Amazon Aurora is a MySQL-compatible relational database engine that combines the speed and availability of high-end commercial databases with the simplicity and cost-effectiveness of open source databases. Amazon Aurora is disruptive technology in the database space, bringing a new architectural model and distributed systems techniques to provide far higher performance, availability and durability than previously available using conventional monolithic database techniques. In this session, we will do a deep-dive into some of the key innovations behind Amazon Aurora, discuss best practices and configurations, and share early customer experience from the field.

1. © 2015, Amazon Web Services, Inc. or its Affiliates. All rights reserved.
Anurag Gupta, VP, Aurora, Amazon
Redshift, EMR
October 2015
DAT405
Amazon Aurora Deep Dive
Design Overview of Aurora Performance and Availability
6-way replication across 3 AZsCustom, scale-out SSD storageLess than 30s failovers or crash recoveryShared storage across replicasUp to 15 read replicas that act as failover targetsPay for the storage you useAutomatic hotspot managementAutomatic IOPS provisioning100K writes/second & 500K reads/secondBuffer caches that survive a database restartsSQL fault injectionMySQL compatibleAutomatic volume growthUp to 64TB databasesProactive data block corruption detectionAutomated continuous backups to S3Automated repair of bad disksPeer to peer gossip replicationQuorum writes tolerate drive or AZ failures1/10th the cost of commercial databasesLess than 10ms replica lag6-way replication across 3 AZsCustom, scale-out SSD storageLess than 30s failovers or crash recoveryShared storage across replicasUp to 15 read replicas that act as failover targetsPay for the storage you useAutomatic hotspot managementAutomatic IOPS provisioning100K writes/second & 500K reads/secondBuffer caches that survive a database restartsSQL fault injectionMySQL compatibleAutomatic volume growthUp to 64TB databasesProactive data block corruption detectionAutomated continuous backups to S3Automated repair of bad disksPeer to peer gossip replicationQuorum writes tolerate drive or AZ failures1/10th the cost of commercial databasesLess than 10ms replica lag6-way replication across 3 AZsCustom, scale-out SSD storageLess than 30s failovers or crash recoveryShared storage across replicasUp to 15 read replicas that act as failover targetsPay for the storage you useAutomatic hotspot managementAutomatic IOPS provisioning100K writes/second & 500K reads/secondBuffer caches that survive a database restartsSQL fault injectionMySQL compatibleAutomatic volume growthUp to 64TB databasesProactive data block corruption detectionAutomated continuous backups to S3Automated repair of bad disksPeer to peer gossip replicationQuorum writes tolerate drive or AZ failures1/10th the cost of commercial databasesLess than 10ms replica lag6-way replication across 3 AZsCustom, scale-out SSD storageLess than 30s failovers or crash recoveryShared storage across replicasUp to 15 read replicas that act as failover targetsPay for the storage you useAutomatic hotspot managementAutomatic IOPS provisioning100K writes/second & 500K reads/secondBuffer caches that survive a database restartsSQL fault injectionMySQL compatibleAutomatic volume growthUp to 64TB databasesProactive data block corruption detectionAutomated continuous backups to S3Automated repair of bad disksPeer to peer gossip replicationQuorum writes tolerate drive or AZ failures1/10th the cost of commercial databasesLess than 10ms replica lag6-way replication across 3 AZsCustom, scale-out SSD storageLess than 30s failovers or crash recoveryShared storage across replicasUp to 15 read replicas that act as failover targetsPay for the storage you useAutomatic hotspot managementAutomatic IOPS provisioning100K writes/second & 500K reads/secondBuffer caches that survive a database restartsSQL fault injectionMySQL compatibleAutomatic volume growthUp to 64TB databasesProactive data block corruption detectionAutomated continuous backups to S3Automated repair of bad disksPeer to peer gossip replicationQuorum writes tolerate drive or AZ failures1/10th the cost of commercial databasesLess than 10ms replica lag6-way replication across 3 AZsCustom, scale-out SSD storageLess than 30s failovers or crash recoveryShared storage across replicasUp to 15 read replicas that act as failover targetsPay for the storage you useAutomatic hotspot managementAutomatic IOPS provisioning100K writes/second & 500K reads/secondBuffer caches that survive a database restartsSQL fault injectionMySQL compatibleAutomatic volume growthUp to 64TB databasesProactive data block corruption detectionAutomated continuous backups to S3Automated repair of bad disksPeer to peer gossip replicationQuorum writes tolerate drive or AZ failures1/10th the cost of commercial databasesLess than 10ms replica lag6-way replication across 3 AZsCustom, scale-out SSD storageLess than 30s failovers or crash recoveryShared storage across replicasUp to 15 read replicas that act as failover targetsPay for the storage you useAutomatic hotspot managementAutomatic IOPS provisioning100K writes/second & 500K reads/secondBuffer caches that survive a database restartsSQL fault injectionMySQL compatibleAutomatic volume growthUp to 64TB databasesProactive data block corruption detectionAutomated continuous backups to S3Automated repair of bad disksPeer to peer gossip replicationQuorum writes tolerate drive or AZ failures1/10th the cost of commercial databasesLess than 10ms replica lag6-way replication across 3 AZsCustom, scale-out SSD storageLess than 30s failovers or crash recoveryShared storage across replicasUp to 15 read replicas that act as failover targetsPay for the storage you useAutomatic hotspot managementAutomatic IOPS provisioning100K writes/second & 500K reads/secondBuffer caches that survive a database restartsSQL fault injectionMySQL compatibleAutomatic volume growthUp to 64TB databasesProactive data block corruption detectionAutomated continuous backups to S3Automated repair of bad disksPeer to peer gossip replicationQuorum writes tolerate drive or AZ failures1/10th the cost of commercial databasesLess than 10ms replica lagCommercial Performance at Open Source Prices

