[Gllug] Partioning advice needed

[Anthony Newman]

Chris Bell wrote:
> On Fri 16 Feb, Nix wrote:
> 
>> The *right* thing to do is to ditch the lot and go LVM, one VG per
>> physical disk, probably (and if you can afford it, get extra disks and
>> go LVM-on-RAID across all of them at once ;) ).
>>
>    Does LVM alone, without RAID, make the filesystem more vulnerable?

If you have more than one physical disk available, it must since you 
have multiple critical underlying devices providing a single file system.

LVM isn't the ultimate panacea despite its potential usefulness, 
especially as there are not any file systems available[0] that allow 
shrinking, so the only way to provide extra space to a logical volume 
when you runs out of space is to expand into space you haven't already 
allocated (and consequently was wasted), or add physical volumes, which 
should also be redundant. If you're running machines that absolutely 
must not go down, it can get you out of a spot, but for people who 
reboot every day it's an extra hassle that you'd have to evaluate on the 
basis of the extra work and the difficulty added to system recovery if 
you have, say, a botched kernel upgrade. LVM alone is little better than 
a JBOD or RAID0 array (the latter as LVM also supports striping).

The option exists now in the kernel (again experimental) to add devices 
to an existing software RAID5, which has potential use, but RAID5 is a 
bit sucky for a variety of reasons.

Compared to commercial storage options, which effectively provide highly 
flexible redundant storage in software, Linux RAID/LVM has a way to go yet.

I'm sure many will disagree :)


Ant


[0] Maybe there are experimental ones, but not that I'd use for any data 
I care about
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