It has been well over a year since we expanded the VLBA's Mark 5 recording media pool. The primary limitation has been problems in support of the newer, serial-ATA (SATA) interface rapidly being adopted by the disk-drive industry. We have deferred procurement of new SATA drives until these were resolved, and it has become difficult recently to buy drives with the older, parallel-ATA interface.
We believe this logjam has finally broken, as a result of recent tests and fixes by Conduant Corporation, in collaboration with NRAO and Haystack Observatory, in both hardware and software. We recently ordered new Mark 5 modules with a total capacity of 180 TB, which will increase the VLBA media pool to about 750 TB, 32% larger than what we have been using since mid-2007. This expanded media pool is expected to accommodate significantly more observing at both 256 and 512 Mbps.