Tru64 Managers:
The recommendations were to use 'tar' or 'cpio'
'cpio' was favored because it can handle a large list of file names.
'tar' was favored because it is very portable
'pax' is a newer open standard (seems to be available on at least Tru64 and
HP-UX)
Notes:
Cpio : use 'portable' format (option c or -H crc)
Use larger block sizes
Tar restore requires reading in the entire archive
ACLs would not be captured on any kind of 'portable' tape
Recommendations against 'dump' and 'vdump'
My next step will be to research the 'pax' command.
Thanks again for the assistance and many replies.
Robert
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tar or cpio. Pay close attention to the largest file size
that you may have to deal with. Both tar and cpio are
likely to have 8 GB file size limits using their defaults.
Extensions to support archiving larger files may be a bit
vendor specific. As noted in "ALAN'S E-MAIL" (me), the
choice of which may come down to personal preference over
the interface used to create and extract an archive.
On the media side, 5 years is getting to the point where
you'd want to consider transferring the data to current
generation media.
---------------
Exclude "dump" (IMHO, good for complete file systems, but not for
custom-made collections).
I personally prefer "cpio" over "tar", because the former can handle
large lists of file names (via stdin) whereas the latter needed
all names as command arguments (this has changed recently, but I
would prefer not to rely on that, especially cross-platform).
With "cpio", ensure you use a "portable" header format -
in former times, this was the "c" option,
with GNU "cpio", it is "-H crc" AFAIR.
For performance reasons, use large blocks; for portability reasons,
I would stay below 64 kB (assume some 16 bit addressing somewhere
in the chain), so my proposal is 48 kB.
-----------
I normally use cpio with the -c option (-c is for character based headers,
no binary). cpio does not backup special files, but that should not be a
problem in your case.
You might also want to look into PAX, since it is supposed to be the new
backup standard, but I'm not sure it is really all that common. (I have
never used pax, so don't let me lead you one way or another.)
One big, big caution.
ACLs. If you have ACLs (C2 Access Control Lists natively supported in
AdvFS) that you need to maintain, then I think you have zero portable
solutions.
Also, if you use backup options to backup the ACLs, you may have trouble
years from now.
FYI: Compaq has extended tar to support ACLs, but I think you have to give
it an option to kick in this non-standard feature.
-----------
Either tar or cpio, in their POSIX-standard forms (i.e. the ones supported
by the pax utility). Actually, anything for which you have full
documentation will do. (That rules out vdump, I believe.)
See "man pax" for details.
The type of tape drive is pretty much irrelevant, except that you may want
to choose a good block size (larger than tar and cpio's defaults). 63kB is
pretty much canonical.
-----
For portability I'd use tar.
A few years ago in another job, I read a 5 year old Concurrent Computers
CV-UX tar on an IBM AIX System and was surprised to find it worked. Just to
see if I could, I tried it on SUN and was able to read it there as well.
-----
Use vdump if you want to restore it using Tru64.
Otherwise a combination of TAR files combined with cpio to a tape using the
default block size will work. It will be very slow but it should transcend
platforms with ease.
Jeff
-----
If you're going to assume another OS in 5 years, then I'd choose Tar.
(assuming that you'd move these files into a directory before the tar):
cd /path/to/directory_where_the_archives_live
tar -cvf /dev/tapedevice .
The problem with this is: If you have to pull just one file off, you'll end
up extracting the entire tarball first just to get the one file. However,
since a tar made on a Tru64 box is able to be opened on Solaris and other
UNIX's, this minor inconvenience seems manageable.
We've tried making a Legato tape to send to another office that uses Solaris
instead of Tru64 and they couldn't read the tape on their Legato Servers
(though this may have been because of their skills in Legato and not knowing
about the 'scanner' command and not any particular problem with
cross-platform Legato restores). The only tape we could create that they
could read on their Solaris systems was ones created with tar. However, if
you ask Legato, they may be able to tell you a way to read these Tru64 tapes
on other platforms (or tell you that it is not possible).
----
-----Original Message-----
From: Aldridge, Robert E.
Sent: Monday, March 04, 2002 12:09 PM
To: tru64-unix-managers
Subject: Recommendations for archiving files
Tru64 Managers:
On our Tru64 5.1 cluster, we want to archive about 50GB of files for the
users. What's the recommended format for this archive?
For daily backups, we use Legato Networker -- but I'm not sure I want to use
Networker for something I might have to go back to in 5 years.
Assuming I use the DLT40/80 tape drive on the system, what format would you
recommend? Dump? Tar? Cpio?
Specific command examples (and switches) would be appreciated.
I also have to assume that I might have another brand of Unix in 5 years --
so I don't want a vendor-specific format.
I searched the Tru64 mailing archive, and came up with a decent summary of
the same problem. I'm just looking for validation (that the information is
still relevant and accurate)...
----------------------------------------------------------------------------
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SUMMARY: Archiving Files to Tape
----------------------------------------------------------------------------
----
To: tru64-unix-managers_at_xxxxxxxx
Subject: SUMMARY: Archiving Files to Tape
Date: Thu, 01 Feb 2001 13:18:16 -0800 (PST)
----------------------------------------------------------------------------
----
...
What is the best method to archive specific files to
DLT tape?
The (Short) Answer is:
tar or cpio, since vdump doesn't archive specific
files (only filesets and subdirectories).
ALAN'S E-MAIL FOLLOWS:
The manual page from V4.0D suggests that vdump can do
subdirectories, but not individual files. The other
significant limitation of vdump is that it uses an
on-media format that can only be read by vdump. That
doesn't make it very portable.
Tar or cpio should be readable by a large number of
other instances of tar or cpio. Which of those to
use may be as much a matter of personal taste as a
matter of capability.
----------------------------------------------------------------------------
----
Thanks for your assistance.
Robert Aldridge
McDermott Technology
Received on Fri Mar 08 2002 - 01:06:16 NZDT