SUMMARY ufsdump

From: Tom Trainor (
Date: Wed Nov 13 1996 - 07:46:13 CST


Thanks to those who replied...I've summarized the replies...
-------------------------------------------------------------------------------- (Frank Pardo)
Ian MacPhedran <> (Jeff Wasilko)
Stuart Pearlman <>
Dan Pritts <>
Rich Kulawiec <>
Question: Can you ufsdump nfs-mounted file systems from the "exportee" system?

In a nutshell---NO!
...[if] Host-1 owns
the filesystems you want to back up, Host-2 owns the tape drive, and the
filesystems are NFS-mounted from Host-1 onto Host-2. And you want to run
ufsdump on Host-2, backing up Host-1's data onto Host-2's tape drive...
...this can't be done on Host-2, but it can be done on Host-1. The command
would be something like this:

 host1# ufsdump 0f Host-2:/dev/rmt/0 /some/local-Host-1/filesystem

I have a little script that does this, backing up (level zero only) one
host's disks onto a different host's tape drive. Let me know if you want
to see it.
..."can you ufsdump an nfs filesystem?", to which the
answer is "no". Ufsdump is for ufs (i.e. local) filesystems.

You can use ufsdump to dump local ufs filesystems to tapes on remote
hosts. This is treated briefly under the ufsdump man page under the "f"
No. ufsdump needs to read the raw filesystem.
...ufsdump reads the raw disk. This is very efficient but requires that
ufsdump know the structure of a filesystem on the disk (where the
superblock is stored, how to find inodes, how to tell which data
blocks belong to which files). Its very filesystem-implementation-
specific. tar, cpio, gnu tar, and other general archive programs
read the filesytem via the normal system calls: opendir, readdir,
closedir for directories and open, read, close for files. They
do not have to know the implementation details of the filesystem
on the disk. They are less efficient than ufsdump, but they
work on any type filesystem the kernel supports.
..."Can I use ufsdump to dump an NFS-exported filesystem from any machine
*other* than the one that it really lives on?" the answer is no. ufsdump
uses the raw filesystem, and so you've got to give it access to that.


Tom Trainor Email: Mobil Oil Corp. Phone: 703-846-3924 3225 Gallows rd / Rm 2B-308 Fax: 703-846-1460 Fairfax Va. 22037-0001

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