Implementing a write-through read cache by keeping a copy of hot data on a PCIe or direct-attached SSD, Proximal joins other cache software players EMC, FlashSoft (acquired by SanDisk), IOTurbine (acquired by Fusion-io), SanRad (acquired by OCZ), STEC, and independents Nevex (who partners with Texas Memory), and Velobit. While Proximal's initial release of AutoCache supports VMware ESXi 4.1 and 5.0 hypervisors, it integrates management functions through vSphere and vCenter. Proximal AutoCache is available immediately from its channel partners at a starting price of $999 for up to 500GB of cache capacity. [ VMware expands its role in data center virtualization by acquiring OpenFlow startup Nicira. Read about it at VMware Buys Nicira: Start Of Networking Wars?