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CVCP(1)                                                                                              CVCP(1)



NAME
       cvcp - Xsan Copy Utility

SYNOPSIS
       cvcp [options] Source Destination

DESCRIPTION
       cvcp  provides a high speed, multi-threaded copy mechanism for copying directories onto and off of an
       Xsan volume. The utility uses IO strategies and multi-threading techniques that exploit the  Xsan  IO
       model.

       cvcp can work in many modes;
       Directory-to-directory copies of regular files.
       Directory copy of regular files to a Vtape virtual sub-directory.
       Single File-to-File copy.

       In  terms  of  functionality  for  regular files, cvcp is much like the tar(1) utility. However, when
       copying a directory to a Vtape virtual directory, cvcp can rename and renumber the source  images  as
       they  are  being  transferred.  The  files  in  the Source directory must have a decipherable numeric
       sequence embedded in their names.

       The cvcp utility was written to provide high performance data movement, therefore,  unlike  utilities
       such as rsync, it does not write data to temporary files or manipulate the target files' modification
       times to allow recovery of partially-copied files when interrupted.  Because of this, cvcp may  leave
       partially-copied  files  if  interrupted  by  signals such as SIGINT, SIGTERM, or SIGHUP.  Partially-copied Partiallycopied
       copied target files will be of the same size as source files; however, the data  will  be  only  par-tially partially
       tially copied into them.

USAGE
       The  Source parameter determines whether to copy a single file  or use a directory scan.  Source must
       be a directory or file name.

       Using cvcp for directory copies is best accomplished by cd'ing to the Source directory and using  the
       dot  (.)  as the Source. This has been shown to improve performance since fewer paths are searched in
       the directory tree scan.

       The Destination parameter determines the target file or directory.

OPTIONS
       -A     If specified, will turn off the pre-allocation feature. This feature looks at the size of  the
              source  file  and  then  makes an ALLOCSPACE call to the file system. This pre-allocation is a
              performance advantage as the file will only contain a single extent. It also  promotes  volume
              space  savings since files that are dynamically expanded do so in a  more coarse manner. Up to
              30% savings in physical disk space can be seen using the pre-allocation  feature.  NOTE:  Non-Xsan NonXsan
              Xsan  file  systems that do not support pre-allocation will turn pre-allocation off when writ-ing. writing.
              ing. The default is to have the pre-allocation feature on.

       -b buffers
              Set the number of IO buffers to buffers. The default is two times the number of  copy  threads
              started(see  the  -t option). Experimenting with other values between 1 and 2 times the number
              of copy threads may yield performance improvements.

       -C     When specified, this option disables the bulk create optimization.  By default, this optimiza-tion optimization
              tion  is used in certain cases to improve performance.  In some circumstances, the use of bulk
              create can cause cvcp to return errors if the destination file system is StorNext and the  FSM
              process  exits ungracefully while a copy is in progress.  The use of the -B option avoids this
              potentiality at the cost of performance.  The effect on performance  will  depend  on  whether
              bulk  create  is  being  disabled  for other reasons as well as the size of the files with the
              impact being more observable when small files are copied.

       -d     Changes directory-to-directory mode to work more like cp -R.   Without  -d,  cvcp  copies  the
              files and sub-directories under Source to the Destination directory.  With -d, cvcp first cre-ates creates
              ates a sub-directory called Source in the Destination directory, then  copies  the  files  and
              sub-directories under Source to that new sub-directory.

       -k buffer_size
              Set the IO buffer size to buffer_size bytes.  The default buffer size is 4MB.

       -l     If set, copy the target of symbolic links rather than copying the link itself.

       -n     If set, do not recurse into any sub-directories.

       -p source_prefix
              If set, only copy files whose beginning file name characters match source_prefix. The matching
              test only checks starting at character one.

       -s     The -s option forces allocations 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.

       -t num_threads
              Set the number of copy threads to num_threads. The default is 4 copy threads.  This option may
              have  a significant impact on speed and resource consumption.  The total copy buffer pool size
              is calculated by multiplying the number of buffers(-b) by the buffer  size(-k).  Experimenting
              with the -t option along with the -b and -k options are encouraged.

       -u     Update  only.  If  set, copies only when the source file is newer than the destination file or
              the destination file does not exist. Note that file access times have a  granularity  of  only
              one  second,  so  it  is  possible for a source file to be copied over a destination file even
              though -u is used. -u cannot be used with tar files.

       -v     Be verbose about the files being copied.

       -x     If set, ignore umask(1) and retain original permissions from the source file.  If  the  super-user, superuser,
              user, set sticky and setuid/gid bits as well.

       -y     If  set  by  the  super-user,  retain  ownership and group information. If the user is not the
              super-user then this option is silently ignored.

       -z     If set, retain original modification times.

EXAMPLES
       Copy directory abc and its sub-directories to  directory  /usr/clips/foo.  This  copy  will  use  the
       default  number  of copy threads and buffers. The total buffer pool size will total 24MB (6 buffers @
       4MB each).

       Retain all permissions and ownerships. Show all files being copied.

          rock% cvcp -vxy abc /usr/clips/foo

       Copy the same directory the same way, but only those files that start with mumblypeg.

          rock# cvcp -vxy -p mumblypeg abc /usr/clips/foo

       Copy a single file def to the directory /usr/clips/foo/

          rock# cvcp def /usr/clips/foo



       Copy a file sequence in the current directory prefixed with secta with  a  range  from  200  to  300.
       Place the files into the Vtape /usr/clips/n8 yuv sub-directory.  Set the target frame to 500. Use the
       verbose option.

          rock% cvcp -v -f 500 -p secta -r 200-300 . /usr/clips/n8/yuv


CVCP TUNING
       cvcp can be tuned to improve performance and resource utilization. By adjusting the  -t,  -k  and  -b
       options cvcp can be optimized for any number of different environments.

       -t num_threads
              Increasing  the  number  of  copy  threads will increase the number of concurrent copies. This
              option is useful when copying large directory structures. Single file copies are not  affected
              by the number of copy threads.

       -b buffers
              The  number  of copy buffer should be set to a number between 1 and 3 times the number of copy
              threads. Increasing the number of copy buffers increases the amount of work that is queued  up
              waiting for an available copy thread, but also increases resource consumption.

       -k buffer_size
              The  size  of  the copy buffer may be tuned to fit the I/O characteristics of a copy. If files
              smaller than 4MB are being copied performance may be improved by reducing  the  size  of  copy
              buffers to more closely match the source file sizes.

       NOTE:  It  is  important  to  ensure  that  the resource consumption of cvcp is tuned to minimize the
       effects of system memory pressure. On systems with limited available physical memory, performance may
       be increased by reducing the resource consumption of cvcp.

SEE ALSO
       cvfs(1)




Xsan File System                                 March 2008                                          CVCP(1)