CISL Annual Report 2005 > Production cyberinfrastructure accomplishments

Mass Storage System (MSS) accomplishments

NCAR Mass Storage System (MSS) growth continued in FY2005. Projections and trends at the beginning of FY2005 indicated a continual exponential growth path. While this growth has been manageable in the past, it has been recognized that it may not be economically sustainable into the long-term future. Major accomplishments in FY2005 address the continued MSS growth and investigate methods of managing this growth into the future.

A slight reduction of MSS growth was seen at the beginning of FY2005 as indicated in the figure below. This reduction was short lived as the growth rate picked up again in the latter part of the fiscal year. The red line is an exponential trend line.

The Mass Storage System is growing at an exponential rate.

Storage capacity and data delivery capability were enhanced in FY2005. FY2004 saw the integration of the StorageTek 9940B tape technology into the NCAR MSS. This technology provides a 3.3 times increase in storage density and a 3 times increase in data transfer rate over the StorageTek 9940A technology and a 10 times storage density increase over the StorageTek 9840A technology, both of which were deployed in the MSS. Additional 9940B tape drives were installed in FY2005, which enabled the placement of second copies into the StorageTek 9310 Automated Cartridge Subsystems (robotic tape silos) and reduced the number of manual mounts to near zero. Previously second copies were written to manually mounted 9940A tape drives. The widespread deployment of the 9940B tape drives enabled the migration of the existing MSS data to the new technology. In FY2005, all silo-resident 9840A data (~250 TB) were migrated to the 9940B technology and the migration of the 9940A data (~1,500 TB) was started.

Data delivery capability will be enhanced in FY2006 with the expansion of the MSS internal disk cache. The disk cache holds newly written data and frequently accessed data. The disk cache will be expanded from 11 TB to a total of 44 TB. A Serial ATA (SATA) disk evaluation project was completed in FY2005. SATA is a lower cost option to Fibre Channel disk that is just emerging in the high-end storage arena. However, the characteristics of SATA disk do not allow it to be a complete replacement for the enterprise-class Fiber Channel disk. The evaluation project concluded that SATA disk was an option for the MSS disk cache. The SATA disk was purchased in late FY2005 and targeted for full deployment in early FY2006. The expanded disk cache will reduce data delivery response time because access to data in the disk cache is much faster than data on tapes. The size of the disk cache will be monitored on a regular basis and expanded as needed to maintain minimal response times.

The Mass Storage Control Processor (MSCP) supports many of the core NCAR MSS processes including the metadata database and resource allocation. The MSCP was upgraded in FY2005 in anticipation of an increased MSS workload and to provide a platform on which MSS server consolidation can be evaluated. The MSS is experiencing an increase in the number of servers it uses internally to provide the archive service. The MSCP replacement supports multiple Linux images on the same hardware platform. A future project will investigate the feasibility of consolidating the MSS servers on the MSCP from both economical and technical perspectives.

Finally, a project to address MSS growth was initiated in FY2005. Over the years, SCD has observed a direct relationship between the computational capacity at NCAR and the net growth of the MSS. Future NCAR computing projections indicate a potential 25-fold increase in capacity. SCD will evaluate and create a strategy to address the MSS capacity increase with the intent to accommodate growth with minimal budgetary increases. Some adjustments have already been made in FY2005. Those being the elimination of many duplicate copies after consulting with the owners of the data and reducing the amount of system backup data stored in the MSS. The result of those efforts is indicated in a smaller total growth of the MSS in FY2005 than the trend had indicated.