June 21

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AS400 DLS vs. IBM i IFS – What is the difference?

By NickLitten

June 21, 2021

IBM i, IFS

AS400 DLS vs. IBM i IFS

  • Do you work at a company that has people using the AS400 DLS?
  • Do you work at a company with techies talking about the iSeries DLS?
  • Do you work at a company that uses the IFS and the DLS?
  • Are you confused about if your business server is an AS400 an iSeries or an IBM i System running IFS or DLS?

If you answered YES to any of these questions then I’m not surprised you’re confused!

Sadly ,there are still a handful of people in the both the technical and business worlds that use the wrong names for (1) your IBM i Power System and (2) software running on your IBM i System.

I’ve blogged and vented for years about the idiots (hashtag pulling no punches) who incorrectly call their IBM Power System a 1980’s AS400 or a 1990 iSeries because they like people to think the company is running a pre-internet black box with magical powers. You are NOT running an old AS400 or iSeries machine at your business. These machines were replaced decades ago. Sadly, a segment of the gray haired, sandal wearing, hippie programming brigade don’t like to move with the times and refuse to acknowledge the existence of the internet, touch phones and the death of the VHS tape recorder. These are the people that call their IBM i Systems “the 400” or “the iseries”. They also call NetFlix “VHS in the sky”. #numpties

Me. Venting. I haven’t had breakfast yet and may be feeling a little hangry.

Now that I’ve got that rant over, let’s clean this up, correcting a few wrongs and explain the differences between IFS and DLS in simple terms:

IBM i has an Integrated File System (IFS), which extends the operating system interface to use a Microsoft windows based file system with all standard windows style sharing/security. This also opens up the IBM i file structure to be easily accessed by any APPLE or LINUX system. Along with SQL this lets just about any other system interact with data directly stored on IBM I without having to use an interface system!

Simply Put : The IFS lets the IBM-i System share its data just like a Windows Server does

So, where does the DLS fit in?

Thirty years ago, before Microsoft Windows was invented, IBM’s early machines (AS/400’s) had a DOS based file sharing system called DLS (Document Library System). This allowed us AS/400 programmers to copy IBM data into this DLS area, using DOS file name format, sharing the data with any DOS machines on the network.

This was the early days of networking and one significant drawback was that DOS has no file level security and limited to 8-3 file names. The only way to secure a file share was to add a username/password to the share location itself.

I wrote a blog a few years back describing the difference between IFS and DLS like this:

You may read about IBM i IFS and also QDLS. It can be confusing for people, if you haven’t used IFS or DLS.

My simple explanation is think of DLS as the OLD DOS way of storing PC files and IFS as the new Windows (or Apple) way. Think old short file names like MYDOCUMENT.DOC versus the new naming standards like “Christmas Shopping List 2017.doc”

The DLS is a vintage, subset of the IFS.

The QDLS folders were orig created for OfficeVision, a discontinued product, but can (and have been) used for other purposes. These folders are DOS-compatible and therefore use DOS style name (8.3 format). Directories (as sometimes called folders) not under QDLS are Unix compatible – long filenames and case-sensitive.

That sounds complicated but to make it very simple

IFS | Windows Style – Windows File Sharing of data from IBMi. Long Windows File names. Links to data might look something like this \\systemname \home \stuff \Big_Report_of_stuff.pdf

QDLS | DOS Style – Dos based File sharing. Short xxxxxxxx.yyy file names. Links to data might look something like this \\systemname \qdls \nickstuf \bigreprt.pdf

What is the Integrated File System (IFS)

file system provides the support that allows applications to access specific segments of storage that are organized as logical units. These logical units are files, directories, libraries, and objects.There are seven file systems in the integrated file system:

  • root(/) File System

The root (/) file system is designed to take full advantage of the stream file support and hierarchical directory structure of the integrated file system. It has the characteristics of the WINDOWS, DOS and OS/2 file systems.

  • Open Systems (QOpenSys) File System

The Open Systems (QOpenSys) file system is designed to be compatible with UNIX-based open system standards, such as POSIX and XPG. Like the root (/) file system, it takes advantage of the stream file and directory support provided by the integrated file system. In addition, it supports case-sensitive object names.

  • Library (QSYS.LIB) File System

The library (QSYS.LIB) file system supports the IBM® i library structure. It provides access to database files and all of the other IBM i object types that are managed by the library support. The QSYS.LIB file system maps to the IBM i file system. For example, the path /qsys.lib/qsysinc.lib/h.file/stdio.mbr refers to the file member STDIO, in the file H, in library QSYSINC, within the root library QSYS.

  • Document Library Services (QDLS) File System

The Document Library Services (QDLS) file system supports the older DOS based folder and file objects. It provides access to documents and folders.

  • LAN Server/400 (QLANSrv) File System

The LAN Server/400 (QLANSrv) file system provides access to the same directories and files that are accessed through the LAN Server/400 licensed program. It allows users of the IBM® i file server and IBM i applications to use the same data as LAN Server/400 clients.

Files and directories in the QLANSrv file system are stored and managed by a LAN server that is based on the OS/2 LAN server. This LAN server does not support the concept of a file or directory owner or owning group. File ownership cannot be changed using a command or an ISO stream I/O function and system API. Access is controlled through access control lists. You can change these lists by using the WRKAUT and CHGAUT commands.

  • Optical Support (QOPT) File System

The Optical Support (QOPT) file system can be accessed through the integrated file system interface. This is done using either the IBM® i file server or the integrated file system commands, user displays, and ISO stream I/O functions, and system APIs.

  • File Server (QFileSvr.400) File System

The File Server (QFileSvr.400) file system can be accessed through the integrated file system (IFS) interface. This is done by using either the IBM® i file server or the integrated file system commands, user displays, and ISO stream I/O functions and system APIs. Note: The characteristics of the QFileSvr.400 file system are determined by the characteristics of the file system that are being accessed on the target system.

AS400 DLS vs. IBM i IFS - What is the difference? 1

Using IFS functionality means applications on other file systems, Linux, Apple, PC, Unix, etc., can easily access data stored on your IBM i System as a network drive. This Network drive, shares the IFS contents just like a Windows Server File share. The IFS provides access to the data inheriting industry standard security, data encryption and file share flexibility.

DLS is subset of the IFS in old DOS format mode. It only supports old eight character file names. It has never heard of the internet. It smells lightly of stale beer and cigarettes. Just like your Uncle Jake who always gets drunk at weddings and waffles on about the “Good Old Days”.

Don’t use the DLS –Simply create and use a new IFS location.

Upgrade yourself to the 21st century.

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