What is driving the need for solid state storage? Flash is a major disruptor of the storage industry. What is available in solid state technology? What does the future hold?
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2. What is driving the need for Solid
State Storage?
Processor
10,000x performance
improvements
• Frequency
• Multi Core
Memory
•Larger Footprint
•Higher Bandwidth
Hard Disk Storage
2x Performance improvements
• Cheaper $/GB, not faster
1980
Performance
1990 2000 2010
Solid State Storage
100 to 10,000 greater
performance
• Better $/IOP than Hard Disk
3. Flash is a major disruptor to the
storage industry
General Purpose
HDD/SSD
Cost & Capacity
Data Services
Low Latency
High IOPS
Hoping to get
acquired
Forced to make
an acquisition
SSD
Optimized
Flash
Optimized
Non-Volatile
Memory
?
Nascent
market
4. Solid State Technology – What is
out there?
• What does Non-volatile NAND Flash Electronics
Mean
• Non-Volatile Memory
• ROM, E-PROM
• NAND, NOR
• Memristor, PCM (Phase Change Memory) – Storage as Memory
(Future)
• Volatile Memory
• D-RAM
• S-RAM
5. Solid State Technology – Available
today
Attributes
• Faster than HDD storage, slower and cheaper than DRAM
memory
• Writes are slower than reads and can vary with time
Enterprise Types:
• SLC (Single Level Cell): max performance & endurance
• eMLC/MLC (Multi Level Cell): lower cost and endurance.
Commercial Type:
• cMLC or TLC (Three Level Cell – Sometimes referred to as MLC-3): even lower cost,
lower endurance at a device level
6. SLC vs MLC Flash – The Basics
What’s the difference and why does it matter?
SLC Flash MLC Flash
On
Off
On
Mainly On
Mainly Off
Off
7. SLC vs MLC Flash – The Basics
What’s the difference and why does it matter?
SLC Flash MLC Flash
Programmed
Erased
Fully
Programmed
Partially
Programmed
Partially Erased
Fully Erased
2X Capacity
8. SLC vs MLC Flash – The Basics
What’s the difference and why does it matter?
SLC Flash MLC Flash
Programmed
Erased
Fully
Programmed
Partially
Programmed
Partially Erased
Fully Erased
Penalty
9. SLC vs MLC Flash – The Basics
What’s the difference and why does it matter?
SLC
Flash
MLC
Flash
Programmed
Erased
Fully
Programmed
Partially
Programmed
Partially Erased
Fully Erased
Fails up to 10X Faster
~50% slower / performance
MLC
SLC
MLC’s reliability is uncertain after 10K cycles
Product
Use Start Wear
Out
10K P/E Cycle endurance
with 1-bit ECC
Over 10K P/E Cycle
endurance with multi-bit
ECC
100K Program and Erase Cycle endurance
SLC is still reliable after 100K cycles
3PAR massively parallel architecture with enhancements like Adaptive Sparing enable 3PAR to
use MLC (hence lowering the cost of flash) without compromising on performance or endurance
10. SLC vs MLC Flash – The Basics
Attributes
Different grades of NAND flash have different life expectancies. These life expectancies are based on the number
of bits per cell and the die size of the NAND flash technology. These life expectancies are expressed in write
cycles, or number of program-erase cycles per bit
• SLC: ~100,000 write cycles
• MLC-2: 3,000 – ~30,000 write cycles
– cMLC; eMLC*
• TLC/MLC-3: 300 – 3,000 write cycles
SLC
Flash
MLC
Flash
Programmed
Erased
Fully
Programmed
Partially
Programmed
Partially Erased
Fully Erased
* By using advanced low-level flash controllers and other techniques, some SSD manufacturers have taken
regular MLC-2 flash and extended the number of write cycles by a factor of approximately ten, resulting in a
lifetime of 20,000 – 30,000 write cycles per bit.
