ReadSCSI is a fast, efficient, minimal interaction tool for transferring data from a SAM or DFD format SCSI disk into a PC filesystem. As such, there is minimal control or configuration of the recording parameters, optimising instead for speed.
There are two modes of operation, either transfer entire disk, or select streams and time-windows.
The program is self contained, and stand alone. It does not need any explicit installation, and can be run as is.
When run, ReadSCSI will scan all scsi interfaces and devices until it finds a non-dos disk drive. It then reads the SAM format FAT table, and displays the ID of the SAM which recorded it in the title bar.
The default recording options are read from the current Scream settings file (if found). These can be modified as necessary, but will not change the underlying Scream settings. For details on File Duration, filename format and Base Directory, see the recording options in the Scream help. At this time, GCF, miniSEED, SAC (intel or motorola order), SUDS, GSE and SEGy (intel or motorola order) data formats are available.
To select individual streams for transfer, or to limit the data time, click the 'specify transfer parameters' button, and select as necessary. To select more than one stream to transfer, simply hold the CTRL key whilst clicking on the stream names.
The 'Transfer all SAM disks' option is provided to allow unmanned transfer of all the SAM disks connected to the computer. This is useful in a multi-disk tower unit, where many SAM disks can be loaded and transferred with two mouse-clicks. ReadSCSI will sequence through all the disks and SCSI interfaces on the system, transferring any that are identified as SAM disks. For example, with a PC with two SCSI busses, and 4 disks on each bus, the user could load 8 SAM disks, and transfer them in one operation, by checking this box and pressing 'Start'. The user is responsible for ensuring sufficient storage capacity on the target drive for all the data.
This option is only available when the entire contents of the disks are being transferred, as different disks will have different data streams, and/or different time spans.
To see a detailed table representation of the SAM FAT, use the /showfat parameter when starting ReadSCSI. The output is similar to the DIR command for the SAM unit.
This operation will mark the current SCSI disk as being 'reset', and ready for use when next fitted to a SAM unit. Note that it does NOT format the disk, or erase the contents or FAT. (It actually sets the ID to zero). The disk is still readable until next written to by a SAM unit.
The reset disk function will NOT attempt to reset a DOS formatted disk, nor re-reset an already reset SAM disk. Attempting to repeat a reset operation will generate a message indicating these points.
ReadSCSI will attempt to load ASPI drivers for communicating with disk devices. On Windows NT (and system that use NT style disk subsystems, like 2000 and XP), if the ASPI layer is not found, then it will attempt to read the disks using NT style semantics. This mode requires ReadSCSI to be run with Administrative permissions (ie the user is logged in as administrator).
Under Windows 95, the SCSI driver will only start up during boot if a SCSI device is found. This means that in order for ReadSCSI (or scream) to see a SCSI disk, a disk (any disk) should be fitted and powered up on the SCSI chain during windows boot. After the boot is complete, the disks can safely be swapped without subsequent re-boots. (Some older SCSI cards e.g. Rancho are not suitable for hot-swapping of the disks, and will crash the system).
This is not a problem under Windows NT. If you are running ReadSCSI on NT (or above), and do not have an ASPI driver installed, you should use the Device Manager to ensure that the system recognises the disk drive (using "Refresh" as necessary), before running ReadSCSI. Likewise, you should close ReadSCSI before removing a SAM disk, otherwise the system will report that a re-boot is necessary.
An ASPI driver is installed as standard on Windows 95 and 98. It is not installed for NT. You should obtain a suitable ASPI driver if necessary from your SCSI card manufacturer (eg Adaptec's WinASPI).
By default, ReadSCSI issues a command to the system to rescan the SCSI bus for new devices. This is required in some variants of Windows in order to detect a hot-swapped disk. On some Windows platforms, however, this might cause a fatal crash of the system (blue screen). If this is a problem, use the command-line parameter /NORESCAN to prevent this rescan operation. You may have to re-boot the computer with the SAM disk inserted in order for the operating system to recognise the presence of the disk.
There is a significant difference in the way that Scream reads
the SCSI disk to the way ReadSCSI operates:
ReadSCSI is designed to transfer the whole disk, and as such
reads the disk sequentially block by block. Scream is designed
for stream replay, so follows the 'chain' of a stream.
This means that whereas Scream simply follows the 'chain', ReadSCSI actively validates the chain as it reads through the disk. Any errors in the chain, disk contents, or data gaps are detected and logged in a file, stored in the 'Base Directory', with the stream name as a file name.
For optimal transfer rate, a destination filesystem should use FAT or FAT32. Avoid NTFS, as the overheads involved in this filesystem can significantly slow down file-intensive transfers like ReadSCSI.
| SAM | Storage and Acquisition Module |
| FAT | File Allocation Table |
| SCSI | Small Computer Systems Interface |
| GCF | Guralp Compressed Format |
| SAC | Seismic Analysis Code |
| SUDS | Seismic Unified Data System |
| SEED | Standard for the Exchange of Earthquake Data |
| GSE | Group of Scientific Experts |
| SEGy | Society of Exploration Geophysicists Y format |