2. MySQL-compatible relational database
Performance and availability of
commercial databases
Simplicity and cost-effectiveness of
open source databases
What is Amazon Aurora?

3. 4 client machines with 1,000 connections each
WRITE PERFORMANCE READ PERFORMANCE
Single client machine with 1,600 connections
MySQL SysBench
R3.8XL with 32 cores and 244 GB RAM
SQL benchmark results

4. Reproducing these results
https ://d0.a wsstat ic . com /product -m ark eting/Aurora /R DS_ Auro ra_Perf orm ance_Assessm ent_Benchm ark ing_v 1-2 .pdf
AMAZON
AURORA
R3.8XLARGE
R3.8XLARGE
R3.8XLARGE
R3.8XLARGE
R3.8XLARGE
• Create an Amazon VPC (or use an existing one).
• Create four EC2 R3.8XL client instances to run the
SysBench client. All four should be in the same AZ.
• Enable enhanced networking on your clients.
• Tune your Linux settings (see whitepaper).
• Install Sysbench version 0.5.
• Launch a r3.8xlarge Amazon Aurora DB instance in
the same VPC and AZ as your clients.
• Start your benchmark!
1
2
3
4
5
6
7

5. Beyond benchmarks
If only real-world applications saw benchmark
performance
DISTORTIONS IN THE REAL WORLD
Requests contend with each other
Metadata rarely fits in data dictionary cache
Data rarely fits in buffer cache
Production databases need to run HA

6. Scaling user connections
SysBench OLTP workload
250 tables
Connections Amazon Aurora
RDS MySQL
30K IOPS (single AZ)
50 40,000 10,000
500 71,000 21,000
5,000 110,000 13,000
8x
UP TO
FA STER

7. Scaling table count
Tables
Amazon
Aurora
MySQL
I2.8XL
local SSD
MySQL
I2.8XL
RAM disk
RDS
MySQL
30K IOPS
(single AZ)
10 60,000 18,000 22,000 25,000
100 66,000 19,000 24,000 23,000
1,000 64,000 7,000 18,000 8,000
10,000 54,000 4,000 8,000 5,000
SysBench write-only workload
1,000 connections
Default settings
11x
UP TO
FA STER

8. Scaling data set size
DB Size Amazon Aurora
RDS MySQL
30K IOPS (single AZ)
1GB 107,000 8,400
10GB 107,000 2,400
100GB 101,000 1,500
1TB 26,000 1,200
67x
U P TO
FA STER
SYSBENCH WRITE-ONLY
DB Size Amazon Aurora
RDS MySQL
30K IOPS (single AZ)
80GB 12,582 585
800GB 9,406 69
CLOUDHARMONY TPC-C
136x
U P TO
FA STER

9. Running with read replicas
Updates per
second Amazon Aurora
RDS MySQL
30K IOPS (single AZ)
1,000 2.62 ms 0 s
2,000 3.42 ms 1 s
5,000 3.94 ms 60 s
10,000 5.38 ms 300 s
SysBench write-only workload
250 tables
500x
UP TO
LOW ER LA G

10. Do fewer IOs
Minimize network packets
Cache prior results
Offload the database engine
DO LESS WORK
Process asynchronously
Reduce latency path
Use lock-free data structures
Batch operations together
BE MORE EFFICIENT
How do we achieve these results?
DATABASES ARE ALL ABOUT I/O
NETWORK-ATTACHED STORAGE IS ALL ABOUT PACKETS/SECOND
HIGH-THROUGHPUT PROCESSING DOES NOT ALLOW CONTEXT SWITCHES

