Harold Ancell wrote:
At 04:41 AM 5/5/2007, Christian Rost wrote:
My Question now:
Is the second way reasonable or do i missing some things? Anything else to consider?
Mirroring is the simplest way to expand in size and performance.
Pardon me for jumping into a group I just joined, but I sense you are
asking sort of a "philosophy of buying" question, and I have a different
one that you may find useful, plus a question I'd like to confirm from
my reading and searching of this list so far:
For what and when to buy, I observe two things: at some point you
HAVE to buy something; with disks exceeding Moores Law (aren't they
at about a doubling every 12 months instead of 18?), you're going to
feel some pain afterwards *whenever* you purchase as prices continue to
plummet. From that, many say buy what you have to buy when you have to,
although that isn't so useful if growing a RAID-Z is difficult....
Disk prices remain constant. Disk densities change. With 500 GByte disks
in the $120 range, they are on the way out, so are likely to be optimally
priced. But they may not be available next year. If you mirror, then it
is a no-brainer, just add two.
And now the useful (I hope) observation: try plotting the price
performance of parts like this. When you do so, you'll generally
find a "knee" where it shoots up dramatically for the last increment(s)
of performance. When I buy e.g. processors, I pick one that is just
before the beginning of this knee, and for me (your mileage will
vary :-), I suffer the least "buyers remorse" afterwards.
"buyers remorse" for buying computer gear? We might have to revoke your
geek license :-)
The last time I checked and plotted this out, the knee is between 500
and 750GB for 7200.10 Seagate drives, and we can be pretty sure this
won't change until sometime after 1TB disks are widely adopted---and
500GB makes the math simple ^_^.
BTW, is it really true there are no PCI or PCIe multiple SATA connection
host adaptors (at ANY reasonable price, doesn't have to be "budget") that
are really solid under OpenSolaris right now? This would indeed seem
to be a very big problem in the context of what ZFS and especially
RAID-Z/Z2 have to offer.... I know I've selected OpenSolaris primarily
based on the "pick the software you want to run, and then buy the
platform that best supports it", that software being ZFS (plus I just
plain like Solaris, and don't particularly like Linux, even if I still
curse the BSD -> AT&T change of 4.x to 5.x :-).
Look for gear based on LSI 106x or Marvell (see marvell88sx). These are
used in Sun products, such as thumper.
-- richard
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