lvm or btrfs? which is preferable (when, if applicable)

[Bill Davidsen]

Reindl Harald wrote:
>
>
> Am 20.01.2013 02:00, schrieb Ranjan Maitra:
>> Thanks again for your quick response.
>>
>> OK, so you are suggesting I move to lvm, or leave things as is, to ext4?
>> The new installer does not give me an option to format ext4 (but I can
>> keep it as is, I guess).
>>
>> How does one convert from ext4 to lvm? Is there any benefit to moving
>> to lvm?
>
> you should really read some basic documentations
>
> ext4 is a filesystem
> btrfs is a filesystem
> lvm is NOT a filesystem
>
> you have ext4, btrfs, whatever FS ON TOP of LVM
> http://en.wikipedia.org/wiki/Logical_volume_management
>
> for most private environments there is no real benefit of LVM
> spread LVM over more than one disk with no RAID under it
> is simply dumb becasue if ONE of the disks goes down
> you have a problem
>
Your point about loss of data is well taken, but having data on any storage 
without RAID for error recovery is a risk, having data on just one machine is a 
risk. The admin has to balance cost and benefit, for both hardware and 
administrative learning curve considered as "cost." The benefit of LVM is being 
able to easily move data to other physical devices and expand the size of 
storage. LVM can do RAID by itself, although I have always created arrays with 
mdadm because I'm most familiar with doing it that way.

Note that the user interface to LVM, bad as it is, is still much easier to 
master than adding drives to a RAID array and growing filesystems. In my 
opinion,the fewer commands you need to use the less likely you are to make a 
mistake.

While there are unusual use cases in which btrfs is significantly faster than 
ext4, and btrfs provides some capabilities not in ext4, most users will see 
little benefit from it. The problems btrfs was created to address are not common.

-- 
Bill Davidsen <davidsen at tmr.com>
   "We have more to fear from the bungling of the incompetent than from
the machinations of the wicked."  - from Slashdot