HP-UX Reference (11i v2 07/12) - 7 Device (Special) Files, 9 General Information, Index (vol 10)

v
vxfsio(7) vxfsio(7)
The reservation amount is independent of file size since reservation is used to preallocate space for a
file.
The a_flags element is used to indicate the type of reservation required. The choices are:
VX_ALIGN
Align all new extents on an ext_size
boundary relative to the starting block of an alloca-
tion unit. If
VX_CONTIGUOUS
is also set, the single extent allocated during this invoca-
tion is not subject to the alignment restriction.
VX_CHGSIZE
The reservation is to be immediately incorporated into the file. The file’s on-disk inode is
updated with the size and block count information that is increased to include the reserved
space. This operation is restricted to users with appropriate privileges.
VX_CONTIGUOUS
The reservation must be allocated contiguously (as a single extent).
ext_size becomes
the fixed extent size for subsequent allocations, but has no affect on this one. The reserva-
tion fails if the file has gone into indirect extents, unless the amount of space requested is
the same as the indirect extent size. If the contiguous allocation request is done on an
empty file, this does happen.
VX_CHGSIZE The reservation is to be immediately incor-
porated into the file. The file’s on-disk inode is updated with the size and block count infor-
mation that is increased to include the reserved space. This operation is restricted to users
with appropriate privileges.
VX_NOEXTEND
The file may not be extended once the current reservation is exceeded. The reservation
may be increased if necessary by another invocation of the ioctl, but the file is not automati-
cally extended.
VX_NORESERVE
The reservation is to be made as a non-persistent allocation to the file. The on-disk inode is
not updated with the reservation information so that the reservation does not survive a sys-
tem crash. The reservation is associated with the file until the close of the file. The reser-
vation is trimmed to the current file size on close.
VX_TRIM
The reservation for the file is to be trimmed to the current file size upon last close by all
processes that have the file open.
Write permission to a file is required to set extent information, but any process that can open the file
can get the extent information. Extent information only applies to regular files. Only one set of
extent information is kept per file. Only the VX_ALIGN and VX_NOEXTEND allocation flags are per-
sistent attributes of the file. Other allocation flags may have persistent effects, but are not visible as
allocation flags. VX_ALIGN, VX_NOEXTEND , and VX_TRIM are the only flags visible through the
VX_GETEXT ioctl.
The VX_SETEXT ioctl returns a zero if the extent information is successfully set. If the operation
fails, the return value is -1 and the external variable errno is a general DIAGNOSTIC.
VX_THAW
Unblock a file system that has been frozen by a VX_FREEZE operation. The argument arg should
be NULL. The process that is to issue a VX_THAW operation must have the root directory of the file
system open, and must ensure that it does not access the file system after the file system has been
frozen, to ensure that the process itself does not block.
Only privileged users can run this command on the root directory of the file system.
The VX_THAW ioctl returns a zero if the file system is successfully unfrozen. If the operation fails,
the return value is -1 and the external variable errno is a general DIAGNOSTIC or one of the diag-
nostics listed in the DIAGNOSTICS section.
232 Hewlett-Packard Company − 5 − HP-UX 11i Version 2: December 2007 Update