[linux-lvm] LVM2 striping or md raid0

[Kelly Byrd]

On Tue, 25 Sep 2007 14:21:44 -0700, Kelly Byrd <kbyrd at memcpy.com> wrote:
> 
> 
> On Tue, 25 Sep 2007 16:26:30 -0500, Chris Cox <chris_cox at stercomm.com>
> wrote:
>> Kelly Byrd wrote:
>>>
>>>
>>> On Sat, 22 Sep 2007 18:36:41 -0700, Kelly Byrd <kbyrd-lvm at memcpy.com>
>>> wrote:
>>>> Two questions really:
>>>>
>>>> I'm going to use lvm to partition up 4 equal size partitions.
>>>> I can either use the md driver to RAID0 them the make /dev/md0
>>>> my PV, or just use the 4 partitions as PVs and stripe across
>>>> them.
>>>>
>>>> How does lvm2 striping compare with md's RAID0 as far as speed?
>>>> I don't quite get how it stripes on chunk sizes smaller than
>>>> a PE, but a 4MB stripe size seems crazy.
>>>>
>>>> Finally, what's the tuning advice for LVM2 striping? I usually
>>>> create my RAID0 or RAID5 with 128k chunk sizes, is it similar
>>>> for LVM2 striping?
>>>>
>>>>
>>>
>>> anyone?
>>
>> This is merely my own opinion, but md was designed to be
>> THE software raid mechanism.  So, my preference would be
>> to establish a RAID md device and make that into a PV.
>>
>> Of course, I don't believe in non-RAID (i.e. RAID0) anyhow.
>> Maybe someone else will chime in on this one.
>>
>>
> 

I had the same thought, but there's also this instinct that
'one less layer between my files and this physical disk is
better'. I'm really hoping someone will say something like:
'LVM2 striping uses the same code as md raid0' or some other
silly thing.