Become a SSD expert in minutes! Ryan Smith - - PowerPoint PPT Presentation

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become a ssd expert in minutes
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Become a SSD expert in minutes! Ryan Smith - - PowerPoint PPT Presentation

Dec 07, 2023 143 likes •427 views

Become a SSD expert in minutes! Ryan Smith ryan.smith@ssi.samsung.com 408-205-8889 What is a SSD? SSD = Solid State Drive RAM- based introduced in 1970s Flash- based version in 1990s Today, it typically uses NAND Flash

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Become a SSD expert in minutes!

Ryan Smith ryan.smith@ssi.samsung.com 408-205-8889

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What is a SSD?

  • SSD = Solid State Drive
  • RAM-based introduced in 1970’s
  • Flash-based version in 1990’s
  • Today, it typically uses NAND Flash
  • 2012 is a big year for SSDs
  • Don’t complicate it.. it’s just a really fast drive!

5 10 15 20 25 30 35 2010 2011 2012 Millions

# of SSDs sold

PC Server Storage

Source : Samsung

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Why an SSD?

  • Three things that dictate the speed of your PC/Server:
  • CPU, DRAM, and HDD
  • Everything is speeding up.. Except the HDD

Processor:

  • Multi-core
  • Higher bandwidth

Memory:

  • Larger footprint
  • Higher bandwidth

Storage:

  • Minor throughput improvements
  • Currently solved with spindles

Time Performance Closing the gap with Solid State Storage

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Why an SSD?

  • Lower response times (latency)
  • Higher IOPS and Throughput
  • Lower Power
  • No RVI Issues, More reliable

Random Performance (IOPS) Power Consumption (Watt) Read Write 70:30

Test Environment : Intel SR2600UR Server / IOMeter2008 Test Environment : Intel SR2600UR Server / IOMeter2008 / 4KB RND R70:W30

Active Idle

Source : Samsung

SM825 15K RPM HDD SM825 15K RPM HDD X100 X60 X30

  • 87%
  • 75%

8.5 12.6 3.2 1.1 11K 23K 43K

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So what’s there to know about an SSD?

SSD Key Characteristics SSD Components NAND Characteristics P/E Cycles WAF TBW SMART Host Interface Sustained vs. Peak Performance Benchmarking SSD Influencers TRIM Over-provisioning Changing Workload

MLC

1 1

3,000 User Area

Reserved

O/P

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SSD Key Characteristics

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SSD Components

  • Host/NAND Controller
  • Firmware
  • NAND Flash
  • DRAM
  • Capacitors (optional)

NAND DRAM Firmware Controller

DRAM NAND Flash Controller Firmware Host Interface

All components work closely together

SSD Image Source : Anandtech

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NAND Characteristics

  • Types of NAND
  • TLC
  • MLC
  • E-MLC
  • SLC
  • Geometry / Lithography
  • 4xnm, 3xnm, 2xnm
  • Smaller = Less Cost
  • NAND Hierarchy
  • Pages: Smallest unit that can be read/written (e.g., 8KB)
  • Erase block: Groups of pages (e.g., 64 pages @ 8KB = 512KB)

500-1K P/E Cycles 1 year retention 3-5K P/E Cycles 1 year retention 10-30K P/E Cycles 3 month retention 90-100K P/E Cycles 3 mo – 1 yr retention

TLC

1 1 1

MLC

1 1

E-MLC

SLC

1 1 1

PC Enterprise

1 1 1 1 1 1

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P/E Cycles

  • As geometries shrink, error correction must get better
  • It’s like a car warranty!
  • 3 years or 50,000 miles
  • 3 years or 3,000 P/E Cycles
  • Not a useful characteristic by itself

3,000 3xnm 2xnm 2ynm

ECC Requirements

Program / Erase Cycles

The # of times a given NAND cell can be programmed & erased

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Write Amplification Factor (WAF)

  • WAF 1 means 1MB from host writes 1MB to NAND
  • WAF 5 means 1MB from host writes 5MB to NAND
  • Factors that can affect WAF:

Write Amplification Factor

Bytes written to NAND versus bytes written from PC/Server

Controller

Flash Translation Layer (FTL) Wear Leveling Over-provisioning Garbage Collection

Host Application

Write Profile (Ran vs. Seq) Free user space / TRIM

Bytes written to NAND Bytes written from Host

WAF =

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Write Amplification (WAF) Example

  • Below example illustrates WAF of 6

Z A

LBA 0

Host SSD

Time

B C D E F

LBA 0

A B C D E F

Z B C D E F

Cache Flash

Z Z B C D E F Z B C D E F

Z B C D E F

Host wants to update LBA 0

No more free pages Need to erase entire block Read existing data to Cache Erase block Write modified page and

  • ld pages back to Flash

4KB from Host 24KB to NAND

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TBW

Examples: ((128GB / 1000) * 3000) / 5 = 76.8 TBW ((128GB / 1000) * 3000) / 2.5 = 153.6 TBW ((256GB / 1000) * 3000) / 5 = 153.6 TBW ((128GB / 1000) * 30000) / 5 = 768 TBW

TeraBytes Written

# of terabytes you can write to the drive over it’s useful life

(Capacity GB/1000) x PE Cycles WAF

TBW =

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SMART

ID Attribute Name

5 Reallocated Sector Count 9 Power-on Hours 12 Power-on Count 177 Wear Leveling Count 179 Used Reserved Block Count 180 Unused Reserved Block Count 181 Program Fail Count 182 Erase Fail Count 187 Uncorrectable Error Count 195 ECC Error Count 199 CRC Error Count 241 Total LBA Written

  • Look at health and various statistics
  • Allows for predictable maintenance windows
  • Calculate WAF, TBW
  • Host GB written = [ID241] / (2/1024/1024)
  • NAND GB written = [ID177] * Capacity GB
  • WAF = NAND GB / Host GB
  • Expected Life (yrs) = Warranty PE * ([ID9]/24/365) / [ID177]
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Host Interface

  • This is how you communicate to the SSD
  • So many choices..
  • SATA
  • SAS
  • PCIe (NVMe, SCSIe, SATAe, Proprietary)
  • Which is right for you?

