives, the speed of the CPU and the RAM installed matters more than the SATA controller being used. Given this revised hypothesis, here’s the take-home analysis of this data:

CPU Amount of RAM RAM Speed Channels Average Duration (hours)
Atom 2GB DDR2 533 Dual 50.63
Sempron 140 2GB DDR2 800 Single 44
Sempron 140 2GB DDR3 1333 Single 44.5
i3-540 4GB DDR3 1333 Single 40.17

If you plan to preclear a lot of 3 TB drives, more RAM and a faster processor can help speed up the process by as much 10 hours.

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