Integrated File System Introduction

File system comparison

Table 4 and Table 5 summarize the features and limitations of each file system.

Table 4. File System Summary (Part 1 of 2)

Capability / ("root") QOpenSys QSYS.LIB16 QDLS QNTC
Standard part of OS/400 Yes Yes Yes Yes Yes
Type of file Stream Stream Record 12 Stream Stream
Integrated with OfficeVision (for example, file can be mailed) No No No Yes No
Access through OS/400 file server Yes Yes Yes Yes Yes
Direct access through file server I/O processor 1 No No No No Yes
Comparative speed for open/close Medium 2 Medium 2 Low 2 Low 2 Medium 2
Case-sensitive name search No Yes No 4 No 5 No
Maximum length of each component in path name 255 char 255 char 10.6 char 6 8.3 char 7 255 char
Maximum length of path name 8 16MB 16MB 55 - 66 char4 82 char 255 char
Maximum length of extended attributes for an object 2GB 2GB Varies 9 32KB 64KB
Maximum levels of directory hierarchy within file system No limit 10 No limit 10 3 32 127
Maximum links per object 11 Varies 15 Varies 15 1 1 1
Supports symbolic links Yes Yes No No No
Object/file can have owner Yes Yes Yes Yes No
Supports integrated file system commands Yes Yes Yes Yes Yes
Supports integrated file system APIs Yes Yes Yes Yes Yes
Supports hierarchical file system (HFS) APIs No No No Yes No
Threadsafe 13 Yes Yes Yes No Yes
Supports object journaling Yes Yes Yes14 No No
Notes:
  1. The file server I/O processor is hardware used by LAN Server.
  2. When accessed through the OS/400 file server.
  3. When accessed through a LAN Server client PC. Access using iSeries APIs is comparatively slow.
  4. The QSYS.LIB file system has a maximum path name length of 55 characters. See Library file system (QSYS.LIB) for details. The Independent ASP QSYS.LIB file system has a maximum path length of 66 characters. See Independent ASP QSYS.LIB for details.
  5. See Document Library Services File System (QDLS) for details.
  6. Up to 10 characters for the object name and up to 6 characters for the object type. See Library file system (QSYS.LIB) for more details.
  7. Up to 8 characters for the name and 1 to 3 characters for the file type extension (if any). See Document Library Services File System (QDLS) for details.
  8. Assuming an absolute path name that begins with / followed by the file system name (such as /QDLS...).
  9. The QSYS.LIB and Independent ASP QSYS.LIB file systems support three predefined extended attributes: .SUBJECT, .CODEPAGE, and .TYPE. The maximum length is determined by the combined length of these three extended attributes.
  10. In practice, directory levels are limited by program and system space limits.
  11. Except a directory, which can have only one link to another directory.
  12. The user spaces in QSYS.LIB and Independent ASP QSYS.LIB file systems support stream file input and output.
  13. Integrated file system APIs are threadsafe when the operation is directed to an object that resides in a threadsafe file system. When these APIs are operating on objects in file systems that are not threadsafe when multiple threads are running in the job, the API will fail.
  14. QSYS.LIB and Independent ASP QSYS.LIB file systems may support journaling different object types than the root, UDFS, and QOpenSys file systems. See the Journal management topic in the iSeries Information Center for more information about journaling objects that reside in the QSYS.LIB or Independent ASP QSYS.LIB file systems.
  15. *TYPE2 directories have a limit of one million links per object. *TYPE1 directories have a limit of 32, 767 links per object. For more information, see *TYPE2 directories.
  16. Data in this column refers to both the QSYS.LIB file system and the Independent ASP QSYS.LIB file system.

Abbreviations

char = characters

B = bytes   KB = kilobytes   MB = megabytes   GB = gigabytes


Table 5. File System Summary (Part 2 of 2)

Capability QOPT QFileSvr.400 UDFS NFS QNetWare
Standard part of OS/400 Yes Yes Yes Yes No
Type of file Stream Stream Stream Stream Stream
Integrated with OfficeVision (for example, file can be mailed) No No No No No
Access through OS/400 file server Yes Yes Yes Yes Yes
Direct access through the Integrated PC Server (FSIOP) 1 No No No No Yes
Comparative speed for open/close Low Low 2 Medium 2 Medium 2 High 11
Case-sensitive name search No No 2 Yes 12 Varies 2 No
Maximum length of each component in path name Varies 4 Varies 2 255 char Varies 2 255 char 13
Maximum length of path name 294 char No limit 2 16MB No limit 2 255 char
Maximum length of extended attributes for an object 8MB 0 6 2GB 10 0 6 64KB
Maximum levels of directory hierarchy within file system No limit 7 No limit 2 No limit 7 No limit 2 100
Maximum links per object 7 1 1 Varies 15 Varies 2 1
Supports symbolic links No No Yes Yes 2 No
Object/file can have owner No No 9 Yes Yes 2 Yes
Supports integrated file system commands Yes Yes Yes Yes Yes
Supports integrated file system APIs Yes Yes Yes Yes Yes
Supports hierarchical file system (HFS) APIs Yes No No No 2 No
Threadsafe 14 Yes No Yes No No
Supports object journaling No No Yes No No
Notes:
  1. The file server I/O processor is hardware used by LAN Server.
  2. Depends on which remote file system is being accessed.
  3. When accessed through the OS/400 file server
  4. See Optical File System (QOPT) for details.
  5. Assuming an absolute path name that begins with / followed by the file system name.
  6. The QFileSvr.400 file system does not return extended attributes even if the file system being accessed supports extended attributes.
  7. In practice, directory levels are limited by program and system space limits.
  8. Except a directory, which can have only one link to another directory.
  9. The file system being accessed may support object owners.
  10. The maximum length of extended attributes for the UDFS itself cannot exceed 40 bytes.
  11. When accessed through a Novell NetWare client PC. Access using iSeries APIs is comparatively slow.
  12. Case-sensitivity can be specified when a UDFS is created. If the *MIXED parameter is used when creating a UDFS, it will allow a case-sensitive search.
  13. NetWare Directory Services objects are a maximum of 255 characters. Files and directories are limited to DOS 8.3 format.
  14. Integrated file system APIs are threadsafe when they are accessed in a multi-thread capable process. The file system does not allow accesses to the file systems that are not threadsafe.
  15. *TYPE2 directories have a limit of one million links per object. *TYPE1 directories have a limit of 32, 767 links per object. For more information, see *TYPE2 directories.

Abbreviations

char = characters

B = bytes   KB = kilobytes   MB = megabytes   GB = gigabytes

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