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Re: RAID suggestions?



On Tue, Mar 18, 2008 at 04:33:19PM -0500, Ron Johnson wrote:
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> On 03/18/08 16:03, Damon L. Chesser wrote:
> > Ron Johnson wrote:
> >>
> >> On 03/18/08 15:41, Damon L. Chesser wrote:
> >> [snip]
> >>  
> >>> changes in HD tech).  6.  I have seen dozens of catastrophic  hardware
> >>> controller failures with complete data lost and not one mdadm failure.
> >>>     
> >>
> >> That just means you're using sucky hardware.  We've been using h/w
> >> controllers for 15 years, and never had a problem.
> >>
> >> Of course, they are proprietary, and from a Tier 1 vendor, cost a
> >> lot of money, and maintenance fees are high.
> >>
> >> But we've never lost data from a controller failure.  (And damned
> >> little loss from any other reason, either, since there's a 24x7
> >> admin staff that pays attention to drive failure lights, and
> >> replaces them immediately.)
> >>
> > And that detailed care makes all the difference in the world!  Now limp
> > along with a drive failure, add a controller that needs updating and
> > perform the update.  Suddenly you find the meta data is "unstable" and
> > you can not recover from it.  I have NOT seen data loss from a
> > professional, on the ball data center.
> 
> Well heck, no one who cares about his data would do that...  You
> replace the drive, let it rebuild, and *then* do the update.
> 
> Or... don't buy sucky h/w in the first place.  If you *really* care
> about your data, you spend the extra bucks for quality h/w that has
> a competent support staff behind it.  And you pay for an adequate
> backup solution!
> 
> Otherwise, "you" are blaming on the h/w the sins of the humans who
> bought the crummy h/w.

See, here's the thing. That I in RAID is for inexpensive. The idea is to
increase reliability on the cheap. You could engineer an amazing HD with a
MTBF rating of 150 years (hyperbole, but you get the point), but it would
be hideously expensive. Unless you are using RAID to improve I/O rather
than for redundancy, putting expensive hardware into the equation defeats
the purpose of a RAID in the first place.

Since I don't have major I/O performance requirements, just redundancy
requirements, I use software RAID. I probably always will. I know that even
if 3ware (for example -- replace with the name of your favorite HW RAID
manufacturer) goes out of business, my computer catches fire, and one of my
mirrored drives dies, I can buy an off-the-shelf system, install Debian,
and rebuild my RAID.

> Ron Johnson, Jr.
--Greg


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