[Beowulf] SSD prices

Greg Lindahl lindahl at pbm.com
Fri Dec 12 00:18:06 EST 2008


On Thu, Dec 11, 2008 at 11:38:58PM -0500, Robert G. Brown wrote:

> It does look worth noting that one should get SLC and not MLC SSD for
> any "disk like" application.  It's faster (10x faster) and they argue
> much more reliable.  More expensive, too, of course.

Transcend has both MLC and SLC, and they charge 3X as much for SLC, if
NexTag is finding low prices properly. (Incidentally, NexTag claims
the lowest price for a 32G USB stick is about the same as a 32gb OCZ
drive. Hm.)

But Fusion-io's specsheet says that their MLC board is only a little
slower than their SLC board. That's a high-end controller with more
channels, but you'll see that in low-end drives in the next generation.

Perhaps most of the problems people report in the low-end drives might
be crappy firmware on that Jmicron controller everyone hates.
Certainly Apple doesn't seem to have a problem making flash devices
reasonably reliable. But they control all the firmware.

> I'm not sure SSD is perfect for userspace hard storage, but for basic
> operating system images it seems reasonable.  How many times does one
> write to the read-mostly stuff in /, /usr, /lib, /etc?

Not very often, but there's always /var and /tmp and swap to worry
about. The other guys at Blekko had a very bad experience with flash 5
years ago on Linux network appliances at their previous startup. It is
unclear to me if that was a bad batch of flash, or dumb software, or
what.

-- greg

p.s. While I'm at it, I think that these SATA-to-USB gizmos are pretty
cool: http://www.thinkgeek.com/computing/drives/a7ea/?cpg=ab Lots of
people seem to sell 'em.



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