[SATLUG] lvm2 and raid 0

John Pappas j at jvpappas.net
Mon Jan 7 16:53:35 CST 2008

On Jan 7, 2008 2:47 PM, Chris Lemire <good_bye300 at yahoo.com> wrote:

> I don't know why people are thinking that I said striping has redundancy
> or raid and lvm are the same. I never said either.

Correct.  Reference first reply post by Earnest to your initial question and
my follow-on.  I am not aiming to point, place, troll, or otherwise blame
particular users, groups, sects, or belief structures related to this
conversation.  I interpreted the possibility for confusion on this
reasonably confusing topic, so I was trying to be overly clear.

> I know raid 5 requires 3 drives. I was wondering if it is possible to have
> something similar without 3 drivers. raid 5 offers redundancy and striping.

I do not know of a way to use less than 3 spindles to provide redundancy and
striping.  Bear in mind that reads tend to be faster for R1 than R0 as the
complete dataset resides on both disks and can be used concurrently.  Write
performance suffers in an R1 scenario as the write must be accomplished
twice.  As Brad states, these are generalities, the specifics of your
installation and workloads may have a non-trivial impact on your mileage.

> I've decided to install FC8 without LVM and use software RAID only. I have
> 2 320 gb sata2 drives. Here's what I've decided on.

Solid plan.  I really like LVM, so I would personally find a way to use it,
but it is certainly not required.

/boot in raid 1, / in raid 0, /home in raid 1. As soon as / fails, I don't
> lose anything important, and I can just install something newer than FC8 by
> the time it does. And swap doesn't need to be in RAID. I'll just give each
> swap device the same priority in the /etc/fstab for striping.

Sounds good.

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