OK, as a file server I use a Gigabit Ethernet PowerMac G4 with an upgraded 1.4GHz PPC7455 processor. Attached to it is a 4 drive 320GB RAID 0+1 attached to an Adaptec FireWire 800 PCI card. The RAID is two 2-drive (hardware striped) OWC FireWire 800 external drives (each contains 2x160GB drives), formatted together as a (software) mirrored RAID via OS X's Disk Utility (10.4.7).
So, just to sum up... two external 320GB FireWire 800 drives RAID'd as a software mirror (RAID 1) via OSX. Each of the external drives is a two-by-160GB hardware stripe RAID 0.
When the RAID set is attached to a single FireWire 800 PCI card, I get peaks of 85MB/sec according to Intech's QuickBench.
So I was at CompUSA and they had the same Adaptec FireWire 800 cards for $40, so I picked up another, so I could run each external drive off a separate FireWire channel. However, when each drive is connected its own FireWire card, my read speeds are cut almost in half.
This drop in speed is surprising to me, as I thought that two separate FW800 channels would be faster than sharing one.
Perhaps only software striped RAID sees a speed boost with two independent FW channels, whereas a software mirrored RAID (like mine) doesn't get a benefit?
Any thoughts?
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