how can I restore the backups packaged with pax.

dmac05 · 01-09-2009, 01:47 AM

Hi all,

I have changed my system Alpha ES40 HP Tru64Unix v5.1 to Sun Solaris V890 v5.10.
In my old system i used to backup and restore a 100 GB single file (an oracle logical backup (export) file ) to DDS4 tape driver (two DDS4 data cartridge) with pax tool as fallows:

Backup: pax –w –p e –v –x xtar –f /dev/tape/tape0c
restore: pax –rv –f /dev/tape/tape0c

These commands are working fine on the HPTru64Unix system to backup and restore from a DDS-4 data cartridge.
Now i need to restore these backups to my new system (Sun OS 10).
We have the same applications running on Sun and these commands are not working.

It fails and gives ‘invalid header and long file name errors”. I think its because there is no –x xtar option in pax command in Solaris

I also installed Linux Ubuntu 8.10 and Mandriva 2009 to my desktop, and tried to restore same backups from tape to disk, I got the same error shown below:

[root@localhost /]# pax -rv -f /dev/st0
/tmp/file100.dat
alldata.exp
pax: Invalid header, starting valid header search

I can backup and restore any file with pax tool(without –x xtar option) in Ubuntu and Mandriva. There is no –x xtar option in pax tool here too.

I used this for backup; pax –wvf /dev/st0 .
and for restore: pax -rvf /dev/st0
It has worked without problems.

Now I am trying to find whether -x xtar option is only Tru64Unix dependent or not. Is there a difference in HPTru64 from unix?
How can I restore backups packaged with xtar option to other unix derivatives especially Sun or Mandriva.

Regards
yakup

jschiwal · 01-09-2009, 05:44 AM

When I read the manpage for pax on my SuSE system, the -x option was mentioned. However you didn't indicate what format argument you used for this option.

Code:

-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 1003.2 (``POSIX.2'')
standard. 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.

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
(including the trailing character, which means that filenames can have a maximum
length of 99 characters). Only regular files, hard links, soft links, and directories
will be archived (other file system types are not supported). For backwards compati-
bility 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. Filenames stored by
this format must be 100 characters or less in length (including the trailing charac-
ter, which means that filenames can have a maximum length of 99 characters). Pathnames
(directorynames + filenames) 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.

Mandriva is rpm based, and the pax package supplies only two files, so if this looks promising, you could download the SuSE package from rpm.pbone.net and install it. There could be a problem if the dependent libraries differ however.

jschiwal · 01-09-2009, 05:45 AM

Sorry, you did indicate "xtar". Do you know any more information about this format? Perhaps try restoring with the -x ustar option.

Could the problem have to due with tape handling (mt) instead?

dmac05 · 01-09-2009, 07:27 AM

The man page of pax in HPTru64unix is:

-----------------
-x format
Specifies the output archive format. The pax command recognizes the
following formats:

cpio
Extended cpio interchange format. The default blocking value for
this format for character special archive files is 5120. Blocking
values from 512 to 32,256 in increments of 512 are supported.

xtar
Extended tar interchange format. The default blocking value for
this format for character special archive files is 10240. Blocking
values from 512 to 32,256 in increments of 512 are supported. This
option lets the user archive long file names and extended UID/GID
values.

ustar
Extended tar interchange format. This is the default output
archive format. The default blocking value for this format for
character special archive files is 10240. Blocking values from 512
to 32,256 in increments of 512 are supported.

Any attempt to append to an archive file in a format different from the
existing archive format causes the pax command to exit immediately with
a nonzero exit status.
--------------------

These commands are working fine in HPTru64.
Backup: pax –w –p e –v –x xtar –f /dev/tape/tape0c
restore: pax –rv –f /dev/tape/tape0c

I use the same tape driver and cartridges, and i can also backup and restore with pax command without –x xtar option in Mandriva and Ubuntu.