[linux-lvm] Total free space using added VGs and LVs

[brem belguebli]

Hi Lou,

Who is talking about unmounting root ?

I'm just saying shrinking should be possible online as long as some
conditions are met (FS usage less than X %, reduced fragmentation ...)

Of course, this kind of procedure requiring a max of caution because
of the high risk of data loss, I'm not sure it'll get implemented in
the current tools.



2009/10/24, Lou Arnold <larnolda1 at gmail.com>:
> Hahaha. Brem, you and I think alike. If you can do it let me know. I don't
> think people can think of a way to keep the system on-line and yet dismount
> root so that LVM commands can work on it. If you can make it work, I'll buy
> you a virtual beer.
> Regards,
> Lou.
>
> On Sat, Oct 24, 2009 at 10:04 AM, brem belguebli
> <brem.belguebli at gmail.com>wrote:
>
>> It's non sense arguing that LVM is not intended for root due to the
>> fact that you cannot shrink it  (growing online is operational and
>> works fine).
>>
>> This is the only thing that is not allowed, though technically could
>> it be possible.
>>
>>
>>
>> 2009/10/24, Lou Arnold <larnolda1 at gmail.com>:
>>  > Haha, Yes, it would have been nice for someone to have told me about
>> LVM and
>> > root. It would have saved literally days of time. But my work is
>> > experimental and never with production system. In any case, now I know
>> > better.
>> >
>> > As for the LiveCD suggestion, I did not intend to discount it. I had in
>> fact
>> > tried it several times, but with  some success. It probably just a
>> > matter
>> of
>> > finger problems for the failures. But I truly expected a graceful
>> > dismantling process without the need of shutting down the system.
>> >
>> > This was in fact a good experience. When you have to dig into things to
>> > understand why something works or doesn't work, you are always luckier
>> than
>> > if things go perfectly right from the beginning.
>> >
>> > Thanks to everyone for your help.
>> > Lou.
>> >
>> >
>> >
>> > On Fri, Oct 23, 2009 at 5:06 PM, Brian McCullough <bdmc at bdmcc-us.com>
>> wrote:
>> >
>> >> On Fri, Oct 23, 2009 at 01:41:23PM -0700, Lou Arnold wrote:
>> >> > Ryan, Thanks for your suggestion. I know it works, but I had hoped to
>> >> have a
>> >> > solution that didn't stop the whole system while I fixed it.
>> >> >
>> >> > To Drew:
>> >> > I think you were quite right when you spoke about planning the file
>> >> system.
>> >> > I've come to realize that my question is somewhat naive. One simply
>> >> doesn't
>> >> > do what I wanted to exactly because there is no easy way to dismantle
>> >> > it.
>> >> It
>> >> > would be better to partition off some part of the OS drive and add
>> that
>> >> to a
>> >> > new volume group (or a new logical volume group) and mount that under
>> >> > "/mnt", and then add whatever partitions on new drives to that
>> >> > logical
>> >> > volume. That logical volume could be dismounted and worked on,
>> >> > whereas
>> >> > whatever is under root cannot be worked on easily.
>> >>
>> >>
>> >> Lou,
>> >>
>> >> I'm surprised that you haven't yet been told that one of the first
>> >> rules
>> >> of
>> >> LVM is "don't use it for root!"  Actually, I don't really hold with
>> that,
>> >> but it is MUCH more important to plan what you are doing when you do
>> have
>> >> an
>> >> LVM root partition.  As you have found, you can not manipulate an LVM
>> >> partition while it is mounted. ( I know, there are ways for certain
>> types
>> >> of
>> >> filesystems, but in general, the rule holds. )  That is especially true
>> >> when
>> >> the partition that you want to manipulate is root ( / ).
>> >>
>> >> My general practice is to set up the following list of Logical Volumes
>> >> (
>> >> the minimum which serves for most general purpose machines ): root,
>> swap,
>> >> home, usr, var.  I generally allocate somewhere around 1G for the root
>> >> partition.  The others are sized appropriately for the environment.
>>  That
>> >> usually leaves me a lot of free space on modern drives for "data"
>> >> space.
>> >>
>> >> The recommendation that you should find a LiveCD at this point is
>> probably
>> >> one that you should respect.  Playing with mounted filesystems,
>> >> particularly
>> >> root, can rapidly lead you down a very nasty path.
>> >>
>> >>
>> >> Brian
>> >>
>> >> _______________________________________________
>> >> linux-lvm mailing list
>> >> linux-lvm at redhat.com
>> >> https://www.redhat.com/mailman/listinfo/linux-lvm
>> >> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
>> >>
>> >
>>
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>>
>