Architecture

OCZ revodrive x2

Built on a compact 125 x 181 x 22mm PCB, the OCZ RevoDrive X2 has the same footprint as the original RevoDrive, with the daughter card sitting on very small risers above the memory chips on the base card.

In total, the X2 240GB uses 64 4GB 34mm Intel/Micron MLC (Multi-Level Cell) modules to achieve its capacity, with them being split 16 per side of the base card and 16 per side of the daughter card.

The four 64GB memory partitions are each controlled by an eight-channel SandForce SF-1222TA3 SBH controller and the data flow is controlled by an on-board SATA 3Gbps RAID controller (SiS 3124) which uses a pre-built RAID 0 (Stripe) array.

OCZ's close relationship with SandForce has enabled them to pair the controllers with the latest SF-1500 firmware, which gives better random write speeds.

While the card has an x4 PCIe 2.0 interface, with a potential 2GB/s of bandwidth (500MB/s per lane), it works only at PCIe 1.1 electronically, which gives it half the bandwith at 1GB/s.

Even this is far in excess of the 550MB/s of bandwidth that is supported by a pair of SATA cables.

This is good news, because OCZ claims maximum read/write speeds for the RevoDrive X2 of 740MB/s and 720MB/s respectively.

The one note of caution is that unfortunately the SIS RAID controller doesn't support the Windows 7 TRIM command.

The SandForce controllers do support it, but the RAID controller overrides them and blocks the command. So instead of using TRIM, the SandForce controllers have algorithms programmed into them to sort all of the rubbish data.

The worrying thing about this situation is that the OCZ RevoDrive X2 has the potential to really suffer from a downward spiral of performance coinciding with its long-term use.