reduce partition size. HELP

Коньков Евгений kes-kes at
Tue Jan 3 20:52:47 UTC 2012

Здравствуйте, Polytropon.

Вы писали 31 декабря 2011 г., 18:15:38:

P> On Sat, 31 Dec 2011 08:45:32 -0700 (MST), Warren Block wrote:
>> On Sat, 31 Dec 2011, ??????? ??????? wrote:
>> > ????????????, Robert.
>> >
>> > ?? ?????? 31 ??????? 2011 ?., 5:16:33:
>> >
>> >
>> > RH> =?windows-1251?B?yu7t/Oru4iDF4uPl7ejp?= writes:
>> >
>> >>>  Is there any way to reduce partition size on live system?
>> >
>> > RH>         No.
>> > RH>         Basic steps:
>> > RH>         0) go to single-user; unmount partition
>> > RH>         1) backup affected partition; test backup
>> > RH>         2) delete old partition
>> > RH>         3) create new/smaller partition
>> > RH>         4) restore from backup
>> >
>> > is there a way to goto singe-user through ssh?
>> Single-user and unmounted partitions are desirable but not required. 
>> See dump(8) about the -L option.

P> Of course. And in addition, how about that?


P> For this example, /dev/ad0s1a is the / partition.
P> There are other partitions (such as /var or /home)
P> associated to other device files. Let's also
P> assume /dev/ad0s1e is the /var partition.

P> Onto the /var partition (or /home or any scratch
P> oartition), copy the content from / (primarily
P> because of /sbin, /bin and maybe /etc); maybe
P> use this approach:

P>         # cd /var
P>         # dump -0 -L -a -u -f - /dev/ad0s1a | restore -r -f -

P> Make sure /var does _not_ contain directory
P> names identical to those found on the / partition!
P> As I said, maybe use /scratch. :-)

P> (Oh, and you can of course shorten the dump
P> parameters to -0Lauf and restore's to -rf,
P> but I chose this representation for making
P> implicitely clear why to use _those_ options.)

P> Then umount / and mount /var (I'll keep this
P> for the example) as the new / (which now has
P> all the things / should have):

P>         # umount /var
P>         # umount -f / ; mount -t ufs /dev/ad0s1e /
I have not tryed, but man says that 'root can not be unmounted'... ((

     -f      The file system is forcibly unmounted.  Active special devices
             continue to work, but all other files return errors if further
             accesses are attempted.  The root file system cannot be forcibly

P> Then the device associated to / should be free
P> to be unmounted - a step desirable, but it should
P> be no a "big" problem to operate on the device
P> files associated with a _mounted_ partition.

P> The more I think about it... /var is a really
P> bad choice. Use /scratch, or at least /home.


It will be very nice to have legacy installed mfsbsd in some reserved
space in swap (like for kenel dumps)

and having, except single user mode, another option in boot promt:
mfsbsd mode.
and 'nextboot --mfsbsd' to set remotely that boot option.

also be very very nice to have behaviour which loads mfsbsd in case of
unproper unmount. Now it is promt to enter #/bin/sh path.
Having mfsbsd installed allow remotely complete/correct all failed
operations that cause normal loading.

also AUTO booting mfsbsd in all cases that crash current system:
panic, deadlock os something else, will allow to analise many things
remotely and save, in some cases, many many time =)

С уважением,
 Коньков                          mailto:kes-kes at

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