Re: Software raid OK?

[Michael Iatrou <m.iatrou@freemail.gr>]

When the date was Monday 20 April 2009, Douglas A. Tutty wrote:

> On Mon, Apr 20, 2009 at 03:29:00PM +0300, Michael Iatrou wrote:
> > When the date was Monday 20 April 2009, BAGI Akos wrote:
> > > Hi List!
> > >
> > > I installed a software raid, level1 with 3 disks, one of them is a
> > > spare.
> > >
> > > I have 2 partitions:
> > > md0 is for / and is made of sda1,sdb1, sdc1
> > > md1 is for swap and made of sda2,sdb2, sdc2
> >
> > There is no particularly good reason to have the swap on RAID. You
> > should define three independed swap partitions; if disk fails, kernel
> > will use the other available.
>
> If swap fails, what happens if something important to the running of the
> system (not just a user app) is swapped-out?  I've seen advice on this
> list many times that to avoid a crash, if other system stuff is on raid,
> that swap should be as well.

I cannot confirm that; instead I am assuming a workflow like the following:

1. A disk is about to fail
2. Notification from SMART hits sysadmin's mailbox
3. # swapoff /dev/sdXY
4. Replace disk, create partitions
5. # swapon /dev/sdXY
6. # mdadm /dev/mdK -a /dev/sdXZ

-- 
 Michael Iatrou