04-05-2011
Quote:
Originally Posted by
Mr.AIX
But the number of the files is very huge .. Are you sure this is will success ?
Yes, this will work, regardless of the number of files.
You could use "dd" too, but i would prefer to use an "high-level" approach when possible instead of a "low-level" approach such as "dd". With "dd" it is easily possible to overwrite not only files, but devices, volume group information, things quite vital to your system.
With "tar" you deal with files, directories and the like - things which are easily recognized by you. With "dd" you ultimately deal with devices, which is much more dangerous. If you mistype "/tgtpaath" in the above mentioned "tar" command you will run into a "disk full"-error, have the chance to correct it and start over. If you confuse hdisk127 and hdisk126 in a dd command it will work well but probably destroy data you didn't want to lose.
That doesn't mean at all that "dd" is a bad tool - it is very powerful, but the power comes at the price of being dangerous too. Use it when you need it, not when it is possible, is my principle. Maybe i'm feeble, but i have been working as a Sysadmin for a long time and i am still alive. ;-))
I hope this helps.
bakunin
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LEARN ABOUT CENTOS
virt-tar
virt-tar(1) Virtualization Support virt-tar(1)
NAME
virt-tar - Extract or upload files to a virtual machine
SYNOPSIS
virt-tar [--options] -x domname directory tarball
virt-tar [--options] -u domname tarball directory
virt-tar [--options] disk.img [disk.img ...] -x directory tarball
virt-tar [--options] disk.img [disk.img ...] -u tarball directory
OBSOLETE
This tool is obsolete. Use virt-copy-in(1), virt-copy-out(1), virt-tar-in(1), virt-tar-out(1) as replacements.
EXAMPLES
Download "/home" from the VM into a local tarball:
virt-tar -x domname /home home.tar
virt-tar -zx domname /home home.tar.gz
Upload a local tarball and unpack it inside "/tmp" in the VM:
virt-tar -u domname uploadstuff.tar /tmp
virt-tar -zu domname uploadstuff.tar.gz /tmp
WARNING
You must not use "virt-tar" with the -u option (upload) on live virtual machines. If you do this, you risk disk corruption in the VM.
"virt-tar" tries to stop you from doing this, but doesn't catch all cases.
You can use -x (extract) on live virtual machines, but you might get inconsistent results or errors if there is filesystem activity inside
the VM. If the live VM is synched and quiescent, then "virt-tar" will usually work, but the only way to guarantee consistent results is if
the virtual machine is shut down.
DESCRIPTION
"virt-tar" is a general purpose archive tool for downloading and uploading parts of a guest filesystem. There are many possibilities:
making backups, uploading data files, snooping on guest activity, fixing or customizing guests, etc.
If you want to just view a single file, use virt-cat(1). If you just want to edit a single file, use virt-edit(1). For more complex cases
you should look at the guestfish(1) tool.
There are two modes of operation: -x (eXtract) downloads a directory and its contents (recursively) from the virtual machine into a local
tarball. -u uploads from a local tarball, unpacking it into a directory inside the virtual machine. You cannot use these two options
together.
In addition, you may need to use the -z (gZip) option to enable compression. When uploading, you have to specify -z if the upload file is
compressed because virt-tar won't detect this on its own.
"virt-tar" can only handle tar (optionally gzipped) format tarballs. For example it cannot do PKZip files or bzip2 compression. If you
want that then you'll have to rebuild the tarballs yourself. (This is a limitation of the libguestfs(3) API).
OPTIONS
--help
Display brief help.
--version
Display version number and exit.
-c URI
--connect URI
If using libvirt, connect to the given URI. If omitted, then we connect to the default libvirt hypervisor.
If you specify guest block devices directly, then libvirt is not used at all.
--format raw
Specify the format of disk images given on the command line. If this is omitted then the format is autodetected from the content of
the disk image.
If disk images are requested from libvirt, then this program asks libvirt for this information. In this case, the value of the format
parameter is ignored.
If working with untrusted raw-format guest disk images, you should ensure the format is always specified.
-x
--extract
--download
-u
--upload
Use -x to extract (download) a directory from a virtual machine to a local tarball.
Use -u to upload and unpack from a local tarball into a virtual machine. Please read the "WARNING" section above before using this
option.
You must specify exactly one of these options.
-z
--gzip
Specify that the input or output tarball is gzip-compressed.
SHELL QUOTING
Libvirt guest names can contain arbitrary characters, some of which have meaning to the shell such as "#" and space. You may need to quote
or escape these characters on the command line. See the shell manual page sh(1) for details.
SEE ALSO
guestfs(3), guestfish(1), virt-cat(1), virt-edit(1), virt-copy-in(1), virt-copy-out(1), virt-tar-in(1), virt-tar-out(1), Sys::Guestfs(3),
Sys::Guestfs::Lib(3), Sys::Virt(3), <http://libguestfs.org/>.
AUTHOR
Richard W.M. Jones <http://people.redhat.com/~rjones/>
COPYRIGHT
Copyright (C) 2009 Red Hat Inc.
This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation,
Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
libguestfs-1.18.1 2013-12-07 virt-tar(1)