USSD Series

The USSD Series (Universal Solid State Disk) products are billed by the vendor as I/O acceleration appliances, and are, in fact, rack-mountable devices that can be accessed and operate in the same manner as external Fibre Channel or SCSI disk drives; i.e., the devices can be accessed and used by host computers just as they would a standard external FC/SCSI drive. The difference is that the USSD drives are not platter-based hard drives, but instead leverage DRAM for their memory storage. As such their key feature is the speed with which data can be accessed: Access times are listed as low as 10 microseconds (not milliseconds), with total random access bandwidth listed at up to 4.8 GB/sec (depending on the interface).

The drives are served in capacities of 16, 32, 64, 128, and 256 GB; and capacity can be scaled upwards by daisy-chaining the drives together.

Three interface possibilities are offered with the drives: 4 Gb/sec FC (up to 8 ports possible; two provided in the standard configuration); 320 MB/sec SCSI (4 maximum, 2 standard), or 3 Gb/sec SAS (4 max, 2 standard). A single USSD drive can support multiple types of interfaces, all with access to the drive's memory. FC performance is listed at 100,000 IOPS per port; SCSI performance is 25,000 IOPS per port; and SAS is 72,000 IOPS per port. The vendor targets the drive to top-tier storage requirements where the most often utilized "hot" files can be offloaded to the device, while traditional disks continue to service "cold" files.

Features of the drive include 64 dedicated error correction/detection bytes per 512 byte sector; an Ethernet port for remote management (Telnet-based); dual hot-swappable power supplies; support for Chipkill (provides the ability to auto correct multi-bit memory errors, or if the error cannot be corrected to shut down the effected DIMM without shutting down the entire device); and support for up to 4 (2 standard) hot-swappable data retention disks--disks which are automatically written to / restored from when the unit is powered down or up (with save/restore performance listed at 3.5 GB/min). A separate and optional 1U UPS unit is also offered by the vendor for use with the drives.

The retention drives/UPS features of the drives deserve special attention; as power is required to the device in order to retain the data stored in the DRAM memory. The vendor notes that with a sudden loss of power, the unit will continue to function normally for one minute; after which it relies on an external UPS (provided by the customer or the vendor's own separate UPS unit) to provide enough time to ensure current data is backed up to the retention drives. The vendor notes the ability to provide CDP protection to the retention drives, as well.

The USSD drives are now available in two models: The original USSD 200 series described above, and the new USSD 300 series, which are offered both in 1U and 2U form factors (both up to 256 GB) boasting 100,000 IOPS per FC port and aggregated FC bandwidth of up to 4 GB/sec. A 4U "Tower" model is also offered; as is a 1U 128 GB model that couples the memory with a server for customized deployments.

The drives ship with a 3-year warranty and are made to order; the vendor notes an expected delivery time of 4 to 6 weeks. Custom versions and form factors of the drive are also offered by the vendor. Pricing as of this date starts at $18,000.

Visit the Solid Access Technologies Web site for further information.