CentOS - Jun 2015 - LVM hatred, was Re: /boot on a separate partition?

On Tue, 23 Jun 2015 10:42:35 -0400
m.roth at 5-cent.us wrote:
> Timothy Murphy wrote:
> > Do most people today have /boot on a separate partition,
> > or do they (you) have it on the / partition ?
> >
> Separate partition, 100% of the time.
Inside / (which is mostly always ext4), 100% of the time. :-)

That said, I prefer virtual machines over multiboot environments, and I
absolutely despise LVM --- that cursed thing is never getting on my
drives. Never again, that is...

HTH, :-)
Marko

On 6/23/2015 10:33 AM, Marko Vojinovic wrote:
> Inside / (which is mostly always ext4), 100% of the time. :-)
>
> That said, I prefer virtual machines over multiboot environments, and I
> absolutely despise LVM --- that cursed thing is never getting on my
> drives. Never again, that is...
I'm curious what has made some people hate LVM so much.  I have been 
using it for years on thousands of production systems with no issues 
that could not be easily explained as myself or someone else doing 
something stupid.  And even those issues were pretty few and far between.

/opens can of worms
> HTH, :-)
> Marko
>
> _______________________________________________
> CentOS mailing list
> CentOS at centos.org
> http://lists.centos.org/mailman/listinfo/centos

On Tue, Jun 23, 2015 at 12:15 PM, Jason Warr <jason at warr.net> wrote:
>
>
> On 6/23/2015 10:33 AM, Marko Vojinovic wrote:
>
>> Inside / (which is mostly always ext4), 100% of the time. :-)
>>
>> That said, I prefer virtual machines over multiboot environments, and I
>> absolutely despise LVM --- that cursed thing is never getting on my
>> drives. Never again, that is...
>>
>
> I'm curious what has made some people hate LVM so much.  I have been
using
> it for years on thousands of

No clue.

My experiences with LVM have been positive as well.
And in opinion it doesn't add much complexity (if you know the LVM tools,
you're fine). Flexibility is worth an ounce of complexity.

> production systems with no issues that could not be easily explained as
> myself or someone else doing something stupid.  And even those issues were
> pretty few and far between.
>
The worst "nail biter" I had was an instance where a former employee
did
not properly allocate LV space to /var and I had to reclaim space from
rootfs and add it to /var.  Even a small screw up and I'd have to go
recover from my backups (not fun).  Fortunately I spun up VMs and labbed
everything a few times over and wrote detailed notes. Went without a hitch.

Prior Proper Planning Prevents Poor Performance

>
> /opens can of worms
>
I'll bite, see above ;-)

>
>  HTH, :-)
>> Marko
>>
>> _______________________________________________
>> CentOS mailing list
>> CentOS at centos.org
>> http://lists.centos.org/mailman/listinfo/centos
>>
>
> _______________________________________________
> CentOS mailing list
> CentOS at centos.org
> http://lists.centos.org/mailman/listinfo/centos
>


-- 
---~~.~~---
Mike
//  SilverTip257  //

On Tue, 23 Jun 2015 11:15:30 -0500
Jason Warr <jason at warr.net> wrote:
> 
> I'm curious what has made some people hate LVM so much.  I have been 
> using it for years on thousands of production systems with no issues 
> that could not be easily explained as myself or someone else doing 
> something stupid.  And even those issues were pretty few and far
> between.
> 
> /opens can of worms
Well, I can only tell you my own story, I wouldn't know about other
people. Basically, it boils down to the following:

(1) I have no valid usecase for it. I don't remember when was the last
time I needed to resize partitions (probably back when I was trying to
install Windows 95). Disk space is very cheap, and if I really need to
have *that* much data on a single partition, another drive and a few
intelligently placed symlinks are usually enough. Cases where a symlink
cannot do the job are indicative of a bad data structure design, and
LVM is often not a solution, but a patch over a deeper problem
elsewhere. Though I do admit there are some valid usecases for LVM.

(2) It is fragile. If you have data on top of LVM spread over an array
of disks, and one disk dies, the data on the whole array goes away. I
don't know why such a design of LVM was preferred over something more
robust (I guess there are reasons), but it doesn't feel right. A bunch
of flawless drives containing corrupt data is Just Wrong(tm). I know,
one should always have backups, but still...

(3) It's being pushed as default on everyday ordinary users, who have
absolutely no need for it. I would understand it as an opt-in feature
that some people might need in datacenters, drive farms, clouds, etc.,
but an ordinary user installing a single OS on their everyday laptop
just doesn't need it. Jumping through hoops during installation to
opt-in LVM by a small number of experts outweighs similar jumping to
opt-out of it by a large number of noobs.

Also, related to (3), there was that famous Fedora upgrade fiasco a few
Fedora releases back. It went like this:

* A default installation included LVM for all partitions, except
  for /boot, since grub couldn't read inside LVM.
* Six months later, the upgrade process to the next release of Fedora
  happened to require a lot of space in /boot, more than the default
  settings.
* The /boot partition, being the only one outside LVM, was the only one
  that couldn't be resized on-the-fly.
* People who opted-out of LVM usually didn't have a reason to create a
  separate /boot partition, but bundled it under /, circumventing the
  size issue in advance without even knowing it.

So the story ended up with lots of people in upgrading griefs purely
because they couldn't resize the separate /boot partition, and it was
separate because LVM was present, and LVM was present with the goal of
making partition resizing easy! A textbook example of a catch-22,
unbelievable!!

Of course, I know what you'll say --- it wasn't just LVM, but an
unfortunate combination of LVM, limitations of grub, bad defaults and a
lousy upgrade mechanism. And yes, you'd be right, I agree. But the
bottomline was that people with LVM couldn't upgrade (without bending
backwards), while people without LVM didn't even notice that there is a
problem. And since hatred is an irrational thing, you need not look any
further than that. ;-)

Best, :-)
Marko

On 06/23/2015 09:15 AM, Jason Warr wrote:
>> That said, I prefer virtual machines over multiboot environments, and I
>> absolutely despise LVM --- that cursed thing is never getting on my
>> drives. Never again, that is...
>
> I'm curious what has made some people hate LVM so much.
I wondered the same thing, especially in the context of someone who 
prefers virtual machines.  LV-backed VMs have *dramatically* better disk 
performance than file-backed VMs.

On Tue, 2015-06-23 at 11:15 -0500, Jason Warr wrote:
> On 6/23/2015 10:33 AM, Marko Vojinovic wrote:
> > Inside / (which is mostly always ext4), 100% of the time. :-)
> > That said, I prefer virtual machines over multiboot environments, 
> > and I
> > absolutely despise LVM --- that cursed thing is never getting on my
> > drives. Never again, that is...
> I'm curious what has made some people hate LVM so much.  
Having to read the documentation?  That has always been what I assumed 
- people want to do something without being bothered with understanding
what they are doing.
> I have been using it for years on ...
Yep.  Use it on every server, no exceptions, never had issues I did not
cause myself - and moving storage around, adding storage, all on
running servers... never a problem.

-- 
Adam Tauno Williams <mailto:awilliam at whitemice.org> GPG D95ED383
Systems Administrator, Python Developer, LPI / NCLA