AMCC, formerly 3Ware, has the longest history in the ATA RAID arena. As a matter of fact, its Escalade 7000 series was one of the very first products to introduce enterprise features into the ATA RAID market. 3Ware is also one of very few companies that actually develops the complete architecture in-house, rather than resorting to third party components.
We had some difficulties keeping track on all of their models, but according to the AMCC website, the 9550SX is the 7th generation product by 3Ware. Its PCI-X interface was bumped to 64 bits and 133 MHz, and a PowerPC processor was added to do the XOR parity calculations. All 9500 series cards support staggered drive spin-up, which is required when large numbers of drives are being used to ensure there is no spike in power demand that might overload the power supply. Also, the 9550SX is the only product besides the Broadcom/Raidcore BC4000 family to support multiple RAID cards in order to boost up arrays considerably.
What is particularly impressive is the 9550SX's ability to migrate one RAID level to another. All you have to do is make sure that the target RAID capacity is large enough to store what you already have in use. In addition to that, 3Ware clearly worked on improving the feature set in order to at least match Broadcom/Raidcore's BC4000 series. Due to its software RAID design, the BC4000 used to be more flexible from a software point of view, but with the introduction of several new features (see feature table) AMCC/3Ware can now go head-to-head with Broadcom/Raidcore.
Unfortunately, the 9550SX does not have an acoustic alarm, which can be useful in environments where an administrator is close to the host system and the number of systems is limited. Also, we believe it would have been a nice upgrade for 9000 series users to be able to keep using the battery backup unit - this is not possible.
We found it odd to see the 8-port version 9550SX-8LP, come equipped with a total of 10 ports. As you can see on the image below, the design does not physically allow using more than eight ports. It doesn't really make a difference, but it's noteworthy.
From a performance point of view, the 9550SX series also seems to be one of the best choices today. In most of our I/O benchmarks, it runs neck and neck with Areca's 1220 model. When it comes to coping with a degraded RAID 5 array, the competitor delivers better performance. However, AMCC/3Ware still has the advantage of being much better equipped with features - which in everyday life is sometimes more important.