These tables summarize the features and limitations of
each file system.
Table 1. File
system summary (Part 1 of 2)
Capability |
"root" (/) |
QOpenSys |
QSYS.LIB16 |
QDLS |
QNTC |
Standard part of IBM i |
Yes |
Yes |
Yes |
Yes |
Yes |
Type of file |
Stream |
Stream |
Record 12 |
Stream |
Stream |
File size limit |
T2=1 TB; T1=128 GB |
T2=1 TB; T1=128 GB |
Database file sizes |
4 GB |
Varies 17 |
Access through IBM i 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 characters 3 |
255 characters 3 |
10/6 characters 6 |
8/3 characters 7 |
255 characters 3 |
Maximum length of path name 8 |
16MB |
16MB |
55 – 66 characters4 |
82 characters |
255 characters |
Maximum length of extended attributes
for an object |
2GB |
2GB |
Varies 9 |
32KB |
0 18 |
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 or 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:
- The file server I/O processor is
hardware used by the LAN Server.
- The speed applies when the file system is accessed
through the IBM i file
server.
- For certain CCSID values, the maximum length can
be less than 255 characters.
- The QSYS.LIB file system has a maximum path name length of 55
characters.
The independent ASP QSYS.LIB file system has a maximum path length
of 66 characters.
- See Document library services file system (QDLS) for details.
- This value can be up to 10 characters for the object
name and up to 6 characters for the object type.
- This value can be up to 8 characters for the name
and 1 to 3 characters for the file type extension (if any).
- The values are based on the assumption that an
absolute path name begins with / followed by the file system name
(such as
/QDLS... ).
- 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.
- In practice, directory levels are limited by program and system
space limits.
- An exception to this is a directory that can have
only one link to another directory.
- The user spaces in QSYS.LIB and independent ASP QSYS.LIB file
systems support stream file input and output.
- 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.
- QSYS.LIB and independent ASP QSYS.LIB file systems support journaling
different object types than the "root" (/), UDFS, and QOpenSys file
systems.
- *TYPE2 directories have a limit of one million links per object
and a limit of 999 998 subdirectories. *TYPE1 directories have a limit
of 32 767 links per object.
- Data in this column refers to both the QSYS.LIB file system and
the independent ASP QSYS.LIB file system.
- This limit depends on the system being accessed.
- QNTC does not support extended attributes.
Abbreviations
- T1 = *TYPE1 *STMF
- T2 = *TYPE2 *STMF
- B = bytes KB = kilobytes MB = megabytes
GB = gigabytes TB = terabytes
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Table 2. File system summary (Part 2 of 2)
Capability |
QOPT |
QFileSvr.400 |
UDFS |
NFS |
Standard part of IBM i |
Yes |
Yes |
Yes |
Yes |
Type of file |
Stream |
Stream |
Stream |
Stream |
File size limit |
Varies16 |
Varies 3 |
T2 = 1 TB; T1=128 GB |
Varies 14 |
Access through IBM i file server |
Yes |
Yes |
Yes |
Yes |
Direct access through the file server I/O processor 1 |
No |
No |
No |
No |
Comparative speed for open/close |
Low |
Low 2 |
Medium 2 |
Medium 2 |
Case-sensitive name search |
No |
No 2 |
Yes 11 |
Varies 2 |
Maximum length of each component
in path name |
Varies 4 |
Varies 2 |
255 characters 15 |
Varies 2 |
Maximum length of path name 5 |
294 characters |
No limit 2 |
16 MB |
No limit 2 |
Maximum length of extended attributes
for an object |
8 MB |
0 6 |
2 GB 10 |
0 6 |
Maximum levels of directory hierarchy
within file system |
No limit 7 |
No limit 2 |
No limit 7 |
No limit 2 |
Maximum links per object 8 |
1 |
1 |
Varies 13 |
Varies 2 |
Supports symbolic links |
No |
No |
Yes |
Yes 2 |
Object or file can have owner |
No |
No 9 |
Yes |
Yes 2 |
Supports integrated file system commands |
Yes |
Yes |
Yes |
Yes |
Supports integrated file system APIs |
Yes |
Yes |
Yes |
Yes |
Supports hierarchical file system
(HFS) APIs |
Yes |
No |
No |
No 2 |
Threadsafe 12 |
Yes |
Yes |
Yes |
Yes |
Supports object journaling |
No |
No |
Yes |
No |
Notes:
- The file server I/O processor is
hardware used by the LAN Server.
- This value depends on which remote file system
is being accessed.
- When connected to a system earlier than V6R1,
the file size limit is 2 GB-1. Otherwise, the file size limit depends
on the file system being accessed.
- See Optical file system (QOPT) for details.
- The values are based on the assumption that an
absolute path name that begins with / followed by the file system
name.
- The QFileSvr.400 file system does not return extended attributes
even if the file system being accessed supports extended attributes.
- In practice, directory levels are limited by program and system
space limits.
- An exception to this is a directory that can have
only one link to another directory.
- The file system being accessed might support object owners.
- The maximum length of extended attributes for the UDFS itself
cannot exceed 40 bytes.
- 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.
- Integrated file system APIs are threadsafe when they are accessed
in a multithread capable process. The file system does not allow accesses
to the file systems that are not threadsafe.
- *TYPE2 directories have a limit of one million links per object.
*TYPE1 directories have a limit of 32 767 links per object.
- This limit depends on the system being accessed.
- For certain CCSID values, the maximum length can be less than
255 characters.
- 9,999,999,827,968 bytes when accessing through integrated file
system. 4,294,705,152 bytes when accessing through hierarchical file
system (HFS).
Abbreviations
- T1 = *TYPE1 *STMF
- T2 = *TYPE2 *STMF
- B = bytes KB = kilobytes MB = megabytes
GB = gigabytes TB = terabytes
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