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When it comes to 1, 2 and 4 drive sets,
which is faster, FireWire 800
or Serial ATA?

Posted September 1st, 2005, by rob-ART morgan, mad scientist

I thought this question had been answered in previous articles but it keeps coming up again and again -- especially in relation to one, two and four drive configurations. So we gathered up a bunch of Hitachi 7K500 drives and performed a new round of testing to clarify the issue.

SATA = Serial ATA I; FW800 = FireWire 800
1x1 = one drive on one data channel; 2x1 = two drives on one data channel;
2x2 = two drives on two data channels; 4x1 = four drives on one data channel;
4x2 = four drives on two data channels; 4x4 = four drives on four data channels


1. Blame it on Data Channels
The main key to the speed advantage of Serial ATA is that each drive not only has a dedicated port but each port represents a dedicated data channel capable of 150 to 300MB/s, depending on the host adapter used.

With FireWire 800, the drives are typically daisy changed on the same 100MB/s data channel. Even if you install a FireWire 800 PCI card with 4 ports, those four ports share the same 100MB/s data channel -- as if they were daisy chained. It would take three PCI cards plus built-in FireWire 800 to equal four data channels.

Even if you have spare slots for that many PCI cards, the popular two and four drive FireWire 800 hardware RAID boxes only have ONE FireWire 800 input port. If you want a FireWire 800 RAID set with one data channel per drive, you'll have to buy individual FireWire 800 enclosures for each drive and connect each enclosure to its own PCI card (though one drive could use the factory built-in FireWire 800 port). That scenario can be unwieldy and impractical since I doubt you have three spare PCI slots in your Power Mac to dedicate to FireWire 800 cards.

2. Blame it on the G5 Power Mac, which is FireWire 800 "Challenged"
We discovered something back in 2003 when the first G5 Power Mac was introduced. When running FireWire 800 RAID sets, the sustained write speed of the G5 Power Mac was much slower than the G4 Power Mac (and PowerBook). In one dramatic test, we had installed three FireWire 800 PCI cards in both the G5 Power Mac and G4 Power Mac. That, along with the built-in FireWire 800 port, gave us four data channels -- one for each of the four drives. We striped the four drives (RAID 0) on each machine. When we ran the large sustained write test, the G4 Power Mac recorded TWICE the speed of the G5 Power Mac (180MB/s versus 90MB/s).

Let me say that again. The G4 Power Mac was doing sustained WRITES at TWICE the speed of the G5 Power Mac.

In the graph below, we used our more recent hardware to show the advantage of the G4 Power Mac over the G5 Power Mac when running FireWire 800 storage units. Notice we include results showing how adding a second data channel boosts the speed of the FireWire 800 storage unit.

In the graph above, "G5" = G5/2.5GHz Power Mac and "G4" = G4/1.42GHz Power Mac

After two years, the G5's FireWire 800 write speed deficiency is still there. That, along with seeming ambivalence by Apple to fully promoting the advance of FireWire technology, has had the effect of elevating Serial ATA over FireWire as the external storage technology of choice -- especially since hot-swap and bootability has been added to SATA host adapters.

The speed of a single FireWire 800 drive isn't that different from a single SATA drive unit, but once you start striping two or more drives to form a RAID 0 set, the Serial ATA drives begin to pull away. Whether you choose a dual or quad drive RAID 0 enclosure, you'll get more speed if you go with Serial ATA instead of FireWire 800.

If you choose to go with FireWire 800 RAID, you can squeeze out more speed by adding additional data channels (not to be confused with extra ports -- see discussion above).

FireWire 800 and SATA RAID enclosures differ in look, features, serviceability, and price, but the performance is governed by drives used, host adapter, and number of data channels.

The consumer has much to choose from when it comes to FireWire 800 and Serial ATA enclosures. Here's links to some of great examples of RAID enclosures for two or more drives, most of which we have tested:

Other World Computing Mercury Elite-AL RAID two drive enclosure
TransIntl miniG FW800 two drive and four drive enclosures
Wiebetech TrayDock Extreme FW800 two drive and four drive enclosures
FWDepot PDS2-Go two drive enclosure
G-Tech's G-RAID two drive enclosure (and upcoming G-RAID Q)
LaCie's BigDisk Extreme and Bigger Disk Extreme enclosures

FirmTek SeriTek/1EN2 two drive enclosure (the only one where drive plugs directly into backplane)
Kano Tech X-Spand two and four drive enclosures
TransIntl miniG SATA two drive and four drive enclosures
Wiebetech TrayDock eSATA two drive and four drive enclosures
G-Tech G-SATA two drive enclosure
Sonnet Technology Fusion four drive enclosure

LaCie S2S SATA II 5 drive RAID system

If security and reliability is more important that speed, then you could consider the RAID boxes with box level RAID 5 including:
Wiebetech RT5
FWDepot eRAID 5 system with clustering


BareFeat's Review of the Wiebetech G5Jam internal drive kit for G5

BareFeat's Review of the TransIntl SwiftData 200 internal drive kit for G5

AMUG's Review of the Drive Bracket internal drive kit for G5

BareFeats' Review of SeriTek/1V4 SATA PCI-X host adapter (4 internal ports)

BareFeats' review of the Sonnet Tempo-X PCI-X SATA 4+4 PCI-X host adapter

BareFeats' Reveals the "Fastest 7200RPM Drive for the G5 Power Mac"

Seagate Explains Native Command Queing (NCQ)

WHERE TO BUY FIREWIRE 800 and SERIAL ATA ENCLOSURES (with or without drives installed)

FirmTek (host adapters, enclosures, and cables)

Granite Digital (enclosures, host adapters, brackets, and cables)

Kano Technologies (enclosures and host adapters)
Use "BAREFEATS" coupon code to get 10% off the X-SPAND or 5% off everything else

MacGurus (host adapters, enclosures, bare drives, coolers, hot-swap trays, cables, converters)

MaxUpgrades (internal drive kits for G5)

Other World Computing (enclosures, bare drives, and host adapters)

Small Dog Electronics (enclosures and host adapters) (enclosures, bare drives, and host adapters) (enclosures and host adapters)

FWDepot (enclosures, host adapters, cables)

Sonnet Technology online store (host adapters, enclosures, and cables)

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2005 Rob Art Morgan
"BARE facts on Macintosh speed FEATS"
Email , the webmaster and mad scientist