Re: mdadm - two questions

[kjonca@poczta.onet.pl (Kamil Jońca)]

Rick Thomas <rbthomas@pobox.com> writes:

> Hi Kamil,
>
> You’d get a bit more space by configuring your 4 drives as a RAID5
> array (3TB usable for RAID5, vs 2TB usable for RAID10).  The downside
> of RAID5 is that the RAID10 (or the one LV with two RAID1 PVs — they
> amount to the same thing for this discussion) can survive loosing two
> drives at once — if they happen to be the right two drives: i.e. not
> both sides of a single mirrored pair — while RAID5 would not be able
> to survive any failure that involved two drives at once.  Either
> configuration would survive loosing any one single drive, of course.
>
> If you want to be able to survive simultaneous loss of any two drives, you should look at RAID6, which would have the same usable capacity (2TB) as the RAID10.

I though about this, but I'm afraid about performance (calculating
control sums ). Needlessly?
KJ

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