4.2

RAW File

The RAW file format has been for many years the primary data format of the ISIS facility.

Structure

The Raw file is a binary formatted file that uses a simple but effective compression system to achieve 4-1 compression of the data in holds.

Compression

To be completed later

Alternate Data Streams

When the Raw file is archived to the NTFS archive additional information about it is added as an Alternate Data Stream. This includes a list of all of the files that were archived with this RAW file and a checksum for each. This can provide a fast way of finding the log files associated with a RAW file in a crowded directory.

For example:

d28cb560cdefc765fc8d550b6f335006 *SANS2D00000799.log
52526cd14652284c2748e905ff74fc4b *SANS2D00000799.nxs
7d3b5776c32b63aa76b9e36d2e7ec348 *SANS2D00000799.raw
de230169cda344118d26315dd31c0fb4 *SANS2D00000799.s001
cbd0685b6ce19781fca13ba4395318d9 *SANS2D00000799.s01
f9b9aa805179598207d6bf713eacd5a7 *SANS2D00000799_Beam_Shutter.txt
d10238be18d69d21f8890f73805795bb *SANS2D00000799_Changer.txt
acc92b1223bb93ad85e03b523639142a *SANS2D00000799_Fast_Shutter.txt
671d77b4d2d9a1deee3e6dc9c3db9875 *SANS2D00000799_Height.txt
2eb44a65f79f73e194cdcd48d38385b4 *SANS2D00000799_ICPdebug.txt
0268e471a0ae4c0382ffb81622e03dde *SANS2D00000799_ICPevent.txt
3cda6c3f179c6f70fea82e9ad9e75360 *SANS2D00000799_ICPstatus.txt
19ea5cbe0e57b01db61b01ba24f70bc5 *SANS2D00000799_Julabo.txt
2e6bb0fe5965527d1cb319fff0df928d *SANS2D00000799_Moderator_Temp.txt
604946b7385f8d08ff9c9eb47b0803c2 *SANS2D00000799_Sample.txt
cf5022506705b6ba5c850edd824088be *SANS2D00000799_Status.txt
54e4a8e82fe00cd5e9263bb14506682f *SANS2D00000799_Table.txt

In the links below you will streams or DIR on Vista can list the streams on a file. Not many programs can display the contents of an alternate data stream, but so far I have discovered that the following work, at least for RAW files.

notepad2.exe SANS2D00000799.raw:checksum
more < SANS2D00000799.raw:checksum

If a file with an alternate data stream is copied to an FAT file system the alternate data stream is lost. It has been reported that if a file with an ADS is copied using SAMBA to a unix file system the streams are extracted into separate files with automatically generates suffixes.