RAID-10 and Volumes

[J. Epperson]

On Tue, December 30, 2008 17:50, Landreth, Kevin wrote:
> Not to sound too hostile here, but what are you two doing?  You can't
> just create a large raid10 and use it for random partitions.  Try
> building VDs for the applications accessing it and use LVM to bring it
> all together (you can jail LVs to particular VDs (PVs in LVM speak)).
> LVM helps keep the raid in alignment as well (because extends don't span
> the entire disk for a single LV, reducing head contention).
>
> If you just insist on using a single large raid10, then carve out 200M
> for /boot, and put the rest into an LVM, with 8G or so for / and split
> up the data any other way you see fit. Partitions are very 1991.
>
> I'm sorry if this is curt or blunt but I couldn't stand by and watch a
> perfectly good array of disks be bludgeoned to death with partitions and
> poor raid configuration.
>
> If you need help with LVM I would suggest #lvm on freenode (I idle
> there, and can help) or the LVM users mailing list.  There is also a
> great document here: http://tldp.org/HOWTO/LVM-HOWTO/ and for kickstart:
> http://fedoraproject.org/wiki/Anaconda/Kickstart (search for logvol for
> an example)
>

I don't get the point of LVM unless you're using it to aggregate disks,
which the RAID controller is doing for you in a case like this.

I rather like the flexibility that physical partitioning gives me.  I can
image a partition and move it around systems or use it for cloning or
recovery.  LVM rather complicates those scenarios.  It also adds a layer
of complexity and overhead in general, although depending on what you're
up to the trade-offs might be worth it.  I used it a lot in the 90s when
9Gb disks were common and RAID wasn't and I needed to build much larger
volumes for databases.  That's not the case now, and even if I need to
expand a partition, tools like Gparted/Qtparted obviate the old "reformat
and repartition" dilemma cited on the tdlp.org pages you refer to. 
Whether I use LVM or partitioning, I still have to resize the FS in such a
scenario.

But perhaps I'm not up to date on the current state of LVM.  The tdlp
HOWTO has not been updated in two years, and the arguments in favor there
are rather 90-ish themselves.  Are there more recent pages on the benefits
you could point me to?