[clue-tech] Software RAID

[Russell Glissmann]

On 6/6/05, Keith Hellman <khellman at mcprogramming.com> wrote:
> On Sat, Jun 04, 2005 at 09:11:03PM -0600, Russell Glissmann wrote:
> > drives into two identical sets (sda1: 100M, sda2: 500M, sda3:
> > remainder size).  Then I create a raid device for each (md0: /boot,
> > md1: swap, md3 /).  The install goes on its merry way using Grub as
> > the boot manager.  On restart everything boots up just fine.  If I
> Raid for swap?  I see how it is technically feasible but is there really
> a reason to do this?  If this is s/w raid and you can't hotswap, isn't
> the swap contents useless after a reboot?
> 
That is true.
> I realize I'm not addressing your question.  I have never used s/w raid,
> so I'm truly curious about raiding swap.
>
 
> Is the swap partition just redundancy?  In this case reading a page back
> into the kernel could be serviced from either drive, is the the reason
> to raid swap?
> 
The only reason I'm putting the swap partition on a RAID is for the
simple reason that I never have to remember to change the swap
partition if / when a drive dies.  I only have to rebuild the RAID for
everything to come back to normal.  At any rate, what difference does
it make to read a swap from a physical device, rather than two
physical devices?  Since this is a mirror, we're reading the same
information from both drives at the exact same time.  So there
shouldn't be a significant time savings by having swap on a physical
drive, compared to the RAID.  Unless my understanding of RAID is not
entirely correct.

Russ
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