Antonio da Silva Martins Junior wrote:
>
> ----- "James Olin Oden" <james.oden@xxxxxxxxx> escreveu:
> > For quite some time I've used raid 1 as a means of providing a
> > rollback mechanism for an upgrade (which I learned from others long
> > ago). So essentially, before an upgrade you split the mirrors and
> > upgrade one side or the other. If your upgrade goes well you sync
> > one way, if your upgrade does not you sync the other (much
> hand waving
> > and chanting going on, as its more complicated than that,
> but that is the
> > essence of the solution).
>
> Nice, I didn't think on this before... Will make a try :)
>
> > Recently, I was asked to do the same thing but with a raid 1+0
> > solution. Its easy, enough to break the raid 1 volumes underneath,
> > but then how do I use the broke off volumes to form the
> duplicate strip.
> > Pictures may help.
> > We start off looking like:
> >
> > /----------- Raid 0 Volume ----------\
> > | [disk 0]<---R 1--->[disk 2] |
> > | |
> > | [disk 1]<---R 1--->[disk 3] |
> > \--------------------------------------------/
> >
> >
> > What we want to go to is:
> >
> > /--- Raid 0 ---\ /--- Raid 0 ---\
> > | [disk 0] | | [disk 2] |
> > | | | |
> > | [disk 1] | | [disk 3] |
> > \-----------------/ \------------------/
> > Old System New System
> >
> > Is this possible with the current set of mdadm tools?
>
> Humm... didn't know if it's possible, but IMHO it'll be much
> easier to
> do if you use a 0+1 RAID instead of a 1+0 schema :)
I would start looking at LVM and mirroring the LV to another,
break it, upgrade the LV and if that doesn't work switching
over to the working LV.
Or try a solution with snapshots...
-Ross
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