[tech] meito (the new fileserver)

David Luyer david at luyer.net
Thu Aug 29 22:20:16 WST 2002


> > > Luyer's favourite: install GNU tar/cpio (already on morwong) and
> > > "tar cf - ... | cpio -im". I still like dump, but I can't actually
> > > see a /sbin/advfsdump or similar installed at the moment... Odd.

Oh, and, dump is horribly non-portable.  Although I don't know
the system types in question, if you're trying to go from one
FS type to another there's little chance (UFS to UFS across
different OS's can work, though, depending on what OS's exactly).

I used to like dump until I found that ext2 dump was unreliable as
anything, rdump was unusably slow due to having too many send:ack:send
etc inside TCP streams, and vdump couldn't handle rdump even if you
were insane enough to want to try.  Too many traps.

cpio is good :)  Oh, and ignore the warnings about truncating inode
numbers it sometimes generates...

btw:

  cd $input; cpio -pm $output

I meant:

  cd $input; find . -print | cpio -pm $output

Also as to which cpio to use: Solaris and GNU cpio both support
nice cpio file formats.  'pax' can also output to all formats.  In
fact the 'pax' manpage has a good coverage of output formats:

     -x format
           Specify the output archive format, with the default format
being ustar.  pax
           currently supports the following formats:

           cpio     The extended cpio interchange format specified in
the IEEE Std
                    1003.1 (``POSIX.1'') standard.  The default
blocksize for this for-
                    mat is 5120 bytes.  Inode and device information
about a file (used
                    for detecting file hard links by this format) which
may be trun-
                    cated by this format is detected by pax and is
repaired.

           bcpio    The old binary cpio format.  The default blocksize
for this format
                    is 5120 bytes.  This format is not very portable and
should not be
                    used when other formats are available.  Inode and
device informa-
                    tion about a file (used for detecting file hard
links by this for-
                    mat) which may be truncated by this format is
detected by pax and
                    is repaired.

           sv4cpio  The System V release 4 cpio.  The default blocksize
for this format
                    is 5120 bytes.  Inode and device information about a
file (used for
                    detecting file hard links by this format) which may
be truncated by
                    this format is detected by pax and is repaired.

           sv4crc   The System V release 4 cpio with file crc checksums.
The default
                    blocksize for this format is 5120 bytes.  Inode and
device informa-
                    tion about a file (used for detecting file hard
links by this for-
                    mat) which may be truncated by this format is
detected by pax and
                    is repaired.

           tar      The old BSD tar format as found in BSD4.3.  The
default blocksize
                    for this format is 10240 bytes.  Pathnames stored by
this format
                    must be 100 characters or less in length.  Only
regular files, hard
                    links, soft links, and directories will be archived
(other file
                    system types are not supported).  For backwards
compatibility with
                    even older tar formats, a -o option can be used when
writing an
                    archive to omit the storage of directories.  This
option takes the
                    form:
                          -o write_opt=nodir

           ustar    The extended tar interchange format specified in the
IEEE Std
                    1003.1 (``POSIX.1'') standard.  The default
blocksize for this for-
                    mat is 10240 bytes.  Pathnames stored by this format
must be 250
                    characters or less in length.

           pax will detect and report any file that it is unable to
store or extract as
           the result of any specific archive format restrictions.  The
individual
           archive formats may impose additional restrictions on use.
Typical archive
           format restrictions include (but are not limited to): file
pathname length,
           file size, link pathname length, and the type of the file.

David.




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