cvmkfile(1) cvmkfile(1)
NAME
cvmkfile - Create a pre-allocated file
SYNOPSIS
cvmkfile [-k <key>] [-p] [-s] [-w] [-z] <size>[k|m|g] <filename>
DESCRIPTION
cvmkfile can be used to pre-allocate a file on the Xsan volume. This
is useful and preferable when preparing a file for use in a real-time
or streaming environment as the entire file is represented in only one
file system extent. Additionally, a file can be placed onto a specific
storage pool by specifying the <key> value, which is used as the affin-
ity locator. See cvfs_config(4) for more details about affinities.
USAGE
The -k <key> optionally tells the file system where to place the data
file. If an Affinity Key is specified, the file is placed on storage
pools that are specified to support this key. If there is no storage
pool with the key specified, then the file is placed in non-exclusive
data pools. If there are no non-exclusive data pools, then ENOSPC (no
space) is returned.
The -p option forces the allocation and any subsequent expansions to be
fitted "perfectly" as multiples of the InodeExpandMin configuration
parameter. The allocation extent will always line up on and be a per-
fect multiple of the blocks specified in InodeExpandMin.
The -s option forces the allocation to line up on the beginning block
modulus of the storage pool. This can help performance in situations
where the I/O size perfectly spans the width of the storage pool's
disks.
The -w option sets the file size to be equal to <size>. Without this
option the blocks are allocated but the size is set to zero. NOTE:
Unless the -z option is used, the new file will contain undefined data.
Using the -w option is not recommended unless absolutely needed.
The -z option causes the file to be physically zeroed out. This can
take a significant amount of time.
The <size> argument specifies the number of bytes, kilobytes(k),
megabytes(m) or gigabytes(g) to allocate for the file. There is no
guarantee that all requested space will be allocated. If there is
insufficient contiguous available space to satisfy the requested amount
then a "best effort" will be performed. In this case a success value
is returned even though not all of the requested amount is allocated to
the file. Even though the allocation may not be fully satisfied, if
the -w option is specified then the file size will still reflect the
requested <size> value.
EXAMPLES
Make a file of one gigabyte with zero length. Allocate it on a storage
pool that favors the media type 6100_n8.
rock # cvmkfile -k 6100_n8 1g foobar
SEE ALSO
cvfs_config(4), cvmkdir(1)
Xsan File System December 2005 cvmkfile(1)
Mac OS X 10.7 - Generated Thu Aug 11 07:51:19 CDT 2011