Re: Solid State Drives with PG

On Fri, 2010-03-26 at 15:27 -0400, Merlin Moncure wrote:
> On Fri, Mar 26, 2010 at 2:32 PM, Greg Smith <greg(at)2ndquadrant(dot)com> wrote:
> > Merlin Moncure wrote:
> >>
> >> So flash isn't yet a general purpose database solution, and wont be until
> >> the write performance problem is fixed in a way that doesn't
> >> compromise on volatility.
> >
> > Flash drives that ship with a supercapacitor large enough to ensure orderly
> > write cache flushing in the event of power loss seem to be the only solution
> > anyone is making progress on for this right now. That would turn them into
> > something even better even than the traditional approach of using regular
> > disk with a battery-backed write caching controller. Given the relatively
> > small write cache involved and the fast write speed, it's certainly feasible
> > to just flush at power loss every time rather than what the BBWC products
> > do--recover once power comes back.
>
> right -- unfortunately there is likely going to be a fairly high cost
> premium on these devices for a good while yet. right now afaik you
> only see this stuff on boutique type devices...yeech.

TMS RamSan products have more than adequate capacitor power to handle
failure cases. They look like a very solid product. In addition to
this, they have internal RAID across the chips to protect against chip
failure. Wear-leveling is controlled on the board instead of offloaded
to the host. I haven't gotten my hands on one yet, but should at some
point in the not to distant future.

I'm not sure what the price point is though. But when you factor in the
cost of the products they are competing against from a performance
perspective, I'd be surprise if they aren't a lot cheaper. Especially
when figuring in all the other costs that go along with disk arrays -
power, cooling, rack space costs.

Depends on the your vantange point I guess. I'm looking at these as
potential alternatives to some high end, expensive storage products, not
a cheap way to get really fast disk.
--
Brad Nicholson 416-673-4106
Database Administrator, Afilias Canada Corp.