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Date: Wed, 2 Jul 2014 09:50:03 -0600 (MDT)
From: Warren Block <wblock@wonkity.com>
To: Brandon Allbery <allbery.b@gmail.com>
Subject: Re: Dump an Unmounted Journaled UFS Filesystem
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Cc: Dan Plassche <dplassche@gmail.com>,
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On Wed, 2 Jul 2014, Brandon Allbery wrote:

> On Wed, Jul 2, 2014 at 10:14 AM, Warren Block <wblock@wonkity.com> wrote:
>
>> On Tue, 1 Jul 2014, Dan Plassche wrote:
>>
>>  I understand that using dump is not currently recommended on a mounted
>>> journaled UFS2 filesystem.  I prefer to boot from a separate FreeBSD drive
>>> for cold backups anyway, so I'm wondering if there are any issues with
>>> running dump on an unmounted journaled filesystem?  All the discussions
>>> I've seen seem to focus on disabling journaling completely, which I would
>>> like to avoid.
>>>
>>
>> The snapshot code in sys/ufs/ffs/ffs_snapshot.c still prevents making
>> snapshots on SUJ filesystems.
>>
>>
> What exactly is the point of a snapshot for an *unmounted* ("running dump
> on an unmounted journaled filesystem", from above quoted text) filesystem?

There isn't a reason to snapshot an unmounted filesystem, just trying to 
be complete.