VDIMM

VDIMM, short for volatile DIMM, is a memory module that uses DRAM to store data as long as power is supplied. It provides high-speed, low-latency memory for processors and is commonly used in servers and data centers to deliver fast access to data and high memory bandwidth.

Unlike non-volatile DIMMs (NVDIMM variants), VDIMMs do not retain data after power is removed. Some VDIMMs may include power-loss protection (PLP) circuits, such as capacitors, to sustain operation during brief power glitches and to complete in-flight writes, but this does not make the memory non-volatile. Data stored on a VDIMM remains volatile and relies on power being supplied to preserve it.

VDIMMs use standard DDR memory interfaces and form factors, including UDIMM, RDIMM, or LRDIMM, and they conform to JEDEC specifications for DDR3/4/5 architectures. They are installed in server motherboards with memory controllers that typically support error detection and correction (ECC) in many enterprise configurations.

Use cases for VDIMMs include as the main memory for latency-sensitive workloads, in-memory databases, caching layers, virtualization, and other high-performance computing scenarios where rapid access to large datasets is essential. They are often evaluated alongside NVDIMMs in storage and data protection plans, depending on whether persistence across power losses is required.

In summary, VDIMMs provide fast volatile memory suitable for servers and performance-critical applications, with data retention limited to powered operation. For persistence across power outages, non-volatile memory options like NVDIMMs are used.