ZFS vs RAID, was MyISAM engine: worst case scenario in case of crash (mysql, O/S, hardware, whatever)

Jerry Stuckle wrote:
toby wrote:
toby wrote:

Jerry Stuckle wrote:

...
A failing controller can
easily overwrite the data at some later time. RAID-1 and RAID-10 could
still have that happen, but what are the chances of two separate
controllers having exactly the same failure at the same time?

The difference is that ZFS will see the problem (checksum) and
automatically salvage the data from the good side, while RAID-1 will
not discover the damage


I should have added - you don't need *two* failures. You only need *one
silent error* to cause data loss with RAID-1. ZFS is proof against
silent errors, although of course it's still susceptible to multiple
failures (such as both mirrors suffering a whole disk failure without
repair).


ZFS is not proof against silent errors - they can still occur. It is
possible for it to miss an error, also. Plus it is not proof against
data decaying after it is written to disk.

Actually both capabilities are among its strongest features.

Clearly you haven't read or understood any of the publicly available
information about it, so I'm not going to pursue this any further
beyond relating an analogy:
You will likely live longer if you look both ways before crossing
the road, rather than walking straight across without looking because
"cars will stop".

...
But when properly implemented, RAID-1 and RAID-10 will detect and
correct even more errors than ZFS will.

I'll let those with more patience refute this.


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Jerry Stuckle
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On Sat, 11 Nov 2006, toby wrote:

Jerry Stuckle wrote:
...
But when properly implemented, RAID-1 and RAID-10 will detect and
correct even more errors than ZFS will.

I'll let those with more patience refute this.

Jerry, what are you smoking? Do you actually know what ZFS is, and
if so what if, in the context of your assertion I quoted above, ZFS
is used to implement RAID 1 and RAID 10 (which, incidentally, it is
VERY frequently used to do)?

I agree with Toby: you need to read a bit more about ZFS. If you're
a storage nut (meant in a non-disparaging way!), I think you'll like
what you read.

--
Rich Teer, SCSA, SCNA, SCSECA, OpenSolaris CAB member

President,
Rite Online Inc.

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