Supported File and File System Sizes for HFS and JFS Whitepaper

HP-UX 10.01 Compatibility Notes
The following sections are relevant to HP-UX 10.01 versions and not applicable for HP-UX 11i v2 and
11i v3.
Following are the topics covered in this section:
• Large File System Compatibility Issues
• Large Files with Memory Mapping
• Large File System (> 4 TB) File System Block Size Issues
• Related Patches
Large File System (> 2 TB) Compatibility Issues
• The ustat system call returns information about a mounted file system.
• The statfs function returns status information for a mounted file system.
• The statvfs function returns information about a mounted file system.
There is a compatibility issue involving old binaries that still use ustat, the various forms of statfs (fstatfs,
statfsdev, fstatfsdev), and the various forms of the 32-bit flavor of statvfs (fstatvfs, statvfsdev, fstatfsdev).
When these old binaries are exposed to a truly large file system, these calls will return an EOVERFLOW
error that the binaries have never seen before. In some cases, this may be interpreted as a file being
absent (some libraries and commands look at the -1 result, but not the u.uerror) or draw other incorrect
conclusions. HP-provided command and library code has been updated to use the 64-bit flavor of
statvfs, so rebuilt binaries should not have this problem. The bottom line is that administrators need to
be aware of this when setting up their file systems. These older binaries need to be run against data
that resides on smaller file systems, rather than new, huge ones that will overflow the various 32-bit
status fields.
Large Files with Memory Mapping
Use of large files in conjunction with memory mapping (via the mmap system call) requires large
amounts of swap space to be configured in the system to make it perform. For example, if a 1 TB file is
memory mapped by an application, the system should have between 8 to16 GB of swap space.
Large File System (> 4 TB) File System Block Size Issues
Large file systems (> 4 TB) require certain block size requirements. For example, in order to create a file
system that is larger than 16 TB, a file system block size of 8 KB is necessary. You can obtain more
information on the file system block size requirements through the mkfs_vxfs(1m) manpage.
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