OCZ's Vertex 2 Pro Preview: The Fastest MLC SSD We've Ever Testedby Anand Lal Shimpi on December 31, 2009 12:00 AM EST
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Capacities and Hella Overprovisioning
On top of the ~7% spare area you get from the GB to GiB conversion, SandForce specifies an additional 20% flash be set aside for spare area. The table below sums up the relationship between total flash, advertised capacity and user capacity on these four drives:
|Advertised Capacity||Total Flash||User Space|
This is more spare area than even Intel sets aside on its enterprise X25-E drive. It makes sense when you consider that SandForce does have to store more data in its spare area (all of that DuraWrite and RAISE redundancy stuff).
Dedicating almost a third of the flash capacity to spare area is bound to improve performance, but also seriously screw up costs. That doesn’t really matter for the enterprise market (who’s going to complain about a $1500 drive vs. a $1000 drive?), but for the client space it’s a much bigger problem. Desktop and notebook buyers are much more price sensitive. This is where SandForce’s partners will need to use cheaper/lower grade NAND flash to stay competitive, at least in the client space. Let’s hope SandForce’s redundancy and error correction technology actually works.
There’s another solution for client drives. We’re getting these odd capacity points today because the majority of SF’s work was on enterprise technology, the client version of the firmware with less spare area is just further behind. We’ll eventually see 60GB, 120GB, 240GB and 480GB drives. Consult the helpful table below for the lowdown:
|Advertised Capacity||Total Flash||User Space|
That’s nearly 13% spare area on a consumer drive! Almost twice what Intel sets aside. SandForce believes this is the unavoidable direction all SSDs are headed in. Intel would definitely benefit from nearly twice the spare area, but how much more you willing to pay for a faster SSD? It would seem that SandForce’s conclusion only works if you can lower the cost of flash (possibly by going with cheaper NAND).
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Wwhat - Wednesday, January 6, 2010 - linkYou make a good point, and anand seems to deliberately deflect thinking about it, now you must wonder why.
Anyway don't be disheartened, your point is good regardless of this support of 'magic' that anad seems to prefer over an intellectual approach.
Shining Arcanine - Thursday, December 31, 2009 - linkAs far as I can tell from Anand's description of the technology, it seems that this is being done transparently to the operating system, so while the operating system thinks that 25GB have been written, the SSD knows that it only wrote 11GB. Think of it of having two balancing sheets, one that other people see that has nice figures and the other that you see which has the real figures, sort of like what Enron did, except instead of showing the better figures to everyone else when the actual figures are worse, you show the worse figures to everyone else when the actual figures are better.
Anand Lal Shimpi - Thursday, December 31, 2009 - linkData compression, deduplication, etc... are all apparently picked and used on the fly. SandForce says it's not any one algorithm but a combination of optimizations.
AbRASiON - Friday, January 1, 2010 - linkWhat about data reliability, compressed data can normally be a bit of an issue recovering it - any thoughts?
Jenoin - Thursday, December 31, 2009 - linkCould you please post actual disk capacity used for the windows 7 and office install?
The "size" vs "size on disk" of all the folders/files on the drive, (listed by windows in the properties context tab) would be interesting, to see what level of compression there is.
Anand Lal Shimpi - Thursday, December 31, 2009 - linkReported capacity does not change. You don't physically get more space with DuraWrite, you just avoid wasting flash erase cycles.
The only way to see that 25GB of installs results in 11GB of writes is to query the controller or flash memory directly. To the end user, it looks like you just wrote 25GB of data to the drive.
notty22 - Thursday, December 31, 2009 - link
It would be nice for the customer if OCZ did not produce multiple models with varying degrees of quality . Whether its the controller or memory , or combination thereof.
Go to Newegg glance at OCZ 60 gig ssd and greeted with this.
OCZ Agility Series OCZSSD2-1AGT60G
OCZ Core Series V2 OCZSSD2-2C60G
OCZ Vertex Series OCZSSD2-1VTX60G
OCZ Vertex OCZSSD2-1VTXA60G
OCZ Vertex Turbo OCZSSD2-1VTXT60G
OCZ Vertex EX OCZSSD2-1VTXEX60G
OCZ Solid Series OCZSSD2-1SLD60G
OCZ Summit OCZSSD2-1SUM60G
OCZ Agility EX Series OCZSSD2-1AGTEX60G
219.00 - 409.00
Low to high the way I listed them.
I can understand when some say they will wait until the
manufactures work out all the various bugs/negatives that must
be inherent in all these model/name changes.
Which model gets future technical upgrades/support ?
jpiszcz - Thursday, December 31, 2009 - linkI agree with you on that one.
What we need is an SSD that beats the X25-E, so far, there is none.
BTW-- is anyone here running X25-E on enterprise severs with > 100GB/day? If so, what kind of failure rates are seen?
Lonyo - Thursday, December 31, 2009 - linkI like the idea.
Given the current state of the market, their product is pretty suitable when it comes to end user patterns.
SSDs are just too expensive for mass storage, so traditional large capacity mechanical drives make more sense for your film or TV or music collection (all of which are likely to be compressed), which all the non-compressed stuff goes on your SSD for fast access.
It's god sound thinking behind it for a performance drive, although in the long run I'm not so sure the approach would always be particularly useful in a consumer oriented drive.
dagamer34 - Thursday, December 31, 2009 - linkAt least for now, consumer-oriented drives aren't where the money is. Until you get 160GB drives down to $100, most consumers will call SSDs too expensive for laptop use.
The nice thing about desktops though is multiple slots. 80GB is all what most people need to install an OS, a few programs, and games. Media should be stored on a separate platter-based drive anyway (or even a centralized server).