The document discusses how flash memory technology can be used to optimize storage infrastructures. Flash has a much lower uncorrectable bit error rate than hard disk drives, allowing for simplification of RAID configurations and reduced data protection overhead. This performance margin of flash can enable hardware consolidation and replacing hybrid hard disk drive/solid state drive arrays with all-flash solutions. While all-flash data centers are possible for workloads involving only hot or warm data, hard disk drives will still be needed alongside solid state drives for many environments due to their lower cost for cold data storage. Flash adoption in data centers will continue to increase as a viable alternative to hard disk drives.

1. Rethinking Storage Infrastructures by Utilizing the Value of Flash
Adam Roberts - Engineering Fellow,
SanDisk Corporation | A Western Digital Company
August 10, 2016
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Flash Memory Summit 2016
Santa Clara, CA

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Forward Looking Statements
During our meeting today, we may make forward-looking statements.
Any statement that refers to expectations, projections, or other characterizations of future events or circumstances is a
forward-looking statement, including those relating to industry trends, expectations that flash will continue to make
gains in data centers, and expectations regarding all-flash data centers. Risks that may cause these forward-looking
statements to be inaccurate include among others: industry trends may not evolve as expected, flash may not
continue to make gains in data centers as expected, and expectations for the advance of flash over HDD in data centers
may be inaccurate; or the other risks detailed from time-to-time in SanDisk Corporation’s and Western Digital
Corporation’s Securities and Exchange Commission filings and reports, including, but not limited to, their respective
quarterly reports on Form 10-Q for the most recently completed fiscal quarter.
This presentation contains statements from third parties. We undertake no obligation to update these forward-looking
statements, which speak only as of the date hereof or the date of issuance by a third party, as applicable
Flash Memory Summit 2016
Santa Clara, CA

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 Better UBER
– Allows simplification of RAID configs
 Performance margin used for parity
calculations
 Hardware Consolidation
– Result of:
• UBER
• Performance
• High capacity point per SSD
– Lower solution costs result
 Optimizing Storage Tiers
– Low cost moderate performing SSDs allow
for replacing HDD/SSD Hybrid arrays with
all flash solutions
Flash Value and Affect
Flash Memory Summit 2016
Santa Clara, CA

4. 4
What is UBER?
• UBER stands for Uncorrectable Bit Error Rate
• UBER quantifies the chance that a bit of data cannot be retrieved from the media, due to
an uncorrectable error that happened while the data was stored or during retrieval
• An UBER of 10-15 means that 1 in every 1015 data reads, an uncorrectable error will
occur
• Enterprise SSDs, depending on the device chosen, are anywhere from 10x to 10,000x less
likely to exhibiting an uncorrectable bit error versus enterprise HDDs.*
Hint: It has
nothing to do
with cars!
Flash Memory Summit 2016
Santa Clara, CA *https://www.sandisk.com/business/datacenter/products/flash-devices/ssds/sas-ssd/lightning-gen2

5. 5
UBER SanDisk Enterprise SSDs
UBER
Rate
SanDisk Enterprise SSD Reliability
Benefit
SanDisk/WD
Enterprise SSD
10-18 Best in Class. How does it compare?
Let’s take a look!
Enterprise SSD 10-17 10x Better than competing Enterprise
SSDs
Enterprise HDD 10-16 100x Better than Enterprise HDD
Client SSD 10-15 1000x Better than Client SSD
Note: SanDisk has some specific products that meet even higher UBER at 10-19 and 10-20 in the Lightning Ultra Gen II and the
Fusion IO PCIe cards respectively
Flash Memory Summit 2016
Santa Clara, CA

6. 6
Uncorrectable Bit Error Rate Approaches Zero
0
20
40
60
80
100
120
Average Bit Loss per
10x1^18 transactions
Enterprise
HDD
Enterprise
SSD
SanDisk/WD
Enterprise
SSD
As UBER approaches zero, expensive redundancy
methods put in place to protect from it can be lessened
• Reduces the need for RAID or redundancy
• Employ frequent snapshots for some use cases
• Remove the need for double buffered writes in
databases, receiving over 2x performance boost
• Allows RAID configuration simplifications
• Erasure coding simplified to RAID 6 or RAID 5
• RAID 6 simplified to RAID 5
• Acts simply as a tie breaker for choosing the best drive!
Flash Memory Summit 2016
Santa Clara, CA

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• Performance Access Density = IOPS/GB
• Higher Access Density can lead to higher HW consolidation
• RAID protection levels affect Access Density
• HDD performance limitations limit device capacity growth
• SSD device capacity continues to grow since application performance access density
needs can still be met
Performance access density needs drive flash adoption
Flash Memory Summit 2016
Santa Clara, CA

8. = 1 drive
Red = redundancy overhead
Blue = usable capacity
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Example: Improving Access Density and Reducing
RAID overhead Data Protection overhead
AKA “unusable purchased
capacity”
50% protection overhead
20% protection overhead
• (24) 1.2 TB HDDs
• Usable capacity 14.4 TB
• (5) 3.84 TB SSDs
• Usable capacity 15.36 TB
• More capacity and 10x better
UBER (Uncorrectable Bit Error
Rate) than the HDD solution
(5 drives) RAID 5
(24 drives) RAID 10
Flash Memory Summit 2016
Santa Clara, CA

9. 2-Tier HDD/SSD Solution vs 1-Tier SSD Solution
SSD Performance margin and better UBER can allow Simplification of Tiers
Flash Memory Summit 2016
Santa Clara, CA

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With the advantages described can flash take over the datacenter?
Probably not
• Flash has and will continue to make huge progress and gains in the datacenter
• HDDs can cover some warm and most cold data at a very efficient cost
• At least for now… the two exist side by side
Flash Memory Summit 2016
Santa Clara, CA

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Flash Memory Summit 2016
Santa Clara, CA

12. Flash Memory Summit 2016
Santa Clara, CA 12
Flash Pool
10k HDD
Moderate SSD Pool
7.2k HDD Pool
Data migration thru the lakes add to
overall endurance needs, affecting
flash cost
Hot Data
Warm Data
Cold Data
Data is pulled downward to a cooler tier
based on age and/or access frequency
Dead Data

13. Flash Memory Summit 2016
Santa Clara, CA 13
Summary:
All Flash datacenter is possible if data set is all hot or warm
For everyone else low cost, low performance HDD solutions will
exist alongside SSD solutions for quite some time
SSDs will absolutely continue to increase footprint as a viable
alternative to HDDs

14. SanDisk Confidential 14
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other countries. Lightning Ultra, CloudSpeed Ultra and Fusion ioMemory are trademarks of Western Digital Corporation or its affiliates. Other brand names mentioned herein are for
identification purposes only and may be the trademark(s) of their respective holder(s).
Thanks!