The DDRdrive is a product rather difficult to place in a defined category.
Based on a PCI Express 1x card, it features 4x 1GB DDR modules associated to a SSD of the same capacity. If its writing and reading performance might now look standard to other SSD with respectively 250 MBs and 150 MB/s, it nevertheless offer up to 300,000 input/output per second, in other words 10 fold than the Intel SSD so far considered as the reference.If the storage capacity is low, you can add several unit of DDRdrive to pool them. Such solution might be interesting for some data servers manipulating thousands of files of small sizes. As you already understood it, the associated SSD is only used to backup the data priori switching off the computer. According to the manufacturer it only takes one minute to complete this operation.