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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 strate-
       gies 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 imbedded 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 target files will
       be  of  the  same  size as source files; however, the data will be only
       partially 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 file systems that do not sup-
              port pre-allocation will turn pre-allocation off  when  writing.
              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.

       -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 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     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 or with -z.

       -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, set sticky and setuid/gid bits
              as well.

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

       -z     If set, retain original modification times. Cannot be used  with
              -u.


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  num-
       ber of different environments.


       -t     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     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     The size of the copy buffer may be tuned to fit the I/O  charac-
              teristics  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)

Mac OS X 10.7 - Generated Thu Aug 11 07:47:23 CDT 2011
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