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Close up of a section of the disk arrays
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The South African Earth Observation Strategy (SAEOS) entered a second phase when its storage array network (SAN) was commissioned during June 2008 at the CSIR Satellite Applications Centre. This central product library stores both raw remote sensing data and processed data. Its 4Gbit/sec fibre connection ensures a high level and volume of data transfer and production.
“In practice, this means that it is possible to archive, process and serve very large volumes of remote sensing data automatically and efficiently to improve the CSIR’s quality of service to government and private sector clients,” comments Alan Caithness, the systems engineer responsible for overseeing the commissioning of the SAN.
The storage system consists of Silicon Graphics (SGI) InfiniteStorage arrays, a Spectra T950 robotic tape library, a high-performance SGI Altix 450 server and associated fibre channel switches. The storage arrays are divided into 28 terabytes usable primary storage using high-performance 15 000 revolutions per minute fibre channel drives and 55 terabytes usable second-tier storage using standard performance 7 500 revolutions per minute SATA (serial advanced technology attachment) drives.
The tape library can accommodate 720 LTO4 (linear tape-open) tape cartridges each with a capacity of 800 gigabyte uncompressed data. This gives a total capacity on tape of 550 terabyte and hardware compression can increase this to over 1 petabyte, depending on the type of data stored.
Hierarchical storage management is provided by the SGI data management facility software. This automatically manages migration of data files from high performance disks to second-tier standard performance disks to tape. If a file exists on tape only, the system will transparently restore the file to disk.
The SGI cluster file system CXFS, which is a distributed networked file system, makes files on the SAN fully shareable by all servers connected to the SAN, which may be running different operating systems, such as Linux, Unix or Windows. The read/write performance over the SAN is generally faster than read/write to a local disk on a server. Through CXFS the files on the SAN can also be accessed and shared by any other computer on the local area network, using a NAS (network attached storage) connection.
The equipment was funded by the Department of Science and Technology and supplied by African Business Intelligent Solutions (ABIS).
For more information, contact Alan Caithness
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