The Stream File Systems
A stream file is defined as a sequence of bytes that can be accessed randomly without any additional structure added by the system used. These stream files enable the integrated file system to provide enough support for the storing and operation of the information. The folders usually available in one’s server where the documents are stored are the stream files we are referring to. A system object which has STMF as the object type is an integrated file stream systems stream file.
For each stream that is associated to a file it must have its own actual size, which is the number of the bytes that are be used by a caller; own allocation size, which refers to the amount of disk space usually reserved for a given stream and also its own valid data length, which refers to the number of bytes that are initialized based on the allocation size of a given stream.
The stream file systems are best used for storing a customer’s information such as pictures which are usually formed by continuous string of bits showing different variations of color. Other types of data stored by the stream files are videos, text in a document and audios unlike for the record-oriented files that are specifically structured for the storage of statistics such as names of persons, the account balances and addresses. These files are only accessed using the extensive programming facilities provided by a server.
The stream files take two formats: TYPE1 stream file and TYPE2 stream file. The format used depends on; first is the release that the file was created on and secondly is if the given file was created in a system that was user-defined, meaning that the value specified on that specific file system.
The TYPE1 type of stream file has a minimum and maximum size of 4096bytes and 256 gigabytes respectively. It has the same format as that of the stream files that were created on the releases before the version 4, release 4 of the OS/400.
TYPE2 type of the stream files is new in the version 4; release 4 of the OS/400 and it has high performance in file access. It can also do memory mapping and has the ability to optimize an attribute to the main storage allocation. Unless a file is made from a user-defined system, any other that is created with the V4R4 or any other newer system, all are the TYPE2 stream files. It has a maximum size of 256 gigabytes.
Microsoft Streaming File System I/O is the component that provides the required support for the file systems. It supplies the Microsoft streaming file system in form of the msfsio.sys file.
NTFS has several file stream systems types which include; the $attribute list, the $Bit Map, $Data, $EA (extended attribute data), the $EA Information, the $Index allocation, the $File name, the $Index root, the $Logged Utility Stream, the $Object ID and the $Reparse Point.
In the NTFS file system, the stream types are usually internal, meaning that the users can only open the existing NTFS file types and cannot create new ones. The naming of stream type specifier values starts with a dollar sign. The opportunistic locks and sharing modes are usually maintained for each stream.