Re: [gentoo-user] LVM (Was: the best filesystem for server: XFS or JFS (or?))

[Dale]

Alan McKinnon wrote:
> On Saturday 26 March 2011 15:06:31 Elaine C. Sharpe wrote:
>
>>> Just because something works for most people, doesn't mean it will for
>>> everyone either.  If you lose data, it doesn't matter.  LVM just adds
>>> one more layer of something to go wrong.  Me, I don't need the extra
>>> risk of having a system that doesn't boot and a loss of data.  I'm sure
>>> there are a lot of people that see it the way I do too.  They just
>>> don't
>>> need the extra risk.
>>>
>> Using the least number of layers of abstraction you can get away with is
>> a perfectly valid criteria. What I was pointing out was that informal
>> polls of users with a sad story to tell is not a very effective way to
>> conduct research. People say all kinds of things that just aren't true.
>>
> There's an elephant in this room. The number of actual layers is greater than
> just LVM plus FS. It's whatever the BIOS (or a reasonable substitute is
> doing), plus the drive firmware, kernel driver(s) - there's more than one of
> those - plus any RAID in use (hardware or software) and finally the file
> system.
>
> That's a lot of layers, a lot of code, a lot of opportunity for people to
> reveal the extent of their lack of knowledge. I've often heard it said that
> code like ZFS and brtfs eliminates several of these layers therefore it's
> technically a better option. That may be true, but let me just point out that
> whatever LVM+fs+other_stuff is doing as separate chunks of code also gets done
> by ZFS etc. You just don't see it, and just because it's abstracted away
> doesn't mean it's not there.
>
>

I'll add this.  Alan if I recall correctly runs a lot of systems.  He 
has a boatload of experience using all sorts of software/hardware.  Me, 
I don't.  For the longest, I had one system and that was it.  If I 
upgrade my kernel, LVM, or some package that LVM depends on and I can't 
boot, I'm screwed.  If I can't boot, I can't google anything to find out 
how to fix it.  I also don't know enough about LVM to fix it myself.  
Since there is so many layers of things that can already go wrong on a 
system, adding one more layer that can be complicated only makes a 
problem grow.

I'm sure Alan and many others could go out and buy or build a new system 
and put LVM on it and fix about any problem that comes along.  Thing is, 
there are others that can't.  Add to this that when I was thinking about 
using it, I read where a lot of people, for whatever reason, couldn't 
get it back working again and lost data.  For me, I don't care if it was 
LVM itself, the kernel or some combination of other things, if I can't 
boot or lose data, the result is the same.  I can fix a kernel problem, 
a broken package but if LVM fails, I'm stuck.

That said, I now have a second rig.  I may at some point use LVM because 
I can always go to the other room and use my old rig to get help.  I 
already have a 750Gb drive that is about full of pictures, I got a 
camera and get a little happy at times, and videos I have downloaded, 
everything from TV series to stuff off youtube.  I may buy another large 
drive and use LVM or something to give me more room since I really don't 
want to have to break up my filing system across two separate drives.  I 
won't consider putting the booting part of my OS on LVM tho.

Of course, I did see a 3Tb drive on sale the other day at newegg.  o_O  
That would last a while.  ;-)

Dale

:-)  :-)