SATAnet operating modes

Contents
1 » Default mode3 » Circuit-switched mode
2 » Packet-switched mode4 » Distributed storage mode
Default mode
  • Operates as a normal local SATA disc.

The SATAnet router appears as a normal local hard disc to each node it is connected to. If the router has a physical disc installed then this disc is seen by the nodes otherwise the router appears as a blank disc.

Packet-switched mode
  • High-bandwidth network communication.
  • Co-exists with storage and filesystems.

This is the most flexible networking mode. Data is encapsulated into packets and sent from one node to another using normal SATA protocols. Specifically, reading or writing a packet is simply a case of reading or writing the relevant number and location of sectors.

Both network communication and storage access can co-exist and be freely intermixed over the same SATA interfaces and the networking does not interfere with filesystem operation.

Circuit-switched mode
  • Ultra-low latency transfers between applications.

This mode is intended for use for short periods of time between two or more nodes when ultra-low latency communication is desireable. The contents of a variable in a userspace program on one node can be transferred to a variable in a userspace program on another node in under 1µs.

Whilst in this mode, a path through the SATAnet is reserved and so general communication and storage access by other nodes will have temporarily higher latencies.

Distributed storage mode
  • Allows abstraction of storage.
  • Mount any data (e.g. the world-wide web) as a normal disc and filesystem.
  • Manipulate data with “intelligent storage” (e.g. encryption).

This mode co-exists with the other modes and allows SATA commands to be transferred elsewhere for processing, effectively allowing a processing node (normally a SATA host) to behave as a SATA device.

This is a very flexible mode as it allows complete abstraction of any data storage and present it through the SATA interface. For example, the entire world-wide web could be made available and mounted as a sub-directory, e.g. as /mnt/www with websites accessed as local files.

Similarly, “intelligent storage” can be implemented, e.g. transparent encryption and compression, RAID, on-site/off-site backups, etc.

Other benefits include: large (and fast) swap files on discless nodes; secure swap files — the underlying storage medium is abstract and not contained within the node; memory can be easily shared amongst nodes by mapping it to a block of sectors or file.

Technology in brief

A cluster communication interconnect which can be utilised without special drivers by any platform which supports Serial ATA connectivity regardless of architecture and operating system.

The unique approach also offers “centralised distributed” storage, allowing a physically remote disc to be accessed as a local disc — reduces heat, noise, and vibration, improves cooling, and removes points of failure within cluster nodes.

Technology reports


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Function


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Operating modes

Performance


Networking characteristics

Storage characteristics

Related technology


Cortica

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