[GRLUG] RAID levels

[Richard Nienhuis]

To bring this back to its actual application...  Its a personal music server
made from scrap parts.  It doesn't require 5 9's uptime of hands free
operation.  The most likely failure mode of this thing is that one day a
drive will fail on reboot/startup.  Hot spare isn't going to save it from a
second drive failure at startup.  For its application integrity is a
priority over everything else.  Downtime is a relatively inconsequential
cost.

Hot spare is good if you have an extra one available.  In this case the 5
drives are of better use in RAID 6 rather than just having one sitting
around.  If he gets another drive at some point then its painless to add it
as a hot spare.  Plus I don't think saving a few minutes is worth the extra
hassle since if a drive does fail he is probably going to be right there.
 That array will have a rebuild time of 7 hours or so.  Not a big time
savings.

On Sun, Oct 2, 2011 at 8:14 PM, Adam Tauno Williams
<awilliam at whitemice.org>wrote:

> On Fri, 2011-09-30 at 18:55 -0400, Richard Nienhuis wrote:
> > Performance issues are going to be inconsequential for a machine
> > playing  music.  In degraded mode there is probably still enough
> > performance.  Also hot spare isn't going to spare you from the time to
> > rebuild the array.
>
> ????   I just can't express in words how strongly, completely,
> absolutely, and utterly I disagree with the statement: "Hot spare isn't
> going to spare you from the time to rebuild the array."
>
> That is like saying ice is hot and water is dry.
>
> A hot spare means - Rebuilding the array actually starts!!!!
>
> The sooner it starts the sooner it is complete and the redundancy
> underlying the data is restored.  A RAID solution without a hot spare is
> a sports car with only three tires.
>
>
>
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