Deep Dive: Maximizing EC2 & EBS Performance

Deep Dive: Maximizing EC2 & EBS Performance Tom Maddox, Solutions Architect 2015, Amazon Web Services, Inc. or its affiliates. All rights reserved

What we ll cover Amazon EBS overview Volumes Snapshots Performance Understanding I/O 6 key considerations Q&A

Amazon EBS Overview

For most builders AWS is get in and go!

A normal hard drive Vendor Seek Average, Model Number Read (ms) Average Data Rate, Seek Average, Read / Write (MB/s) Write (ms) Spindle Speed Heads / Disks Interface Options Max Sustained Data Supported SATA Rate (MB/s) Transfer Rates Cache Size (MB) Bytes per Sector

EBS!=

What is EBS? It s a service providing network block storage Volumes can be associated with EC2 instances in the same Availability Zone Designed for five nines of availability Provides point-in-time snapshots to Amazon S3

A few definitions IOPS: Input/output operations per second (#) Throughput: Read/write rate to storage (MiB/s) Latency: Delay between request and completion (ms) Capacity: Volume of data that can be stored (GiB) Block size: Size of each I/O (KiB)

EBS volume types General Purpose (SSD) Provisioned IOPS (SSD) Magnetic When performance matters, use SSD-backed volumes

EBS General Purpose (SSD) volumes Recommended for: default usage where high performance is occasionally required. Throughput: up to 160 MB/sec IOPS: 3 per GB provisioned up to 10,000. Smaller volumes can burst to 3,000 IOPS for periods relative to their size Latency: 1-2ms

Understanding General Purpose (SSD) bursting Max I/O credit 5.4 Million Always accumulating 3 I/O credits / GB / second Can consume up to (3,000 3*GB) I/O credits / second Consumed IOPS Baseline Performance 3 IOPS / GB 11

Comparing instance boot times US East m3.medium boot time comparison Volume type Boot time Access time OS GP2 3:31 4:33 Windows Server 2012 Magnetic 4:30 7:16 Windows Server 2012 GP2 0:36 0:45 CentOS6 Magnetic 0:57 1:16 CentOS6 Up to 40% reduction in boot times by using General Purpose SSD

Database volume selection PIOPS 1x 1TB volume 4,000 Provisioned IOPS $526.40 per month General Purpose 2x 500GB volumes 3,000 baseline IOPS 6,000 peak IOPS! $102.40 per month 80% cost savings and 50% more peak I/O with multiple General Purpose SSD volumes

EBS PIOPS (SSD) volumes Recommended for: I/O intensive databases that require highest consistency Throughput: up to 320 MB/sec IOPS: Provision up to 20,000 IOPS per volume (supports max IOPS:GB ratio of 30:1) Latency: 1-2ms Designed for 99.9% performance consistency

EBS Magnetic volumes Recommended for: cold workloads (rarely accessed data that needs always on access) Throughput: variable by workload (best effort to 10s of MBs) IOPS: ~100 IOPS steady-state, with best-effort bursts Latency: Varies Reads typically ~20-40 ms Writes typically ~2-10 ms

EBS volume types summary General Purpose (SSD) Provisioned IOPS (SSD) Magnetic Recommend use cases Boot volumes Small to med DBs Dev and test I/O-intensive Large DBs Cold storage Storage media SSD-backed SSD-backed Magnetic-backed Volume size 1 GB - 16 TB 4 GB - 16 TB 1 GB - 1 TB IOPS per volume 10,000 IOPS 20,000 IOPS ~100 IOPS Burst < 1 TB to 3000 IOPS n/a n/a Read and write peak throughput 160 MB/s 320 MB/s ~50-90 MB/s 16k IOPS per EC2 node 48,000 48,000 48,000 Throughput per node 800 MB/s 800 MB/s 800 MB/s Latency (random read) 1-2 ms 1-2 ms 20-40 ms API Name gp2 io1 standard Price* $.10/GB-month $.125/GB-month $.065/provisioned IOPS $.05/GB-month $.05/ 1M I/O

Benefits of using EBS snapshots More durable than an EBS volume Stored in Amazon S3 Differential (space-efficient) First snapshot includes all written blocks Subsequent snapshots include changed blocks Pay only for what you use Availability Zone independent Clone to volumes in any neighboring AZ Can be copied efficiently across regions

EBS Performance

Queuing theory Little s law Little s law is the foundation for performance tuning theory. (Mathematically proven by John Little in 1961) L = A * W Where L = Queue length (the average number of requests waiting) A = Request arrival rate W = Average amount of time requests are queued EBS performance is reflective of this law

Performance optimization is measured by: IOPS: Read/write I/O rate (IOPS) Latency: Time between I/O submission and completion (ms) Throughput: Read/write transfer rate (MB/s); throughput = IOPS X I/O size

Tools available for performance tuning: 1. EC2 instance: Network bandwidth (Mbps) 2. EBS-optimized instance: EC2 instance option (On/Off) 3. Workload: Block size, read/write ratio, serialization 4. Queue depth: The number of outstanding I/Os 5. RAID: Stripe volumes to maximize performance 6. Pre-warming: Eliminate first-touch penalty