11. SLC vs MLC vs TLC Flash – The
Basics
SLC vs. MLC vs. TLC as explained with a glass of water
This glass of water analogy demonstrates how SLC NAND Flash outperforms MLC NAND Flash
• SLC Flash has only two states: erased (empty) or programmed (full)
• MLC Flash has four states: erased (empty), 1/3, 2/3, and programmed (full)
• TLC Flash has eight states: erased (empty), 1/7, 2/7, 3/7, 4/7, 5/7, 6/7 and programmed (full)
0
1
SLC
00
01
10
11
MLC
000
001
011
101
TLC
111
010
100
110
It’s easier to read the correct fill status when a glass is either empty or full, as in SLC NAND Flash. When a
glass is partially full, as in MLC NAND Flash, the fill status is more difficult to read, taking more time and
energy.
12. Solid State Technology – so many
choices
• Enterprise Storage Implementations
• Multiple form factor alternatives
• SSD (SLC, eMLC, cMLC, TLC)
• PCIe card
• SST Array
• Hybrid
• Performance varies by measures and across
implementations
• IOPS
• Latency
• Bandwidth
• Metric - $/IOPS, $/GB, $/IOP/U, Latency, R/W mix
13. What does the future have in store
for Flash?
Some consensus predictions
• Flash / SSD / SSS /
NVM / Caching,
you name it, its
happening
• All SSD / All Flash Arrays, startups
and acquisition activity leading to
integration into new and existing
architectures
• Flash tiering will become
mainstream and an expected
baseline
• Caching solutions enter prime time
700000
600000
500000
400000
300000
200000
100000
0
WW HDD Shipments, '000
1976
1981
1986
1991
1996
2001
2006
2011
2016
700000
600000
500000
400000
300000
200000
100000
0
WW SSD
Shipments, '000
1976
1982
1988
1994
2000
2006
2012
Source: Coughlin Associates, May 2012
Sources: Disk/Trend from 1976 to 1998, Trendfocus from
1999 to 2017 (forecast from 2013 to 2017), IDC for 2006
14. Solid State Deployment Models
SSD as a tier of storage
• In storage arrays or
servers
• Multiple capacity points,
max counts
• Multiple technologies: SLC,
MLC
• LUN & Sub-LUN tiering
technologies
SSD optimized arrays
• Flash optimized –
performance, density,
latency, software
» Option for spinning media if
needed
• Virtual SAN Appliance
Hybrid Arrays
• Hybrid - Flash + Spinning Media
• Sometimes application focused (like
Oracle Exadata)
• Typically used to go after general
purpose storage vs all flash arrays
Flash Cache
• Caching copies data; tiering moves
data
• Host based flash caching
• Storage based flash caching
• Collaborative host/storage flash
caching
EMC buys XtremeIO
IBM buys Texas Memory Systems
NetApp buys CacheIQ
SanDisk buys FlashSoft
OCZ buys Sanrad
SSD Form Factors
SSDs can be implemented in several form factors. Although either DRAM or NAND flash could be used for these, NAND flash is the most common type of SSD technology used today. These form factors include:
SSD-specific – Newer form factors specifically designed for SSDs.
Disk drive – Any of the 3.5-inch, 2.5-inch, 1.8-inch, or other sizes of disk drives.
PCIe card – A PCI-Express® card with SSD technology mounted directly on it.
Memory slot – NAND flash can be mounted on 240-pin DIMMs along with a SATA or other storage interface to provide storage in unused DIMM sockets.
Flash is erased in blocks, not a word or bit at a time. The blocks are sized by the flash manufacturer in order to balance silicon area (since each erase block carries a fair amount of overhead circuitry) and ease of use. Because of the logic structure of NAND flash, the flash must also be written or read in fairly large pages, typically 1 K to 4 KB. These pages are written from or read to a page buffer, from which individual byte reads or writes are done. Each erase block contains between 32 and 128 pages
SSDs are dollars per gigabyte and pennies per IOPS.
HDDs are pennies per gigabyte and dollars per IOPS.
Mid level enterprise SLC drives together with intelligent tiering software and wide striping lower $/IOP AND $/GB