Emerging storage technology: port-multiplier external SATA II
I’ve followed Norwegian photographer Bjorn Rorslett’s very useful web site for years, and his outstanding review of the Nikon D200 is now online. Bjorn’s vast experience lends a particularly useful and interesting viewpoint to anything he reviews. The D200 review is his best review ever—don’t miss it if you have an interest in the D200!
Work continues on the diglloyd Nikon D200 review, presented as a comparative review with the Nikon D2X, and possibly with some Canon EOS 5D comparisons. It will likely take several more weeks to complete.
I’ve never much liked noise reduction, but the results obtainable in Nikon Capture show that it is a welcome feature for some images. Read the article, and see for yourself.
Some new products have already been announced and I’ve learned through other means that more will follow from other vendors. For external high-speed storage, Firewire 800 never delivered (especially with the write-performance bug on G5 PowerMacs), and eSATA (external SATA) is now emerging as the de-facto performance standard.
SATA first emerged as an internal storage technology supporting 2 drives via the motherboard. Now what we see emerging is external SATA II, capable of 3 GB/sec (twice the original SATA 1.5 GB/sec). Only a 8 drive striped RAID array can saturate that kind of bandwidth, so there’s room to grow.
But more importantly, we see port multiplication emerging, which allows up to 5 drives per physical cable (at least in the Sonnet E4P implementation). The Sonnet Technologies card has 4 ports, supporting 5 drives per port, or 20 drives with a single card. The claim is 300MB/sec per port. In theory, this would allow 1200MB/sec with 20 drives, though other factors are likely to limit that theoretical speed. Of course this is “bleeding edge” stuff, with Sonnet the first Mac vendor to announce a product—I advise waiting 2-3 months before spending money on this technology. As usual, barefeats.com is a great place to keep abreast of this sort of thing.
Why is port multiplication good? I currently use the FirmTek SeriTek/2eEN4, a very reasonably priced and very high quality external SATA I/II 4-drive storage unit. The downside is that it does not support port multiplication and thus 4 cables and 4 ports are needed—one for each drive in the unit. This not only leads to a tangle of cables, but it means that the PCI card supplying those 4 ports uses one of two slots in the PowerMac G5 (the GeForce 6800 Ultra DDL video card occupying two slots). Addition of another external unit means the last slot would be scarfed up by another card. With port multiplication, four (4) external units could be supported with 4 cables and one card, a much more flexible solution, especially if you want a master unit, and an online backup unit.