The life of EBS I/O operations 2. I/O 1. EC2 instance 3.Network link 4. EBS

EC2 instance type selection C3 instance family overview Instance Type vcpu Memory (GiB) Networking Performance EBS Optimized c3.large 2 3.75 Moderate - c3.xlarge 4 7.5 Moderate Yes c3.2xlarge 8 15 High Yes c3.4xlarge 16 30 High Yes c3.8xlarge 32 60 10 Gigabit - Select the EC2 instance that has the right network, RAM, and CPU resources for your applications

EBS-optimized Most instance families supports the EBS-optimized flag EBS-optimized instances now support up to 4 Gb/s Drive 32,000 16K IOPS or 500 MB/s EC2 *.8xlarge instances support 10 Gb/s network Max IOPS per node supported is ~48,000 IOPS @ 16K I/O Use EBS-optimized instances for consistent EBS performance

Workload I/O size: 4 KB to 64 MB I/O type: Read and write I/O pattern: Sequential and random I/O concurrency: Number of concurrent I/O EBS SSD-backed volumes measure I/O size up to 256 KB EBS SSD-backed volumes deliver same performance for read and write

EBS IOPS and throughput limits 20,000 IOPS You can achieve 20,000 IOPS when driving smaller I/O operations 20,000 IOPS PIOPS volume 320 MB/s throughput You can achieve up to 320 MB/s when driving larger I/O operations

EBS IOPS and throughput limits 8,000 IOPS 16,000 X 8 KB = 128 MB/s 8,000 IOPS PIOPS volume 320 MB/s throughput 8,000 X 8 KB = 64 MB/s 8,000 X 16 KB = 128 MB/s 8,000 X 32 KB = 256 MB/s 8,000 X 64 KB = 512 MB/s 1,250 x 256 KB = 320 MB/s Block (I/O) size determines whether your application is IOPS bound or throughput bound

Queue depth Queue depth is the number of pending I/O operations for a volume An I/O operation EC2 EBS After it s gone, it s gone

I/O latency Elapsed time between I/O submission and its completion time Performance requirements may be driven by IOPS or latency or both There is an interdependency among IOPS, queue depth, and latency

Random read latency 40 35 Random read latency across various queue depths 35.1 Latency TP90 (ms) 30 25 20 15 10 5 0 Latency (TP90) 0.075 1 4 8 12 16 20 24 28 32 Queue depth Read latency linearly increases with increase in queue depth

Random read latency Latency TP90 (ms) 35 30 25 20 15 10 5 0 Random read 16 KB IOPS, latency across various queue depths 4,152 35.1 3,851 1,865 0.075 2.09 Latency (TP90) Avg Read IOPS 1 4 8 12 16 20 24 28 32 Queue depth 4,500 4,000 3,500 3,000 2,500 2,000 1,500 1,000 500 - IOPS Queue depth of 1 has the lowest latency, but also has the lowest IOPS

Random read latency Latency TP90 (ms) 35 30 25 20 15 10 5 0 Random read 16 KB IOPS, latency across various queue depths 35.1 4,152 3,851 1,865 2.09 0.075 Latency (TP90) Avg Read IOPS 1 4 8 12 16 20 24 28 32 Queue depth 4,500 4,000 3,500 3,000 2,500 2,000 1,500 1,000 500 - IOPS

Key EBS Volume Metrics Average queue depth Throughput percentage Average read/write size Consumed read/write IOPS Average read/write latency

Latency: baseline Log scale p75 Median p25

Latency: General Purpose SSD volume

Latency: Latest generation instance

Use SSD volumes with latest-generation EC2 instances Optimal queue depth to achieve lower latency and highest IOPS is typically between 4-8; ~1 queue depth per 500 IOPS EBS-optimized instances provide consistent latency experience

RAID (or volume striping) Do Use to extend beyond 16TB volume capacity Use to surpass 320MB/s or 20k IOPS single volume performance limits Don t Mix volume types Configure RAID for redundancy (e.g. RAID-1)

Maximum performance per instance 12 400 GB PIOPS, pre-warmed, RAID 0 LVM, stripe size 128 KB, attached to CR1 instance I/O Pattern Block Thread Write Write Read Read Sizes IOPS BW (MB) IOPS BW (MB) Sequential How should you think about taking snapshots on a striped volume? Quiesce file systems and take snapshot Unmount file system and take snapshot Use OS-specific tools 4K 8 33,500 134 48,250 193 16K 8 13,875 222 48,063 769 1M 1 247 247 823 823

Pre-warming EBS volumes may incur first-access penalty (5-50% performance reduction in IOPS and latency) whilst provisioning continues in background. Pre-warming is the name given to intentionally accessing each block; ensuring a consistent performance level is reached. Pre-warm new volumes before benchmarking by using: Linux: DD write Windows: NTFS full format Always check latest documentation http://docs.aws.amazon.com/awsec2/latest/userguide/ ebs-prewarm.html

Recap: Tools available for performance tuning 1. EC2 instance: Network bandwidth (Mbps) 2. EBS-optimized instance: EC2 instance option (On/Off) 3. Workload: Block size, read/write ratio, serialization 4. Queue depth: The number of outstanding I/Os 5. RAID: Stripe volumes to maximize performance 6. Pre-warming: Eliminate first-touch penalty

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