File system comparison

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 i5/OS™	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
Integrated with OfficeVision^® (for example, file can be mailed)	No	No	No	Yes	No
Access through i5/OS 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 ¹⁹	255 char ¹⁹	10.6 char ⁶	8.3 char ⁷	255 char ¹⁹
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	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/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 LAN Server. When accessed through the i5/OS file server. When accessed through a LAN Server client PC. Access using iSeries™ APIs is comparatively slow. 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. Up to 10 characters for the object name and up to 6 characters for the object type. Up to 8 characters for the name and 1 to 3 characters for the file type extension (if any). Assuming an absolute path name that 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. Except a directory, which 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. Depends on the system being accessed. QNTC does not support extended attributes. For certain CCSID values, the maximum length can be less than 255 characters. Abbreviations char = characters T1 = TYPE1 STMF T2 = TYPE2 STMF B = bytes KB = kilobytes MB = megabytes GB = gigabytes TB = terabytes

Table 2. File system summary (Part 2 of 2)
Capability	QOPT	QFileSvr.400	UDFS	NFS	QNetWare
Standard part of i5/OS	Yes	Yes	Yes	Yes	No
Type of file	Stream	Stream	Stream	Stream	Stream
File size limit	4 GB	2 GB - 1	T2 = 1 TB; T1=128 GB	Varies ¹⁶	2 GB
Integrated with OfficeVision (for example, file can be mailed)	No	No	No	No	No
Access through i5/OS file server	Yes	Yes	Yes	Yes	Yes
Direct access through the Integrated PC Server 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 ¹⁷	Varies ²	255 char ^{13, 17}
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	Yes	Yes	Yes	No
Supports object journaling	No	No	Yes	No	No
Notes: The file server I/O processor is hardware used by LAN Server. Depends on which remote file system is being accessed. When accessed through the i5/OS file server. See Optical file system (QOPT) for details. Assuming 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. Except a directory, which can have only one link to another directory. The file system being accessed may support object owners. The maximum length of extended attributes for the UDFS itself cannot exceed 40 bytes. When accessed through a Novell NetWare client PC. Access using iSeries APIs is comparatively slow. 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. NetWare Directory Services objects are a maximum of 255 characters. Files and directories are limited to DOS 8.3 format. 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. TYPE2 directories have a limit of one million links per object. TYPE1 directories have a limit of 32 767 links per object. Depends on the system being accessed. For certain CCSID values, the maximum length can be less than 255 characters. Abbreviations* char = characters T1 = TYPE1 STMF T2 = TYPE2 STMF B = bytes KB = kilobytes MB = megabytes GB = gigabytes TB = terabytes