Microchip recently showed off its newest generation of SAS and NVMe expanders and adapters. The new Microchip 24G SAS solutions are designed for the emerging PCIe Gen4 slots we will start to see in mainstream x86 servers with the AMD EPYC Rome launch next quarter. Recently, Microchip showed off its new adapters and expanders that are set to double SAS bandwidth along with a doubling of PCIe bandwidth.
Microchip 24G SAS for PCIe Gen4 Servers
Microchip 24G SAS products are coming. The company after the Microsemi acquisition has a portfolio of SAS adapters and SAS expanders that it is readying for the 24G SAS generation. This includes its new Microchip SmartROC 3200 series of tri-mode adapters designed to work with SAS4, SATA, and NVMe. While SATA is stuck at 6Gbps speeds, 24G SAS4 and NVMe storage will consume more bandwidth. As a result, the company has tri-mode adapters as well as the ability to use Dynamic Channel Multiplexing to get more bandwidth to SAS4 expander enclosures.
To show what will happen with the SAS3 generation, here is a diagram from the company. As you can see, the SAS3 controllers on a PCIe Gen4 interface have more bandwidth than eight lanes of SAS3 to an expander can provide. This is so even if the storage on that SAS3 expander can provide more than twice the bandwidth of 8x SAS3 lanes.
Using 24G SAS and Dynamic Channel Multiplexing, SAS expanders can uplink more bandwidth to the RAID controller or HBA, thereby more effectively using the PCIe Gen4 x8 link back to the server.
Over time, SAS4 SSDs will come out to saturate the uplink with only eight drives. At the same time, using today’s SAS3 SSDs, and large hard drive arrays, one has the ability to alleviate a SAS bottleneck with the new SAS4 solutions such as Microchip 24G SAS RAID controllers and SAS expanders.
24G SAS is still not here yet. The initial plugfests are just kicking off this year. Still, we expect that as the PCIe Gen4 server ecosystem becomes more robust, we will see 24G SAS products come to market.