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High-Bandwidth, Low-Latency, I/O Solutions
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The RAM-SAN Evolution
This article describes the general development of the storage area network (SAN) and its derivative, the RAM-SAN.  The RAM-SAN is a SDRAM based SAN element with a greatly reduced latency as compared to disk based SAN elements.  Texas Memory Systems manufactures a RAM-SAN, called the SAM-500.  It has a 64 Gbyte storage capacity, an available aggregate I/O bandwidth of 2.8 GB/sec, and up to 15 Fibre Channel ports.  The SAM-500 scales with both storage and I/O bandwidth.
   
RAM-SAN Applications
This article describes RAM-SAN applications.  A typical RAM-SAN application is one in which speed is the ultimate requirement.  Whether your SAN has transactional databases, data warehouses, shared storage, or streaming media and internet caching, the RAM-SAN can provide the very low latency and high bandwidth capabilities that you need.
  
The SAM-500 makes for an ideal RAM-SAN.
The SAM-500/520 systems have been designed from the ground up to perform as an ideal RAM-SAN.  High bandwidth and very low latency are the main features of the SAM-500/520.  This is accomplished with the use of a fast access SDRAM based memory.  The SAM-500 has a storage capacity of 32 Gbytes and the SAM-520 has a storage capacity of 64 Gbytes.  Both SAM systems include 15 Fibre Channel I/O ports that operate at full speed.  Each Fibre Channel interface includes special hardware to reduce latency and speed up access time.  With this awesome capability, the SAM-520 can easily fulfill all current access requirements and still have a wide margin for growth.  
  
One technique for removing the limitations of disk-based storage is to replace the disk drives with RAM-SAN - a fast-access synchronous DRAM (SDRAM) - as the basic storage media.  While this method is costly, it can dramatically improve SAN performance under worst case conditions.  With the RAM-SAN, latency is virtually eliminated and data access is immediate.  The RAM-SAN architecture also allows for many high-bandwidth I/O ports, each supporting simultaneous random access.  The power of the RAM-SAN is its ability to access random data quickly and independently of the previous data access.
  
The RAM-SAN removes the time critical I/O bottlenecks inherent to RAID-based storage devices.  With SDRAMs, data retrieval is virtually instantaneous.  Ultra low latency performance is maintained (<10 microseconds) across a wide range of operating scenarios -- accessing short files, long files, random files, or shared files. Traditional SAN rotation drives get progressively slower as more computers attempt to access the SAN.  The RAM-SAN gives your computers immediate access even under maximum load conditions.
  
While the RAM-SAN only requires a modest 10.5" of rack space, it still provides more effective bandwidth (3 Gigabytes/sec.) than refrigerator-sized cabinets of disk arrays.  This available bandwidth provides an easy growth path or on-demand extra capacity for special requirements.  The RAM-SAN can be expanded to a memory capacity of 64 Gigabytes and an I/O capability of 15 Fibre Channel ports operating at full speed.
  
The RAM-SAN delivers 500,000 I/Os per second to your applications.  Store your OLTP database on the RAM-SAN and you will see instant and dramatic improvements in application response time.  If your ERP system is facing storage bottlenecks, the RAM-SAN can be used to open up the I/O floodgates.  The RAM-SAN also accelerates database "hot files" access.  Data warehouses with heavy user access, complex queries, or fast load requirements exhibit screaming performance improvements with the RAM-SAN.
 
Plug and Play
The RAM-SAN comes with a standard factory configuration allowing the user to attach it to their Fibre Channel fabric and have instant access without requiring any additional configuration.  The RAM-SAM connects to an existing network via one or more Fibre Channel (FC-21) interfaces which attach directly to the ports of a Fibre Channel switch or to servers providing Fibre Channel connectivity.  Dedicated links may be reserved for demanding workgroups and users, thus providing the ultimate in SAN performance.  Once attached to the Fibre Channel network, each Fibre Channel HBA driver should automatically detect the RAM-SAN's presence.  The SAM-500 may then be accessed like any standard storage resource on the network, only much faster.  Each FC-21 connection may be individually configured to permit unrestricted global memory access or to limit its permissible access to a subset of the overall system memory.