Hi Ed,
I believe I have spoken to you in the past as I'm the SouthWest Business Solutions Architect covering the region (including Adam Teeples and Thomas Scanlon). There is obviously a lot going on in the SSD space as far as drives go. Currently there are SLC, eMLC and cMLC drives in the marketplace. The SLC and eMLC (the e stands for enterprise) are best positioned for reliability.
They have the best P/E cycles or (Program and Erase), the higher the P/E cycle the more reliable the drive is. We have traditionally been very conservative and rolled out mainly SLC drives in 100GB sizes but have now replaced them with eMLC drives (sizes ranging from 200GB, 400GB, 800GB and 1.6TB).
Here is some additional information about each drive type (SLC, cMLC and eMLC).
SSD FLASH Technologies
SLC - Single-level Cell
- Enterprise-class media
- Each flash cell represents one binary bit of information
- Nominal rated life: ~ 100,000 erase cycles
MLC - Multi-Level Cell
- Consumer-class media
- Each flash cell represents two bits of information (for improved cost per GB)
- Nominal rated life: ~ 3,000 erase cycles
eMLC - Enterprise Multi-Level Cell
- Term to describe devices that use advanced techniques to achieve longer device life from MLC
- Nominal rated life: ~ 30,000 erase cycles
You can see that the rated life of the SLC and eMLC are superior to the cMLC drives. The way WAFL writes is actually quite a complement to SSD drives allowing us to use the eMLC drives without compromising reliability or data protection. This lowers the cost of the drive and extends the value to our customers without risk.
We also warranty the drives for 5 years ... same as we do for traditional HDDs.
Here is more on the similarities of WAFL to SSD drives:
- Neither writes new data in the same location as old data (no write-in-place updates)
- Both have to deal with garbage collection (delayed free process in WAFL)
- For WAFL ‒ 1% per volume or entire aggregate
- For WAFL ‒ 2% delayed free priority increases
- Both have a staging area and write asynchronously (NVLOG and FTL)
- Both have a physical-to-logical mapping – logical organization differs from physical layout; that can result in spatial locality issues (aging)
- Both hole punch
As far as the roadmap goes I can't commit to anything but there are lots of future technologies we are looking at such as TLC (Triple level Cell) . This is a type of solid-state NAND flash memory that stores three bits per cell of flash memory. It posses a new set of challenges as it's downfall is less performance, reliability, and longevity. This is where some of the NetApp magic comes into play. We currently hold 200+ patents in the flash space and we are always striving to get more out of Flash. If you setup an NDA session with your sales rep we can talk more about this in detail.
I hope this summary has given you some insight into the SSD space and a little glimpse into the future.
Please don't hesitate to reach out to Thomas or Adam and set up an NDA session to discuss this topic in further detail.
Thanks
Ralph
