[Mageia-dev] time to switch from raw partitions to lvm?

[andre999]

Thierry Vignaud a écrit :
>
> On 21 February 2011 08:51, P. Christeas<p_christ at hol.gr>  wrote:
>>> What do you think about switching from defaulting to installing on raw
>>> partitions to lvm
>>> installing on LVs like fedora does ?
>>
>> I vote against that. (=to be enabled by default)
>>
>> LVM is fine for "enterprise" setups, or better, installations where the
>> (expert) admin will need to resize/move partitions in the future. But, for
>> simple machines/users, the complexity of having LVM is IMHO not worth it.
>>
>> (remember also that on all *nix OSes, you can just add a partition, move some
>> files like /usr/share/doc into it and then mount it on /usr/share/doc, thus
>> freeing /usr of some space. No LVM, no virtualization, no ZFS required)
>
> It's not as easy as LVM (need to use a partitionner).
> Diskdrake and the like will force you to umount the partitions to resize
> which may needs to boot on a rescue CD (eg for resizing / fs)
> It may not be possible ie:

A rescue CD like Sysrescuecd is easy to use and comes with all the tools 
needed.
It would be nice if the rescue option of the eventual release Mageia 
dvds contained the few utilities necessary for this.

> - you already have 4 primary partitions and none of them is an extended one.

A gpt partition table solves this problem.
Standard gpt allows 128 partitions in less space than is typically used 
with an mbr partition table with an extended partition.
As well, there is a backup partition table at the end of the disk, so it 
is inherently more reliable.

> - If you've a small 8Go partition at start of the disk followed by one
> To partition
>    and you want to increase the first one, you're screwed without LVM
>    With LVM, you can just got some free space from anywhere (even another disk)

You can do that with symbolic links if you don't want to resize the 
partitions.  Although I wouldn't partition a disk like that in the first 
place.  (I prefer dividing a disk into a least several partitions.  I 
have 8 on my current system.)

> What's more, one gains many features:
>
> - snapshots (yes snapshots for sql db backups are not for end users) but still
>    usefull for saving the whole system at one fixed time
>
> - you can extend some filesystems from space from other disks
>
> - it's easier to add space where needed when defaults partitions sizing proved
>    to be altered after some usage
>
> - one can live resize (w/o umouting/remounting)
>
> - one can use snapshots in order to rollback dangerous update
>    (eg: for trying initscript ->  systemd switch, ...)
>
> I think it brings many usefull features.
> Those who don't want LVM could still do manual partitionning.

These seem to be mostly enterprise-oriented factors, unless I'm missing 
something.
For now at least, I prefer manual partitionning to be the default.

-- 
André