Specifications

Image
R
⃝
PCI-E (“PCI express”) 1x external SATA-II adapter based on the SteelVine
TM
series of
storage controllers is added to the stock system. The eSATA adapter came packaged with the Venus-
T5
TM
RAID enclosure. The enclosure contains five hot-swappable Seagate 1 TB 7200 RPM SATA-
II hard disk drives, and provides a total storage capacity of 5 TB less file system and formatting
overhead. This is the configuration that has been implemented and verified.
An alternative to the Venus-T5 enclosure being considered for the delivered version is a rack-
mountable 1U SATA II enclosure. This option would reduce the server rack space required for the
MCS-DR, and would facilitate easy removal and replacement of data storage while keeping the drives
together. Testing of this option is will begin shortly.
The MCS-DR PC’s high speed Ethernet interface is a Myricom
R
⃝
model 10G-PCIE-8A-C+E 10
gigabit Ethernet adapter. The adapter is a PCI-E 8x adapter which connects to the network via a
10GBase-CX4 physical interface. The cables used to connect the MCS-DR PC to the DP subsystem
are Myricom
R
⃝
10G-CX4-1M 10GBase-CX4 copper cables.
2.2 Software Brief
The MCS-DR PC software is a BSD-Sockets based Linux application operating in a polling paradigm.
The software is written in ANSI C, and is a single process, though interacting with the host com-
puter requires short-lived child processes in a few instances. The software uses the Posix.1b real-time
extensions library (librt
1
) for asynchronous transfers to and from disk, and for queuing messages
from MCS. Figure 2 illustrates the organization of the software and outlines the scope of the ap-
plication within the MCS-DR PC. The operating system is Ubuntu Desktop 9.04 AMD64. The
main processing loop of the application polls a socket for command messages from MCS. Upon
receiving commands to start a specific operation, the main lo op enables components of the data
path necessary for receiving data from the network, writing data to disk, reading data from disk,
and transmitting data to the network. The main processing loop then checks each portion of the
data path to see if action is required to move data along, taking action where necessary. Once an
operation is complete, the data path is disabled and the system is returned to the idle state, making
it available for future operations. To interact with the host computer and operating system, the
software contains functions which gather environment and machine status information such as CPU
and hard drive temperatures, free disk space, and so forth, as well as functions to format the drive
array, mount partitions, and perform general maintenance functions.
1
Documentation available online at http://compute.cnr.berkeley.edu/cgi-bin/man-cgi?librt+3
5