Rambus' technology to make Direct DRAM chips sufficiently fault tolerant for use in mission-critical servers, due to be unveiled this week, may not be as new as UK paper Electronics Weekly, which broke the story, claimed. It now appears that Rambus' 'Chipkill' technology could well be licensed from IBM, according to many Register readers. "It sounds very similar to IBM's Chipkill-ECC initiative, which is one the streets now (in Netfinity 7000M10, etc.)," writes Margus Rohtoja from Estonia. "The guys at Microelectronics even named it RAID-M, making [your] comparison with RAID-5 very appropriate. It gives same level of protection as RAID-5, and has similar drawbacks: reduced capacity due to extra space needed for checksums, and slightly reduced performance. Also, the memory subsystem takes an additional performance hit when one of chips is dead -- its contents will be deduced from healthy chips and checksums. Just like RAID-5... "Ordinary ECC doesn't fix multi-bit failures, but when memory capacities are reaching gigabytes, probability for multi-bit errors increases ominously." It has to be said, Margus is an IBM tech support guy, so he's clearly keen to point out Big Blue's success here. However, we received many similar comments from other readers who don't appear to be IBMers. Our thanks to everyone who emailed us with details of the technology. The interesting thing about Chipkill is that it was apparently designed for NASA to be used in its Mars Pathfinder probe. Presumably, this will ensure all Netfinity servers are suitable Heat Ray-resistant when the Martians finally show up on Earth... ®