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

[brem belguebli <brem.belguebli@gmail.com>]

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@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@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
>>
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>> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
>>
>