Date: Mon, 22 Sep 2008 17:11:31 -0500 (CDT)
From: Scott Bennett <bennett@cs.niu.edu>
To: freebsd-questions@freebsd.org
Cc: Jerry McAllister <jerrymc@msu.edu>
Subject: Re: looking for a disk partition ("slice") editor
Message-ID: <200809222211.m8MMBVVO018503@mp.cs.niu.edu>
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On Mon, 22 Sep 2008 11:28:05 -0400 Jerry McAllister <jerrymc@msu.edu>
wrote:
>On Sun, Sep 21, 2008 at 09:19:40AM -0500, Scott Bennett wrote:
>
>> On Sun, 21 Sep 2008 09:25:19 -0400 Jerry McAllister <jerrymc@msu.edu>
>> wrote:
>> >On Sun, Sep 21, 2008 at 07:00:39AM -0500, Scott Bennett wrote:
>> >
>> >> I would like to find a disk partition ("slice" in FreeBSD nomenclature)
>> >> editor that runs under FreeBSD that is able to deal properly with logical
>> >> partition entries chained from an extended partition entry in the Master Boot
>> >> Record. fdisk(8) appears to be too primitive to understand logical partitions.
>> >
>> >I am not clear about what you are trying to do, but fdisk should not
>> >be mucking with so-called logical partitions. FreeBSD does not
>>
>> As I wrote already, I do know that fdisk(8) does not understand
>> logical partitions, so forget fdisk. I'm looking for something that
>> does understand them.
>>
>> >really deal with 'logical' partitions'. Anyway, they are more akin
>>
>> It certainly does. I've been using them since I first installed
>> FreeBSD 5.2.1 in 2005, and FreeBSD understands them just fine. The
>> FreeBSD boot loader is another matter, but it's probably not big enough
>> to be that smart.
>>
>> >to FreeBSD partitions than slices. Slices are the primary division
>>
>> No, they are not. They exist because the design for the Master Boot
>> Record only has four entries, which originally limited one to having no
>> more than four disk partitions.
>
>Yes, of course, there is some reason there are four and that reason is
>almost always because a table somewhere has been allocated with only
>room for those.
>
>Yes, all divisions that are made on a disk are logical - even sectors
>and cylyndars in some sense.
>
"Logical partition" is standard terminology, as are "primary partition",
"extended partition", and "Master Boot Record". I am surprised that you are
unfamiliar with these. In any case, I defined logical and extended partitions
for you.
>And below, yup, just what we all said. The slices are subdivided in
>to other logical divisions. Yes, FreeBSD can talk to MS type logical
>divisions.
Perhaps you could provide your definition of a "MS type logical
division", a term I don't know and haven't used. But it isn't relevant
here anyway, so it doesn't matter much whether you do or don't.
>
>But, they don't exactly mix. A MS logical partition doesn't fit
>in a FreeBSD slice being used as a FreeBSD slice.
>
I'm not sure what you mean by "a MS logical partition", but trying to
fit a logical partition into anything but the extended partition is
meaningless. However, using a logical partition as a FreeBSD slice is
perfectly normal. The only catch is that the FreeBSD boot loader has to
boot from a FreeBSD root file system located inside a FreeBSD slice that is
a primary partition. I confess that I don't know whether using some other
boot loader (e.g., grub) would allow one to boot from a FreeBSD root file
system in a slice that is a logical partition because I haven't tried it,
but I have been told by others that it does indeed work.
Here are the device nodes for the drive that I need to repartition:
crw-r----- 1 root operator 0, 149 Aug 28 15:48 /dev/da2
crw-r----- 1 root operator 0, 150 Aug 28 15:48 /dev/da2s1
crw-r----- 1 root operator 0, 151 Aug 28 15:48 /dev/da2s2
crw-r----- 1 root operator 0, 152 Aug 28 15:48 /dev/da2s3
crw-r----- 1 root operator 0, 153 Aug 28 15:48 /dev/da2s4
crw-r----- 1 root operator 0, 159 Aug 28 15:48 /dev/da2s4a
crw-r----- 1 root operator 0, 160 Aug 28 15:48 /dev/da2s4b
crw-r----- 1 root operator 0, 161 Aug 28 15:48 /dev/da2s4c
crw-r----- 1 root operator 0, 162 Aug 28 15:48 /dev/da2s4d
crw-r----- 1 root operator 0, 163 Aug 28 15:48 /dev/da2s4e
crw-r----- 1 root operator 0, 155 Aug 28 15:48 /dev/da2s5
crw-r----- 1 root operator 0, 156 Aug 28 15:48 /dev/da2s6
crw-r----- 1 root operator 0, 164 Aug 28 15:48 /dev/da2s6c
crw-r----- 1 root operator 0, 165 Aug 28 15:48 /dev/da2s6d
crw-r----- 1 root operator 0, 166 Aug 28 15:48 /dev/da2s6e
crw-r----- 1 root operator 0, 200 Aug 28 15:48 /dev/da2s6f
crw-r----- 1 root operator 0, 157 Aug 28 15:48 /dev/da2s7
crw-r----- 1 root operator 0, 158 Aug 28 15:48 /dev/da2s8
crw-r----- 1 root operator 0, 202 Aug 28 15:48 /dev/da2s8c
crw-r----- 1 root operator 0, 203 Aug 28 15:48 /dev/da2s8d
Note that the FreeBSD slices at /dev/da2s[68] do not conform to your
notions. (I see also that I remembered incorrectly the number of
partitions on the disk, but there are enough there to demonstrate
that there are several logical partitions, two of which are also
FreeBSD slices containing FreeBSD partitions.)
I don't know why the FreeBSD developers chose to introduce such
confusing terminology (i.e., a different use of "partition" from the
already existing standard, which then forced them to insert another
term into the FreeBSD lexicon ("slice")). Did they get it from HP-UX,
which is a SysVish system? But it can and should be learned by all
FreeBSD system administrators, of course.
Here is the list for another disk that *id* currently being used:
crw-r----- 1 root operator 0, 135 Aug 28 15:48 /dev/da1
crw-r----- 1 root operator 0, 136 Aug 28 15:48 /dev/da1s1
crw-r----- 1 root operator 0, 137 Aug 28 15:48 /dev/da1s2
crw-r----- 1 root operator 0, 139 Aug 28 15:48 /dev/da1s2a
crw-r----- 1 root operator 0, 140 Aug 28 15:48 /dev/da1s2c
crw-r----- 1 root operator 0, 138 Aug 28 15:48 /dev/da1s3
crw-r----- 1 root operator 0, 141 Aug 28 15:48 /dev/da1s5
crw-r----- 1 root operator 0, 142 Aug 28 15:48 /dev/da1s5c
crw-r----- 1 root operator 0, 143 Aug 28 15:48 /dev/da1s5d
crw-r----- 1 root operator 0, 144 Aug 28 15:48 /dev/da1s5g
crw-r----- 1 root operator 0, 147 Aug 28 15:48 /dev/da1s5g.eli
Note that /dev/da1s[25] are a primary partition and a logical partition,
respectively, that are both FreeBSD slices, the latter of which even
contains an encrypted FreeBSD partition (/dev/da1s5g.eli at /dev/da1s5g).
Scott Bennett, Comm. ASMELG, CFIAG
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