bin/121684: : dump(8) frequently hangs

Jeremy Chadwick koitsu at
Mon Sep 1 22:36:33 UTC 2008

On Mon, Sep 01, 2008 at 02:38:56PM -0700, Jeremy Chadwick wrote:
> The problem was that UFS2 snapshot generation, over time, becomes
> slower and slower to generate (this is what dump does on UFS2 systems,
> with or without the -L flag), and is a known design issue.

Clarification: dump on UFS2 (without -L flag) will NOT generate a
snapshot, but emits a nasty message telling you to use -L on live
filesystems which are mounted r/w.

I'm wondering if people experiencing this problem are using the -L flag
or not (I'm betting most are).  If you are, try removing it and see if
things improve.  But if I remember correctly, there's also a risk
involved with this: not generating a snapshot on UFS2 means your dump
could actually contain "half-written" files (e.g. when you recover, you
might only have a partial file for something that was being written at
the time of dump).

| Jeremy Chadwick                                jdc at |
| Parodius Networking              |
| UNIX Systems Administrator                  Mountain View, CA, USA |
| Making life hard for others since 1977.              PGP: 4BD6C0CB |

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