Configuring the CSB Core Laptop for Synchrotron Trips

This document gives an overview of how and why the Core laptop is configured. For detailed installtion instructions, see: http://www.csb.yale.edu/synchrotron/laptop-install.html.

There are two primary purposes for configuring a laptop computer for use on synchrotron trips. They are 1) transporting data and 2) processing data.

Transporting Data -- Overview

Data has been transported from synchrotrons via internet and via tape. Both of these methods can be slow, and tape must be successfully read on return to the CSB.

Recent advances in disk technology have made it practical and affordable to transport the entire result of a synchrotron trip on one or two disk drives.

We have chosen to use the IEEE-1394 (firewire) disk drives from Maxtor, along with their 1394 PCMCIA interface card. At this writing, they are available in 60GB and 80GB capacities. Although SCSI drives are available in much higher capacities, these Maxtor drives come in relatively transportable enclosures, and the cabling is easier.

Processing Data -- Overview

Data is processed using the HKL2000 suite of programs. These are installed on the laptop in /usr/local/bin, with the license file in /usr/local/lib.

User Management

Each user may have their own account on the laptop. In addition, there is a common account that all users may, and probably should use when downloading data at the synchrotron. The common account should ease file management, at the expense of making each user less secure against errors or malice from co-workers.

Linux vs Windows vs MAC

With the growing availability of IEEE1396 (firewire) disks, it might seem logical to use Windows, or a Macintosh, both of which offer good support for these devices. In each of these systems, a user is able to hot-swap disk drives, making it easier to bring multiple user disks to bear on the project.

Linux, on the other hand, offers rudimentary support. It requires a certain amount of hand-waving, incense-burning and other tools of wizardry to carry off successfully.

But the data processing software runs under Linux. If we are to process data on the laptop, as well as transport it, we must be able to access the external disk.

Configurations

The synchrotron laptop is unusual because it must have three different configurations of the operating system.

1. DHCP-based system for downloading data at synchrotrons
2. Standalone system for processing data anywhere
3. CSB system for use in the CSB Core

To achieve this, we have multiple root partitions on the hard drive in the laptop. All root partitions use the same /usr, /tmp and /home partitions, as well as sharing access to the Maxtor disk mounted on /frames. At boot time, the LILO loader offers the user the opportunity to choose which root partition to boot.

DHCP-based system for downloading data at synchrotrons

This configuration is the default at boot time, and is labelled Synchrotron in the LILO loader. With this option, the computer uses DHCP to acquire a network address. Under this scheme, the system broadcasts a message on whatever local network it is connected to. A DHCP server on the network (if there is one) replies, giving the laptop a network address and other network parameters. Using this scheme, the laptop should be able to communicate with other computers at the synchrotron.

Unfortunately, the laptop cannot run the data processing programs in this mode.

No user accounts have been added to this system, except for the default data collection account.

Standalone system for processing data anywhere

The HKL2000 data processing suite requires a valid license to run. The license is tied to the network address of the licensed computer. So the license for xanthippe, the CSB laptop, is tied to a specific network address that it uses in the CSB Core.

Therefore, there is a second boot partition (labelled Core in the LILO loader), that configures the laptop for the licensed network address.

Outside the Core, this network address will not allow communications with any other computers, so the laptop is effectively stand-alone, and should be disconnected from the network. However, the HKL2000 license should be valid.

This system has user accounts, as well as the default data collection account. Either can be used for offline processing of data.

CSB system for use in the CSB Core

For full functionality in the CSB core, there should be a third root partition. This would bind to the Core's NIS domain and provide the same user environment as other Core linux computers.

This partition has not been installed, and probably will not, save by loud popular demand. The standalone system can be used in the Core as well. From "standalone" system, if it is connected to the Core network, the user can mount /srv/frames or use ftp to upload files from the laptop disk to the COre servers.