Date: Thu, 26 Jul 2001 13:26:28 -0400 (EDT) From: James Howard <howardjp@Glue.umd.edu> To: freebsd-hackers@freebsd.org Subject: Backup file formats: tar, cpio, pax, yadda, yadda, yadda Message-ID: <Pine.GSO.4.21.0107261309400.837-100000@z.glue.umd.edu>
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Both tar and cpio seem to have problems doing backups on my
server. Looking at the pax manpage, we see this:
cpio The extended cpio interchange format specified in the IEEE
Std 1003.2 (``POSIX.2'') standard. 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 format) which may be truncated 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 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.
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 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.
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 1003.2 (``POSIX.2'') standard. The default blocksize
for this format is 10240 bytes. Pathnames stored by this
format must be 250 characters or less in length.
Let's review. All the tar formats will truncate long filenames. All the
cpio formats truncate the inode number. Is there a reasonable backup tool
which does not do goofy things like that?
Jamie
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