Re: [PLUG] Mirrored drives with LVM

["Mag Gam" <magawake@gmail.com>]

hey Jim

thanks for the reply.

My setup is very different from the OP. I was just intrigued by his LVM write up. I suppose I should start a new thread :-) 

I have 12disk (500GB) disk array. I would like to setup 2 (or 3 or 4)  RAID 5 volumes via controller. Once I setup the volumes, I will create PVs out of them using LVM. The LVs  create I plan on using striping and put ext3 fs. My question is, what would be the optimal setup for performance? Redudancy is important but would like to get good performace because we are planning to do scientific computing for the summer at my University...

On Sat, Jun 7, 2008 at 8:53 AM, James Barrett <jadoba@jadoba.net> wrote:

RAID on HW level - I am supposing you mean two RAID1 arrays?  Striping
with LVM... as in, two physical devices, one VG, and striping...

This is feasible.  I do not see how doing this would be any different
than RAID1+0 or RAID0+1, allowing you to lose two of four disks.  It
just depends on which disks you lose!  If you lose two disks in the
same array, all data is lost.  If you lose one disk in each array, you
still have all data.  Of course, I imagine that using LVM for the
striping allows you to add non-raided disks, which completely defeats
the purpose of using any raided disks.

If you choose RAID6 (2 parity), it will give different results.  You
still have the ability to lose 2 disks, but without discretion on
which are lost.  The downside of RAID6 is decreased performance.

HTH

--
Jim

On Sat, Jun 7, 2008 at 8:30 AM, Mag Gam <magawake@gmail.com> wrote:
> Slightly off topic question ...
> I see you are using RAID on LVM, what if I am using RAID on HW level and I
> plan to stripe on LVM level. Is this a good practice?

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