SUMMARY: ufsdump question

From: Todd Urie <>
Date: Mon Mar 18 2002 - 11:18:22 EST
First of all, thanks to all that responded to my question.  The information
was very helpful.  In some cases, it reminded of things that I should have
remembered myself (e.g. tar isn't going to do a 'perfect' backup of an
active file system either).  The following people provided the responses
found below:

Tim Chapman
Gustavo Lozano
Andrew Rotramel
Steve Hunt
Callum Hughes
Jeff Horwitz
Hans Schaechl
Yura Pismerov
Steve Elliot
Joe Fletcher
John Jullian
Peter Duncan
Kevin Metzger
Bara Zani

* Tim Chipman

ufsdump 'prefers' if you unmount the filesystem, or at least if it is

However, everyone I've spoken to on the topic basically suggests,

-> Only "active files" will have any problems (if you fail to unmount or
backup a "live" filesystem..)

-> assuming you are dumping system slices, and NOT installing softare at the
same time, this typically amounts to log files having some content

-> If you are doing "disaster recovery" dumps then ... you really don't care
a few logfiles are missing a couple of lines, if the backup is enough to get
your system up and running!

-> For existing free backup options, check: - maybe
something of use is there for you?

Hope this helps a bit,

Tim Chipman

* Gustavo Lozano
Hello Todd

Curently we do perform backups for large systems without umount anything.

It worked fine for us the only thing that can happen is that the files
which are open when you are performing the backup are not included.

If you find this ok or you have another answer please submit the SUMMARY


* Andrew Rotramel
We clone our boot disks using ufsdump and don't unmount them first. ufsdump
seems to work fine even though the source is mounted.


* Steve Hunt

the unmounting of filesystems is a total ideal world thing - i don't
think anyone
 who uses ufsdump does this - ufsdump merely suffers from all the same
 that all other backups face on live filesystems (ie. files growing,
changing and being
 created or deleted during the duration of the backup) - it's just that
 works at a lower level and designed to create far larger archives.
Anyway, we use it here over night and have no problems with it (do some
 with tar and have more problems with them) - just pick a time when the
 is going to be fairly quiet and you'll be fine.
If there is no time when the filesystem is quiet you should consider
looking at the
 fs-snap thing in Solaris 8 (all the technical terms here ;) or using
ODS mirrors
 (splitting the mirror, attaching the unused half somewhere read only,
backing this
 up, reattaching the mirror) - beyond that you'll have to start spending
more dosh!
Hope that helps!

* Callum Hughes

We use ufsdump on a number of servers, both live and development and have
unmounted the filesystems. I seem to remember asking Sun about this and they
said that it was more of a guideline than a rule. We've not had any problems
resulting from this and have restored data from the media in question.

If you're using Solaris 8 then you can use ufsdump in conjunction with
I think... apparently... which will actually allow you to unmount a snapshot
the filesystem... apparently... I say this because I don't have Solaris 8
actually running!

Hope this helps...


* Jeff Horwitz
if a file system is mostly inactive during the backup, you won't have a
using ufsdump on a mounted file system.  just don't run it on a file system
with an active database!

however, if you're using solaris 8,
you can take advantage of the UFS snapshot feature -- you take a snapshot of
the file system which takes up very little space and back up the snapshot.
there are some minor quirks here and there but it works pretty well.  man
fssnap for more info.  this feature may also be available in a later patch
release of solaris 7, but i'm not sure.


* Hans Schaechl

Some people just don't care about what man-pages
say ;) So, if you really want to make sure you
have a consistent filesystem backup either unmount
or use a snapshot facility like Instant Image or
fssnap which comes with Solaris 8 01/01 and later.

Solaris 8 System Administration Supplement


* Yura Pismerov
Todd Urie wrote:
> I have been setting up some backup scripts for a company and have
> contemplated using 'ufsdump'.  However, the systems involved are
> systems and unmounting file systems is out of the question.  Therefore, I
> had ruled out 'ufsdump' because the documentation says that it requires
> systems to be unmounted.

Untrue. It only requires relatively "calm" filesystem during the
It can fail if the FS is very active.

* Steve Elliot
I think it's a case of weighing up the pros and the cons.
If you don't umount a fs before doing a dump, any open file will not
be backed up.
But, what are the chances that that open file will be accidentally deleted
by the user?
I've used only ufsdump since I started sys admin 10 years ago and never
bothered with umounts. Never had a problem restoring.

Steve Elliott

* Joe Fletcher
You don't have to unmount a filesystem to use ufsdump.

* John Jullian
both ufsdump and tar will have problems with files that change as they are
read. Most cases, this is not important with log files but very important
with db files.

John Julian

* Peter Duncan

I have been using UFSDUMP on live sytems for a few years now.  The systems
do not need to unmount anything, it all works perfectly well as is.  I have
done many ufsrestores also and have had no problems

Peter Duncan

* Kevin Metzger
We use ufsdump and we do not unmount the file systems.  I have a 12 hour
window to do bakups where there is little or no user activity, though.  I
don't remember, but I think ufsdump will skip open files.  Tested many times
and proven reliable.

Kevin Metzger

* Bara Zani
I used ufsdump succssefully on over 100 machines without umounting any of
more important I have restored full systems from these backups with no
problem ;-)

Todd Urie
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Received on Mon Mar 18 10:19:18 2002

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