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CVMKFILE(1)                                                                                      CVMKFILE(1)



NAME
       cvmkfile - Create a pre-allocated file

SYNOPSIS
       cvmkfile [-epswz] [-k key] size[k|m|g|t] 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 spec-ifying specifying
       ifying the key value, which is used as the affinity locator.  See  snfs_config(5)  for  more  details
       about affinities.

       WARNING: This will destroy all existing data for the specified file unless the -e option is used.

OPTIONS
       -e     The  -e  option  tells  cvmkfile  not  to  clobber an existing file, just expand or verify the
              requested space.  The default behavior is to unlink and re-create an existing file (see  WARN-ING WARNING
              ING above).

       -k key 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.

       -p     The -p option forces the allocation and any subsequent expansions to be fitted "perfectly"  as
              multiples  of  the  PerfectFitSize  configuration parameter. The allocation extent will always
              line up on and be a perfect multiple of the number of blocks specified in PerfectFitSize.

       -s     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.

       -w     The -w option sets the file size to be equal to size. Without this option the blocks are allo-cated allocated
              cated  but the size is set to zero. NOTE: Unless the -z option is used, the new file will con-tain contain
              tain undefined data. Using the -w option is not recommended unless absolutely needed.

       -z     The -z option causes the file to be physically zeroed out. This can take a significant  amount
              of time.

       size[k|m|g|t]
              The  size  argument  specifies  the number of bytes, kilobytes(k), megabytes(m), gigabytes(g),
              terabytes(t) 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.

       filename
              The file to be created.

EXAMPLES
       Make  a  file  of one gigabyte with zero length. Allocate it on a storage pool that has specified the
       affinity key 6100_n8.

          rock # cvmkfile -k 6100_n8 1g foobar

SEE ALSO
       snfs_config(5), cvmkdir(1)



Xsan File System                                December 2005                                    CVMKFILE(1)