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Originally published at Internet.comThe RamSan product line from Texas Memory Systems are Solid State Drives (SSDs) that leverage DDR and/or Flash memory (depending on the model) for data storage.
In the case of DDR-based SSD systems, the primary memory is volatile in that it requires power to hold the data and will forget that data whenever power is lost. For this reason, each of the RamSan products are protected with both battery backups, enabling the drive to survive a power outage long enough to perform a graceful shutdown; and some form of non-volatile backup storage, to which the live data can be written before the drive is actually powered off (this data is then read back into the DDR memory for access when the drive is powered back up).
The drives are accessed via 4 Gb/sec FC or 4x InfiniBand (10 Gb) ports (InfiniBand not available on the 440 model); with the vendor listing compatibility with "most" open systems, HBAs, and switches, including Windows, Linux, Solaris, HP-UX, AIX, Mac OS, Emulex, LSI Logic, QLogic, Brocade, Cisco, and more. To the operating systems, the drives appear as "just another disk drive," and have the ability to provide up to 1,024 LUNs to host operating systems, each of which can be formatted with its own file system.
Other features common to the drives include ChipKill, for the correction of multi-bit failures up to and including an entire chip; wear-leveling for Flash-based systems (spreading writes evenly across the Flash memory to extend its overall life); and soft-error scrubbing, which works in tandem with ECC-based protection in that ECC-corrections are re-written to memory and re-read for verification to ensure the error was (or was not) the result of a hardware failure. The result, according to the vendor, is a more accurate report of memory errors to the system log and thus an eventual reduction of unnecessary memory board replacements.
As alluded to above, four different RamSan models are offered by the vendor.
The RamSan 300 is the entry level offering of the group, providing from 16 to 32 GB of capacity and accessed via up to four (two standard) 4 Gb/sec FC ports or two (one standard) 4x InfiniBand port. The RamSan 300 is a 3U box that is based on DDR memory and includes hard drives for the non-volatile data backup. Performance is listed at 200,000 IOPS, 1,500 MB/sec throughput, and latency of less than 15 microseconds.
The RamSan 400 is similar to the 300, but increases capacity to from 32 to 128 GB and performance to 400,000 IOPS and 3,000 MB/sec throughput. Two FC ports are standard, with up to eight possible (or one InfiniBand with up to four possible).
The RamSan 500 model is actually somewhat of a hybrid model, in that the primary memory storage is not volatile DDR but instead is non-volatile Flash memory. The 4U platform is augmented with a healthy dose (up to 64 GB) of DDR-based cache in an effort to reduce the amount of direct read/writes necessary to the Flash media. When power is lost, the battery backups allow the unit enough time to flush the cached data (in DDR memory) to the Flash memory prior to shut down. Because it's based on Flash, the RamSan 500 can ramp up total capacity to up to 2 TB of raw data; but performance is slower than the other purely DDR-based drives (100,000 IOPS, throughput of up to 2 GB/sec, and direct-to-Flash memory latency of under 200 microseconds).
Finally, the new RamSan 440 model is also somewhat of a hybrid; but the Flash memory within it is used purely for data backup and not for direct access. Instead, a full compliment of DDR2 memory is used for primary storage, and as such, the 4U 440 boasts performance of 600,000 IOPS and 4,500 MB/sec throughput. (Latency is less than 15 microseconds.) The 440 ships with two 4 Gb/sec FC ports standard (up to eight possible) with no InfiniBand option listed as of this writing. Capacities for the RamSan 440 are listed from 256 to 512 GB.
Key optional features for the RamSans include:
- Active Backup, which continuously backs up data to the non-volatile memory during normal operation so as to reduce the amount of time needed to shut down the drive when necessary (since only data that had not yet been committed to non-volatile memory needs to be saved). The vendor notes that the Active Backup process uses only available internal bandwidth of the device (I.E., bandwidth not used by actual applications). Without Active Backup, the entire contents of memory would need to be saved to non-volatile storage during shut-down.
- IO2, also known as Instant-On Input-Output, which allows applications to access data directly from the non-volatile Flash storage while the drive is initializing (I.E., while the data is being copied from non-volatile to DDR-based storage). IO2 is available only with the new RamSan 440.
The RamSan product line is available now, with pricing starting at $25,000 for the RamSan 300. Visit the vendor's Web site for further information.Author: EITPlanet Staff
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