[wplug] Help deciding a RAID+LVM+LUKS setup

[Alheid, Gregory]

Justin,

With a 2TB drive already, I would go one of two ways with LVM using RAID 1.

I  Get a second 2TB drive and 4TB drive;
    1 If the 2TB drive you have is not under LVM,
      A Add  4TB to system, setup as a 4TB LV under LVM but do not MAX out
         and copy present 2 TB to it, after verifying data
      B Move old 2TB to LVM in same VG,
      C Add new 2TB drive in same VG,
      D Setup mirror (RAID 1) of the two 2TB drives to 4TB LV,
         the two 2TBs free space may be less or more than on the 4GB LV
         but once mirrored can be increased to the smaller of the two.
      E Extend ext 3/4 file-system to size of LVs
        (You can move to the below configuration if you get a 2nd 4TB drive later)

II Get a second 2TB drive and two other drives of same size (two 2TBs, 3TB or 4TBs);
    1 If the 2TB drive you have is not under LVM,
      A Add new 2TB to system, setup as a 2TB LV under LVM
         and copy present 2TB to it, after verifying data
      B Move old 2TB to LVM in same VG,
      C Setup mirror (RAID 1) of the two 2TB LVs
      D Add 2nd pair of new drives to same VG
      E Extend LVs of the original LVs to new LVs.
      F Extend ext 3/4 file-system to size of LVs

Greg

-----Original Message-----
From: wplug-bounces+alheidgj=upmc.edu at wplug.org [mailto:wplug-bounces+alheidgj=upmc.edu at wplug.org] On Behalf Of Justin Smith
Sent: Sunday, July 21, 2013 11:31 PM
To: wplug at wplug.org
Subject: [wplug] Help deciding a RAID+LVM+LUKS setup

Anyone who’s met me in person knows that I take great pride in my little
CentOS server. I built it last fall when I got the itch to start running my own
services. Before I knew it, I was using the server for a file server as well,
and the space has really filled up. A single 2 TB drive only gets you so far,
you know?

I need to expand the storage, and I’ve heard that LVM pairs well with RAID.
I also want to redo my disks with dm-crypt+LUKS to keep everything secure.
So basically, I’m looking at RAID + LUKS + LVM...not necessarily in that
order. (I’ve got a 64gb SSD as the OS drive, so there’s no need to take
that into consideration. We’re strictly talking about a storage array here.)

I just can’t make up my mind up on the hard disk configuration. I do know
that I want redundancy and software RAID. I’d  like to mitigate risk, and
that means not subjecting myself to vendor lock-in from a hardware
controller just to get a negligible (for my purposes) performance boost.

But which level of RAID should I use? The horror stories about RAID 5 are
unnerving; on the other hand, I probably don’t have enough drive slots to
have a RAID 10 array of any appreciable capacity unless I remove the 2TB
drive and buy a quartet of 3 or 4 TB drives. How shall I put this.../that’s
expensive/.

My server’s mini-ITX motherboard has 6 SATA slots. The SSD takes up one,
which leaves me room for 5 drives. I could probably fit another one in the
case if I bought a PCI-e SATA controller.

Any ideas, guys?

--
*Justin S. Smith*
Vice chair/secretary, WPLUG Board of Directors
http://www.wplug.org[1]

/"Isn't it ironic that the proprietary software developers call us
communists? We are the ones who have provided for a free market, where
they allow only monopoly."/
-Richard Stallman

--------
[1] http://www.wplug.org
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