Mark 6

Mark 6 VLBI Data System

The Mark 6 system is being developed by Haystack Observatory as a 16 Gbps next-generation disk-based VLBI data system based on high-performance COTS hardware and open-source software.

Mark 6 system goals:

16Gbps sustained record and playboack capability
32Gbps burst-mode capability
General Ethernet packet recorder
(can be straight-forwardly adpated to other interfaces as well)
Based on inexpensive high-performance COTS hardware
Easily upgradeable on Moore's Law curve
Linux OS (Debian Squeeze 6.0.3) with open-source software
Playback as standard Linux files
VLBI Disk-Adaptive Format (VDAF) file system to manage slow and failed disks
Compatible with e-VLBI data-transfer requirements
Smooth transition from Mark 5
Preserve as much investment in existing Mark 5 systems and disk libraries as possible
Extensive stress testing in real-world operational environment

The Mark 6 will flexibility support recording from 8 to 32 disks; a new disk-management system is being developed to flexibly support this capability. The Mark 6 M&C system is based on the VSI-S protocol.

In order to preserve as much investment as possible in existing Mark 5 systems and disk modules, Haystack Observatory is collaborating with Conduant Corporation in the design of the Mark 6 chassis and modules; all software is being developed by Haystack Observatory. Existing Mark 5 SATA modules will be upgradeable to Mark 6 compatibility with an upgrade kit consisting of a new module backplane with a new high-reliability power connector at the rear and a new front panel with connections for two SAS2 data cables. and front panel; Mark 6 systems will use the same bare chassis as Mark 5, and existing Mark 5 chassis will be upgradeable to Mark 6 compatibility by replacing all electronic components.

Prototype Mark 6 systems were used in October 2010 in a 16 Gbps demonstration VLBI experiment between Westford Observatory and NASA/GGAO Observatory, followed by successful correlation on the Haystack DiFX correlator.

The Mark 6 system is projected to be available for general VLBI use in mid-2012.

Haystack Observatory also gratefully acknowledges the continuing support of the NASA/GSFC High-End Network Computing Group for consultation on high-performance COTS hardware that have greatly helped in the rapid development of Mark 6

For a more complete overview of the Mark 6 system, see the Mark 6 memo series, including a presentation at the Dec 2011 DiFX workshop.

For additional information on Mark6 please visit: www.vdas.org for general information and code.vdas.org for code repository..

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