On Dec 22, 2009, at 11:49 AM, Toby Thain wrote:
On 22-Dec-09, at 12:42 PM, Roman Naumenko wrote:
On Tue, 22 Dec 2009, Ross Walker wrote:
Applying classic RAID terms to zfs is just plain
wrong and misleading since zfs does not directly implement these
classic RAID approaches
even though it re-uses some of the algorithms for data recovery.
Details do matter.
Bob
--
Bob Friesenhahn
bfrie...@simple.dallas.tx.us,
I wouldn't agree.
SUN introduced just another marketing names for the well known
things, even adding some new functionality.
raid6 is raid6, not matter how you name it: raidz2, raid-dp, raid-
ADG or somehow else.
Sounds nice, but it's is just buzzwords.
The implied equivalence is wrong and confusing. That's the kind of
mislabelling that Bob was complaining about.
Yes. Also note that the RAID levels have rather strict definitions.
http://www.snia.org/education/dictionary/r
IMHO the biggest difference is the dynamic nature of ZFS. For
example, the definition of RAID-0 (data striping) is:
A disk array data mapping technique in which fixed-length sequences
of virtual disk data addresses are mapped to sequences of member
disk addresses in a regular rotating pattern.
ZFS implements dynamic striping, which is different in that the "fixed-
length
sequences" aren't really fixed and the "regular rotating pattern" is
biased
towards allocations on devices which have more free space. The upshot
is that the space available to a dynamic stripe is the sum of the
space of
the vdevs, whereas for RAID-0 it is N * min(vdev size).
-- richard
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