--On February 6, 2013 5:21:39 PM -0600 dte...@freebsd.org wrote:



-----Original Message-----
From: owner-freebsd-questi...@freebsd.org [mailto:owner-freebsd-
questi...@freebsd.org] On Behalf Of Paul Schmehl
Sent: Wednesday, February 06, 2013 9:59 AM
To: FreeBSD Questions List
Subject: How to add unused space to an existing install

I have a FreeBSD 8.3 RELEASE box that we recently discovered only has
part of the "disk" being used.  This box has four 1TB drives in RAID 5,
and df only shows 500MB of disk available.

fdisk shows this:
# fdisk -p
# /dev/mfid0
g c364602 h255 s63
p 1 0xa5 63 1562363771
a 1

When I run the fdisk editor in sysinstall I see this:

Disk name:      mfid0                                  FDISK Partition
Editor
DISK Geometry:  364602 cyls/255 heads/63 sectors = 5857331130 sectors
(2860024MB)

Offset       Size(ST)        End     Name  PType       Desc  Subtype
Flags

         0         63         62        -     12     unused        0
        63 1562363771 1562363833  mfid0s1      8    freebsd      165
1562363834 4294981702 5857345535        -     12     unused        0

I want to capture all that unused space and add it to the server.

fstab has this:
# cat /etc/fstab
# Device                Mountpoint      FStype  Options         Dump
        Pass#
/dev/mfid0s1b           none            swap    sw              0       0
/dev/mfid0s1a           /               ufs     rw              1       1
/dev/mfid0s1e           /home           ufs     rw              2       2
/dev/mfid0s1d           /tmp            ufs     rw              2       2
/dev/mfid0s1f           /usr            ufs     rw              2       2
/dev/mfid0s1g           /var            ufs     rw              2       2
/dev/acd0               /cdrom          cd9660  ro,noauto       0       0

When I try to create a new slice using fdisk, it doesn't seem to work.

Did you try something like:

echo "p 2 165 * *" | sudo fdisk -f- /dev/mfid0

??

Thank you for your detailed and informative answer.

I did not. I'm a neophyte in the disk world. I've always used sysinstall to setup partitions and mount points.


Afterward "fdisk -p" should show something like...

# /dev/mfid0
g c364602 h255 s63
p 1 0xa5 63 1562363771
p 2 0xa5 <num> <num>
a 1

And then you'll have /dev/mfid0s2 which you can do-with what you like
(directly newfs the slice or create BSD partitions underneath that to
further sub-divide into as many as 8 smaller units, /dev/mfid0s2[a-h]).


I've been doing some more research on this problem, and I've discovered that bsdlabel has a 2 to the 32nd limit on disk size. It appears I have to use gpart instead. Is that not correct?


If I move to the label editor, I get this:

 FreeBSD Disklabel Editor

Disk: mfid0     Partition name: mfid0s1 Free: 0 blocks (0MB)

Part      Mount          Size Newfs   Part      Mount          Size Newfs
----      -----          ---- -----   ----      -----          ---- -----
mfid0s1a  <none>       2000MB *
mfid0s1d  <none>      65536MB *
mfid0s1e  <none>       4096MB *
mfid0s1b  swap        65536MB SWAP
mfid0s1f  <none>      10240MB *
mfid0s1g  <none>        601GB *

As you can see mfid0s1g is 601GB, and according to fstab that's /var.

Yet df -h shows:

# df -h
Filesystem       Size    Used   Avail Capacity  Mounted on
/dev/mfid0s1a    1.9G    726M    1.0G    41%    /
devfs            1.0k    1.0k      0B   100%    /dev
/dev/mfid0s1e    3.9G     38M    3.5G     1%    /home
/dev/mfid0s1d     62G    6.6M     57G     0%    /tmp
/dev/mfid0s1f    9.7G    7.5G    1.4G    84%    /usr
/dev/mfid0s1g    582G     39G    496G     7%    /var

So apparently I'm not creating this new slice?  It should be
/dev/mfid0s1h, correct?


Let's not confuse slices (DOS partitions) with disklabels (BSD
partitions).

OK. I've clearly done that. As I say, I'm a neophyte in the disk geometry and configuration field.


DOS partitions are (maximum 4 per disk):

mfid0s1
mfid0s2
mfid0s3
mfid0s4

(according to your "fdisk -p" output, you're mfid0 disk is currently only
using mfid0s1)

BSD partitions are (maximum 8 per "slice" aka DOS partition):

mfid0s1a
mfid0s1b
mfid0s1c
mfid0s1d
mfid0s1e
mfid0s1f
mfid0s1g
mfid0s1h

(according to your sysinstall output, you're mfid0s1 slice has 5 BSD
partitions -- a, e, d, f, and g)


I see.


How to I "recapture" the remaining 2+TB of space that's not being used?


The easiest way to use your extra space is to not adjust one of those 5
BSD partitions, but instead create a new DOS partition (mfid0s2 as
previously discussed above). However, if you *really* want to "grow" an
existing BSD partition, this can be done (very carefully).


I'm all for taking the easy way out. :-)


First, you'll want to save the output of "disklabel -r mfid0s1" to a text
file.

Next, you'll have to re-fdisk mfid0 so that the first slice covers the
entire disk. Of course, re-mastering the slices does not affect the data,
but it _will_ wipe out the BSD partition map (the disklabels; in other
words, after using fdisk to adjust the slice size of the first DOS
partition, "disklabel -r mfid0s1" will no longer return what it had
before -- you'll have no disklabels after), so the previous step of
backing up the output of "disklabel -r ..." is paramount.

Next, you'll have to restore the disklabel (using "disklabel -e mfid0s1"
and cross-referencing your backup text file) with one slight adjustment...

You're going to use the *exact* values you backed up _EXCEPT_ you're
going to make the last label (position-wise -- taking care to note the
byte ranges of each disklabel -- ignoring "c" which of course is a pseudo
label for "whole slice") bigger while keeping the same offset (only the
size of the last label should change).

In your case, given the output you provided from sysinstall, this would
likely be your "g" label (but I'd have to see your "disklabel -r" output
to know for sure -- again, taking care to analyze the byte ranges).

Once you've re-written the disklabels (making sure to change nothing from
your previous backup except the size of the last label to cover the new
unused space), you're now at a position where you can "grow" the label
with:

growfs /dev/mfid0s1g

NOTE: Should be done from a LiveFS (read: not while booted from said
filesystem).

That will zero out the unused inodes and make the new space available.
Upon your next boot you'll now have the new storage space available to
your "g" label (/var from the looks of it).

NOTE: If you wanted to change "g" to your "/usr" partition, rsync is your
friend -- while booted from a LiveFS like DruidBSD or mfsBSD etc.).

Excellent information.  Thank you.

--
Paul Schmehl, Senior Infosec Analyst
As if it wasn't already obvious, my opinions
are my own and not those of my employer.
*******************************************
"It is as useless to argue with those who have
renounced the use of reason as to administer
medication to the dead." Thomas Jefferson
"There are some ideas so wrong that only a very
intelligent person could believe in them." George Orwell

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