UFS Crash and directories now missing

[Alejandro Imass]

On Wed, May 9, 2012 at 9:48 AM, Polytropon <freebsd at edvax.de> wrote:
> On Wed, 9 May 2012 09:30:37 -0400, Alejandro Imass wrote:
>> On Wed, May 9, 2012 at 8:53 AM, Erich Dollansky
>> <erich at alogreentechnologies.com> wrote:
>> >> For your recommendation above, what are the advantages or differences
>> >> of slicing the disk versus partitioning on a single slice?
>> >>
>> > it could be a misunderstanding. What is a partition? What is a slice. I have to look always into the handbook. Anyway, as long the OS see different units which have to be mounted independent of each other, it all does not matter what is what.
>> >
>>
>> I meant in Unix terms of course. Slice is slice (partition in other
>> OS) and partition a thru h
>>
>> The question is if it has any advantage of using a slice to mount the
>> basejail in RO as opposed to doing the same thing on a partition.
>
> The answer is: It it not possible. :-)
>
> You cannot mount a slice.
>
> Given the BSD terminology: A slice _has_ to contain partitions.
> You cannot format a slice, you can only format partitions. A
> formatted partition carries a UFS file system. (However, it's
> possible to omit the slice, and partition the whole disk instead,
> this is called "dedicated mode"). A third method is formatting
> the whole disk ("the 'c' device"), in that case the 'c' is omitted.
>
> The _only_ time you can mount a slice is when it is used in its
> common meaning, being a "DOS primary partition"; in this case,
> a FAT or NTFS file system will be placed directly into a slice,
> as those do not support any (BSD-style) partitioning.
>
> /dev/ad0        -> the disk
> /dev/ad0s1      -> 1st slice
> /dev/ad0s1a     -> 1st partition on 1st slice
>                   THIS is something you can mount.
> -or-
> /dev/ad0a       -> 1st partition on disk ("dedicated")
>                   THIS can also be mounted.
> -or-
> /dev/ad0        -> the whole disk (equals /dev/ad0c)
>                   Even THIS can be mounted.
>
> In case I'm misunderstanding your question, could you alter the
> expression?
>

Thanks. The question was more advantages of a single slice + single
partition versus a slice and multiple partitions, for mounting the
EzJail basejail in RO mode.