Daniel Carosone wrote:
Go with the 2x7 raidz2. When you start to really run out of space,
replace the drives with bigger ones. You will run out of space
eventually regardless; this way you can replace 7 at a time, not 14 at
a time. With luck, each replacement will last you long enough that
the next replacement will come when the next generation of drive sizes
is at the price sweet-spot.
--
Dan.
While that's great in theory, there's getting to be a consensus that 1TB
7200RPM 3.5" Sata drives are really going to be the last usable
capacity. Drives above that simply hit the "too big and too slow"
barrier - that is, they're capacity has outstripped their performance to
a degree that it's actively harmful. Maybe if 15k SAS drives in the
1TB+ range become available (and cheap), they'll be useful, but it looks
like hard drives are really at the end of their advancement, as far as
capacities per drive go.
>1TB drives currently have excessively long resilver time, inferior
reliability (for the most part), and increased power consumption. I'd
generally recommend that folks NOT step beyond the 1TB capacity at the
3.5" hard drive format. Bottom line: while densities of storage are
going up exponentially, throughput is barely linear, and IOPS has
effectively brick-walled. And error rates are actually dropping (i.e.
hard errors per full drive capacity). All of which combine to make the
larger sized drives unreliable enough to avoid them.
So, while it's nice that you can indeed seemlessly swap up drives sizes
(and your recommendation of using 2x7 helps that process), in reality,
it's not a good idea to upgrade from his existing 1TB drives.
Now, in the Real Near Future when we have 1TB+ SSDs that are 1cent/GB,
well, then, it will be nice to swap up. But not until then...
--
Erik Trimble
Java System Support
Mailstop: usca22-123
Phone: x17195
Santa Clara, CA
Timezone: US/Pacific (GMT-0800)
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