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Forcing a SATA drive into 3G Mode produces unexpected gains!

Posted July 14th, 2006, by rob-ART morgan, mad scientist
Updated July22nd with more drive examples

Back in August of 2005, Joel Vink of Sonnet Technology brought it to my attention that there were gains to be had with 3 gigabit per second (3Gb/s) SATA drives over those rated at 1.5Gb/s, assuming you had a 3G rated host adapter. I had argued that the drives were limited to 65MB/s so it shouldn't matter what kind of host adapter you use. My contention was true for large block transfers but I was able to confirm that small block writes -- smaller than the drive cache (or collective drive cache of a RAID set) -- would be faster on a 3G drive connected to a 3G host adapter.

When I heard from Seagate that removing the jumper from the new 7200.10 Barracuda forces 3G mode, I decided to see if there were gains to be had even on an individual drive.

We included results for the Hitachi 7K500 since part of our drives were set to 3G mode using a DOS utility. We also included results from a few other popluar drives.

Dual Raptors = Two Western Digital Raptor 10K 150GB SATA drives (WD1500AHFD) in a software striped pair (RAID 0)
Seagate 3Gb/s = Seagate Barracuda 7200.10 320GB SATA drive (jumper removed)
Seagate 1.5Gb/s = Seagate Barracuda 7200.10 320GB SATA drive (jumper installed)
Hitachi 3Gb/s = Hitachi Deskstar 7K500 500GB SATA drive set to 3G mode with DOS utility
Hitachi 1.5Gb/s = Hitachi Deskstar 7K500 500GB SATA drive still in factory default 1.5G mode
Raptor 1.5Gb/s = Western Digital Raptor 10K 150GB SATA drive (WD1500AHFD) -- does not support 3G mode
WD5000KS 1.5/3Gb/s = Western Digital WD Caviar SE16 (WD500KS) 500GB SATA drive (which is supposed to automatically adjust to 3G mode -- wink wink)
Maxtor 7V 1.5Gb/s = Maxtor MaXLine III (7V300F0) 300GB SATA drive

In all cases, the drive was connected to Sonnet Tempo E4P PCIe SATA 3G host adapter installed in the 4 lane PCI Express slot of our Quad-Core G5/2.5GHz Power Mac.

TEST ONE -- We averaged the 128K-512K random writes from five runs in QuickBench.

TEST TWO -- We averaged the number of 64K-256K completed write requests per second from 5 runs of 500 iterations each in DiskTester.

TEST THREE -- We averaged the 2MB - 10MB sustained writes from 5 iterations of the extended test in QuickBench.

TEST FOUR -- We averaged the 5 iterations of 4MB writes to the fastest portion of each volume using DiskTester.

Our goal was to simulate the typical types of disk activity carried on by OS X and various Mac applications. If our assumptions are correct, it means that when your SATA drive is in 3G mode and you are using a 3G rated host adapter, there are gains to be had even with a single drive. The gains are only in terms of write speeds in most cases and only in terms of transfer sizes smaller than the drive's built-in cache (16MB in this case).

We saw gains using other brands of 3G host adapters but they were not as dramatic is the Sonnet E4P. Then again, the Sonnet E4P does not support booting, currently.

If you can find a 3G SATA host adapter that will boot OS X and you have a true 3G rated boot drive, you should see a boost in speed over the factory SATA controller during typical operation of your Power Mac. Ideally, the 3G host adapter should have internal ports, allowing you to easily bypass the factory data cables.

Currently, the only 3G SATA adapter that can boot OS X is the PCIe card from FirmTek (SeriTek/2SE2-E). However, it features two external ports. I suppose you could boot from an external box or route the cables back inside your dual-core or quad-core Power Mac.

I'm encouraging Sonnet Technology (and other companies) to support booting on both their PCIe and PCI-X 3G SATA host adapters.

I encourage you to email me, , with your feedback on this issue. I'm curious if you want to be able to boot from a 3G SATA host adapter. I'm also curious if you plan to buy an Intel based Mac tower as soon as they are shipping or stick with your PPC based Power Mac. Carbon copy your email to Sonnet Technology if you want them to know what features you prize for SATA products.

The latest 3.AAE firmware in the Seagate 7200.10 fixes the slow sustained write speed we encountered when installed inside a Power Mac or Mac Pro. However, the random read speed is still very slow compared to other drives. So our recommendation of this drive is conditional.


Chris Karr of Intech Software had added some very useful new features to QuickBench including the abiity to average multiple iterations of the various small and large block random and sequential tests.

Lloyd Chambers has released version 2.0 of his useful DiskTester utility. Though it runs from within the Terminal app, we like the flexibility of defining the size of the test file, the size of the transfer or 'chunk,' and the area of the volume to be tested.

BARE FEATS reviews the Seagate Barracuda 7200.10 (large block transfers).

BARE FEATS reviewed the CalDigit 2 port PCIe SATA host adapter.

BARE FEATS reports on the Sonnet Tempo SATA E4P host adapter which supports up to 20 drives via Port Multiplication.

BARE FEATS reports on the HighPoint RocketRAID 2322 with two mini-SAS external ports that support up to 8 drives in special 4 drive enclosures with Infiniband connectors.

BARE FEATS reports on the FirmTek SeriTek/2SM2E ExpressCard/34 SATA host adapter for the 15" and 17" MacBook Pro.

Visit AMUG's review index for some additional tests of SATA host adapters and SATA enclosures.


FirmTek (host adapters, enclosures)

Granite Digital (drives, host adapters, enclosures, internal kits, cables)

MacGurus (drives, host adapters, enclosures, cables)

MaxUpgrades (host adapters, enclosures, internal kits)

Other World Computing (drives, host adapters, enclosures)

ProMax (host adapters, enclosures, complete storage solutions)

Small Dog Electronics (drives, host adapters, enclosures)

Sonnet Technology (PM SATA host adapters, enclosures) (drives, host adapters, enclosures, internal kits) (drives -- only with enclosures, host adapters, enclosures, internal kits)

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2006 Rob Art Morgan
"BARE facts on Macintosh speed FEATS"
Email , the webmaster and mad scientist