PC Server External Storage SATA PCIe SATA SAS PCIe

SATA + SAS bridge

SAS

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Sustained vs. Peak Performance

  • There can be significant differences in sustained vs. peak
  • Run enterprise benchmark (e.g., SNIA RTP 2.0)
  • Or even better, run your own workload (or simulated)

4KB Ran. R/W 100/0 (NCQ=16) 4KB Ran. R/W 65/35 (NCQ=16) 4KB Ran. R/W 0/100 (NCQ=16)

[IOPS]

[Ran. Performance @ 4KB]

PM830 128GB Value SSD SM825 200GB Mainstream SSD Vendor “X” 160GB Value SSD 1MB Seq. R/W 100/0 (NCQ=16) 1MB Seq. R/W 65/35 (NCQ=16) 1MB Seq. R/W 0/100 (NCQ=16)

[MBs]

[Seq. Performance @ 1MB]

PM830 128GB SM825 200GB Vendor “X” 160GB

Source : Samsung / SNIA RTP2.0 Benchmark

99% below Peak 94% below Peak

Samsung PM830 vs Vendor “X” 11x Sustained Random Writes Samsung PM830 vs Vendor “X” 2x Sustained Sequential Writes

95% below Peak 95% below Peak Over 10,000 IOPS!

There is a BIG difference between “Value” and “Mainstream/Enterprise” SSDs when you have any degree of writes in your workload

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Benchmarking

Benchmark URL

SNIA RTP 2.0

http://www.snia.org/tech_activities/standards/curr_standards/pts

Iometer

http://sourceforge.net/projects/iometer/

ATTO Disk

http://www.attotech.com/products/product.php?sku=Disk_Benchmark

CrystalDiskMark

http://crystalmark.info/software/CrystalDiskMark/index-e.html

HD Tune Pro

http://www.hdtune.com/

AS SSD (SSD)

http://alex-is.de/PHP/fusion/downloads.php?download_id=9

Anvil (SSD)

http://thessdreview.com/latest-buzz/anvil-storage-utilities-releases-new-storage-and-ssd-benchmark/

Scripts Have multiple “dd” running with best guess workload, capturing timing/speeds Real Workload Capture trace during real workload and playback (ioapps, blktrace/btereplay)

  • Synthetic or actual workload & take measurements
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SSD Reviewers

  • Good SSD Review sites available..
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SSD Influencers

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TRIM

  • Helps the SSD know which blocks aren’t used
  • Widely supported standard: Windows, Mac OS X, Linux, hdparm
  • Better sustained performance and extends TBW
  • Without TRIM, SSD only knows block isn’t used once the same

LBA is written to

Hi Hi

Bye

Hi

Bye

No TRIM needed Hi Hi

Bye

Hi

Bye

TRIM makes SSD aware

LBA 0 LBA 0 LBA 0 LBA 0

Host SSD

?

TRIM

Hi

Bye

LBA 0 LBA 0 LBA 0 LBA 1 LBA 1 LBA 0 LBA 1

Time Time

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Over-Provisioning

  • Helps a few things:
  • Improves Write Performance
  • Reduces WAF, Increases TBW

User Area

Reserved

O/P

128GB 100GB

128GB Base-2 to Base-10 conversion: 137,438,953,472 to 128,000,000,0000 (6.9%)

28GB

28% O/P

Sample 128GB SSD 120GB 100GB Over-Provisioning 7% 28% Random Read (8K) IOPS 80K 80K Random Write (8K) IOPS 1,800 6,300 Sequential Read (64K) MB/s 500 500 Sequential Write (64K) MB/s 400 400 4KB Random WAF 5 1.35 4KB Random TBW 15 45

  • 73%

3x 3.5x

These performance numbers are fictitious but do represent the actual benefits seen during tests

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Change Write Workload

  • Write sequentially instead of random to reduce WAF
  • If you have control of the I/O to the disk, this will pay off
  • Align your writes with the page boundaries (e.g., 8KB)
  • If alignment is too hard to implement, just increase your IO size

Only 1 Page needed 2 Pages needed Random Sequential MLC 512GB SSD 60 TBW 1250 TBW

20x

8K 8K 8K 8K 8K

LBA 0

LBA 16 LBA 8

LBA 0

LBA 16

8K 8K 8K

LBA 16

Change block alignment

Host SSD

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Applications of SSDs

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HDD Replacement

  • Replace boot drive or main storage
  • Fastest and easiest way to experience SSDs

SSD

HDD Server HDD

SSD

Storage

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Caching Appliance

  • Read and/or Write Cache
  • Sits between servers and storage, typically in a SAN
  • Used to speed up legacy or slower storage

HDD

SSD

Servers Cache Storage

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Tiered Storage

  • An external storage device (NAS, SAN)
  • Only puts “hot” or “critical” data on SSD
  • Most of the storage is still on HDD

SSD

Servers HDD HDD Storage

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All Flash Storage

  • External storage based on 100% SSD/Flash
  • Typically uses MLC and de-duplication/compression to

achieve better pricing

  • Designers of these systems are Flash experts

SSD SSD SSD

Servers Storage

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New Green Memory App Available