Hi All,
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).
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?
Thanks...james