Re: [gentoo-user] LVM for data drives but not the OS

Re: [gentoo-user] LVM for data drives but not the OS

[Gregory Shearman]

In linux.gentoo.user, you wrote:
> Neil Bothwick wrote:
>> On Thu, 07 Apr 2011 05:22:41 -0500, Dale wrote:
>>
>>    
>>> I want to do it this way because I don't trust LVM enough to put my OS
>>> on.  Just my personal opinion on LVM.
>>>      
>> This doesn't make sense. Your OS can be reinstalled in an hour or two,
>> your photos etc. are irreplaceable.
>>
>>    
>
> It does to me.  I want to keep things so that if there is a problem, I 
> know how to fix it or can at least get to a point that I can get help on 
> it.  If LVM fails and I can't boot, then I loose everything on LVM 
> because I would have to reinstall from scratch.  If it fails just on my 
> data stuff, I can get help and fix it because I can still boot up and 
> get to my email program.  Also, I have the important stuff backed up to 
> DVD.  I would only loose things that I can download again.  I would just 
> rather avoid that and I'm sure AT&T would agree.  That's a lot of 
> downloading.

I have all my partitions on LVM except the boot partition. I've used LVM
for more years than I could count and have *never* had a failure related
to LVM.

I backup my machines to an external drive (2 backup drives actually)
using rsync.

If I have a failure and cannot boot then I just put in my Gentoo Minimal
CD (which has all the LVM tools available) and I can fix the damage. If
the damage isn't fixable then I can just copy over the backups.

LVM snapshots make live backups a breeze. Backups are always in a
consistent state and I've tested them and they *work*.

-- 
Regards,
Gregory.

Re: [gentoo-user] LVM for data drives but not the OS

[Dale]

Gregory Shearman wrote:
> In linux.gentoo.user, you wrote:
>    
>> Neil Bothwick wrote:
>>      
>>> On Thu, 07 Apr 2011 05:22:41 -0500, Dale wrote:
>>>
>>>
>>>        
>>>> I want to do it this way because I don't trust LVM enough to put my OS
>>>> on.  Just my personal opinion on LVM.
>>>>
>>>>          
>>> This doesn't make sense. Your OS can be reinstalled in an hour or two,
>>> your photos etc. are irreplaceable.
>>>
>>>
>>>        
>> It does to me.  I want to keep things so that if there is a problem, I
>> know how to fix it or can at least get to a point that I can get help on
>> it.  If LVM fails and I can't boot, then I loose everything on LVM
>> because I would have to reinstall from scratch.  If it fails just on my
>> data stuff, I can get help and fix it because I can still boot up and
>> get to my email program.  Also, I have the important stuff backed up to
>> DVD.  I would only loose things that I can download again.  I would just
>> rather avoid that and I'm sure AT&T would agree.  That's a lot of
>> downloading.
>>      
> I have all my partitions on LVM except the boot partition. I've used LVM
> for more years than I could count and have *never* had a failure related
> to LVM.
>
> I backup my machines to an external drive (2 backup drives actually)
> using rsync.
>
> If I have a failure and cannot boot then I just put in my Gentoo Minimal
> CD (which has all the LVM tools available) and I can fix the damage. If
> the damage isn't fixable then I can just copy over the backups.
>
> LVM snapshots make live backups a breeze. Backups are always in a
> consistent state and I've tested them and they *work*.
>
>    

If you know how to do that, then that works.  Right now, I have no 
experience with LVM.  All I know is what I have read which is about as 
clear as mud.  ;-)

Dale

:-)  :-)

P. S.  I wonder why this reply was not threaded with the rest?  I see 
this happen sometimes with other threads.  Always been curious about that.

[gentoo-user] Re: LVM for data drives but not the OS

[James]

Dale <rdalek1967 <at> gmail.com> writes:

> If you know how to do that, then that works.  Right now, I have no 
> experience with LVM.  All I know is what I have read which is about as 
> clear as mud.  

Yes, I agree with you Dale.
The docs on LVM raid and many related issues are
in poor shape, confusing and missing current information.

James

Re: [gentoo-user] LVM for data drives but not the OS

[David W Noon]

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On Fri, 08 Apr 2011 15:50:03 +0200, Dale wrote about Re: [gentoo-user]
LVM for data drives but not the OS:

[snip]
>Ooooh.  Still some progress tho.  lol  So, if I was going to use LVM,
>I create a partition first, either whole drive or part of it then use
>LVM on that?

You use pvcreate to create a physical volume from the partition; this
formats the partition for LVM use, rather than for a filesystem. When
you have enough physical volumes on enough disks -- it's usually one
large PV per disk -- you then use vgcreate to amalgamate those physical
volumes into a volume group.  You can then use lvcreate to allocate
logical volumes within that volume group.

After that, you use mkfs to format each logical volume, as if it were a
partition.  You can then add them to /etc/fstab and mount them as
needed.

Note that the amalgamation of physical volumes into a volume group
allows you to do some neat things: you can "stripe" a logical volume
across multiple physical volumes to improve its I/O bandwidth; your
volume group is what DASD managers call a "concatenation set", which
means its effective size is the sum of the physical volume sizes, so
you can create a logical volume that is bigger than any of the physical
volumes involved.

But before you do any of that fancy stuff, get used to using LVM2 as a
smarter partition manager.
-- 
Regards,

Dave  [RLU #314465]
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dwnoon@ntlworld.com (David W Noon)
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