How to add unused space to an existing install
pschmehl_lists at tx.rr.com
Thu Feb 7 15:14:29 UTC 2013
--On February 6, 2013 5:21:39 PM -0600 dteske at freebsd.org wrote:
>> -----Original Message-----
>> From: owner-freebsd-questions at freebsd.org [mailto:owner-freebsd-
>> questions at 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
>> DISK Geometry: 364602 cyls/255 heads/63 sectors = 5857331130 sectors
>> Offset Size(ST) End Name PType Desc Subtype
>> 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
>> /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...
> 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
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):
> (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):
> (according to your sysinstall output, you're mfid0s1 slice has 5 BSD
> partitions -- a, e, d, f, and g)
>> 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
> 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
> growfs /dev/mfid0s1g
> NOTE: Should be done from a LiveFS (read: not while booted from said
> 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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