Re: partitioned mirror vs. mirrors of partitions?

[Bill Davidsen <davidsen@tmr.com>]

Eric Sandeen wrote:
> Hi, I hope this isn't a FAQ, I did do a little searching first...
>
> I'm looking at using a couple of large disks to mirror a system which
> currently has a few different filesystems; I'll use partitions on the
> disks to contain the different fileystems.
>
> It looks like I could mirror sda and sdb, and partition the resulting
> md_d0.  Or, I could partition sda and sdb, and create mirrors md0, md1,
> etc from the partitions on the underlying disks.
>
> Is there any technical reason to choose one method vs the other?  It
> seems to me that perhaps on a system with several active partitions from
> the same disk, partitioning a single large raid device might allow
> better read balancing?
>   

The reason for going with a partitioned raid is that rebuild after a 
failure is easier. The reason for NOT going there at the moment is 
discussed in another thread here, in the current kernel the partitions 
are not started unless you have an initrd file to make that happen. The 
last is performance, if you are using the partitions in different ways, 
and some would benefit from performance while others (/boot comes to 
mind) need to be simple and reliable, and have minimal requirements for 
speed. Having partitions on the drive allows you to use different raid 
levels across partitions, to best fit what you do with that data.

I don't see any as compelling, there's no one best answer for everyone.

-- 
Bill Davidsen <davidsen@tmr.com>
  "Woe unto the statesman who makes war without a reason that will still
  be valid when the war is over..." Otto von Bismark