Comment by ricktdotorg
3 years ago
in 1999 i was working for an NYC fintech startup (first after-hours ECN to publish quotes on SuperSOES) and around then we paid an absolute fortune for a battery-backed-up giant RAM disk. i don't remember how much RAM it had, but it was a ruddy big rackmounted box with 2x car batteries and a lot of soldered RAM in it, and it allowed us to trade-match much faster than our competitors at the time. the RAM was presented as regular block devices to Linux, so we could do what we wanted with it. that RAM disk was our main competitive advantage, right until the CEO decided to do crimes and the whole thing was bought up by E*Trade, staff got screwed over, and it all died a big messy death after 9/11. loved that RAM disk tho.
In 2013 I was working for a mobile game company that dropped a metric shitload of cash in Big Blue's lap for an enormous "RAM SAN".
IIRC it was a 1 or 2U unit with a few small lithium ion batteries inside. Phenomenal unit. It could have been configured as a block device but we used it for hot data in an auto-tiering setup with SSDs and rust in the other tiers.
Loved it to bits. No matter what we threw at it, the network was always our bottleneck.
The Solace appliances use a card called the Assured Delivery Blade that basically consists of 4GB of DRAM attached to an FPGA on a PCIe card with a pair of 10Gbps SFP+ interfaces and a bunch of super capacitors to keep things running when the power fails. On power failure, the FPGA dumps the DRAM into flash to ensure persistence. The whole thing enables the persistent messaging feature to acknowledge reliable delivery of persistent messages in a few microseconds. The first version was developed back in 2008, well ahead of NVMe and other low latency storage mediums.