HP ARPA File Transfer Protocol User's Guide (36957-90159)

Chapter 6 61
MPE/iX File System and Data Transfers
MPE/iX File System
All files in the set beginning with letter “P” are created with the following attributes: file
code label PROG, fixed binary, 128 word records, and a maximum number of records equal
to 1,023. The blank space preceding the semicolon is required.
The third example shows a remote user transferring a file from their system to an MPE/iX
system using BUILD parameters as follows:
ftp> PUT myfile MPEFILE;Rec=-256,1,F,BINARY;DISC=11000;CODE=PROG
An MPE/iX fixed binary file named MPEFILE is created with records of 256 bytes, with a
maximum record size of 11,000. The file code label is PROG.
MPE/iX File System
The MPE/iX file system is record oriented. Each file has a file limit (DISC parameter in
BUILD) which determines the maximum number of records the file can hold. Each record
has a maximum record size which indicates the maximum number of bytes each record can
hold. In addition, a file may have fixed or variable length records.
Typically, variable length records are more efficiently stored on the system, and less
efficiently accessed. For fixed length record files, storage on the system is less efficient
because of byte padding, and access is faster because the records are all the same size.
Fixed Record File Padding
Files created on MPE/iX with fixed records may result in the padding of the records to the
record size specified. ASCII files are padded with blank spaces, and binary files are padded
with zeros.
For example, a file named vfile containing variable length records is transferred to an
MPE/iX file as follows:
ftp> ascii
ftp> get vfile fixfile
The default file building parameters for ASCII transfers is fixed records of 80 bytes in
length. The resulting file will be stored with 80 byte records. Records from vfile that
contain fewer bytes of data will be padded with spaces.
Record Truncation
Record truncation can occur when performing a data transfer to an ASCII file on the
MPE/iX system. This occurs when the number of bytes in the data transfer exceeds the
maximum record size bytes in the target file. When this occurs, the target record is filled to
the maximum record size bytes from the data transfer, and the remaining bytes for the
current record are discarded. A warning message is displayed when this occurs.
For example, a file named zfile containing 132 byte records is transferred to MPE/iX as
follows:
ftp> ascii