11. IO traffic in RDS MySQL
BINLOG DATA DOUBLE-WRITELOG FRM FILES
T Y P E O F W R IT E
MYSQL WITH STANDBY
Issue write to EBS – EBS issues to mirror, ack when both done
Stage write to standby instance using DRBD
Issue write to EBS on standby instance
IO FLOW
Steps 1, 3, 5 are sequential and synchronous
This amplifies both latency and jitter
Many types of writes for each user operation
Have to write data blocks twice to avoid torn writes
OBSERVATIONS
780K transactions
7,388K I/Os per million txns (excludes mirroring, standby)
Average 7.4 I/Os per transaction
PERFORMANCE
30 minute SysBench write-only workload, 100 GB data set, RDS SingleAZ, 30K
PIOPS
EBS mirrorEBS mirror
AZ 1 AZ 2
Amazon S3
EBS
Amazon Elastic
Block Store (EBS)
Primary
instance
Standby
instance
1
2
3
4
5

12. IO traffic in Aurora (database)
AZ 1 AZ 3
Primary
instance
Amazon S3
AZ 2
Replica
instance
AMAZON AURORA
ASYNC
4/6 QUORUM
DISTRIBUTED
WRITES
BINLOG DATA DOUBLE-WRITELOG FRM FILES
T Y P E O F W R IT E
30 minute SysBench write-only workload, 100 GB data set
IO FLOW
Only write redo log records; all steps asynchronous
No data block writes (checkpoint, cache replacement)
6X more log writes, but 9X less network traffic
Tolerant of network and storage outlier latency
OBSERVATIONS
27,378K transactions 35X MORE
950K I/Os per 1M txns (6X amplification) 7.7X LESS
PERFORMANCE
Boxcar redo log records – fully ordered by LSN
Shuffle to appropriate segments – partially ordered
Boxcar to storage nodes and issue writes

13. IO traffic in Aurora (storage node)
LOG RECORDS
Primary
instance
INCOMING QUEUE
STORAGE NODE
S3 BACKUP
1
2
3
4
5
6
7
8
UPDATE
QUEUE
ACK
HOT
LOG
DATA
BLOCKS
POINT IN TIME
SNAPSHOT
GC
SCRUB
COALESCE
SORT
GROUP
PEER-TO-PEER GOSSIPPeer
storage
nodes
All steps are asynchronous
Only steps 1 and 2 are in foreground latency path
Input queue is 46X less than MySQL (unamplified, per node)
Favor latency-sensitive operations
Use disk space to buffer against spikes in activity
OBSERVATIONS
IO FLOW
① Receive record and add to in-memory queue
② Persist record and ACK
③ Organize records and identify gaps in log
④ Gossip with peers to fill in holes
⑤ Coalesce log records into new data block versions
⑥ Periodically stage log and new block versions to S3
⑦ Periodically garbage collect old versions
⑧ Periodically validate CRC codes on blocks

14. Asynchronous group commits
Read
Write
Commit
Read
Read
T1
Commit (T1)
Commit (T2)
Commit (T3)
LSN 10
LSN 12
LSN 22
LSN 50
LSN 30
LSN 34
LSN 41
LSN 47
LSN 20
LSN 49
Commit (T4)
Commit (T5)
Commit (T6)
Commit (T7)
Commit (T8)
LSN GROWTH
Durable LSN at head-node
COMMIT QUEUE
Pending commits in LSN order
TIME
GROUP
COMMIT
TRANSACTIONS
Read
Write
Commit
Read
Read
T1
Read
Write
Commit
Read
Read
Tn
TRADITIONAL APPROACH AMAZON AURORA
Maintain a buffer of log records to write out to disk
Issue write when buffer full or time out waiting for writes
First writer has latency penalty when write rate is low
Request I/O with first write, fill buffer till write picked up
Individual write durable when 4 of 6 storage nodes ACK
Advance DB durable point up to earliest pending ACK

15. Re-entrant connections multiplexed to active threads
Kernel-space epoll() inserts into latch-free event queue
Dynamically size threads pool
Gracefully handles 5,000+ concurrent client sessions on r3.8xl
Standard MySQL – one thread per connection
Doesn’t scale with connection count
MySQL EE – connections assigned to thread group
Requires careful stall threshold tuning
CLIENTCONNECTION
CLIENTCONNECTION
LATCH FREE
TASK QUEUE
epoll()
MYSQL THREAD MODEL AURORA THREAD MODEL
Adaptive thread pool

16. IO traffic in Aurora (read replica)
PAGE CACHE
UPDATE
Aurora master
30% Read
70% Write
Aurora replica
100% New Reads
Shared Multi-AZ Storage
MySQL master
30% Read
70% Write
MySQL replica
30% New Reads
70% Write
SINGLE-THREADED
BINLOG APPLY
Data volume Data volume
Logical: Ship SQL statements to replica.
Write workload similar on both instances.
Independent storage.
Can result in data drift between master and
replica.
Physical: Ship redo from master to replica.
Replica shares storage. No writes performed.
Cached pages have redo applied.
Advance read view when all commits seen.
MYSQL READ SCALING AMAZON AURORA READ SCALING

17. Improvements over the past few months
Write batch size tuning
Asynchronous send for read/write I/Os
Purge thread performance
Bulk insert performance
BATCH OPERATIONS
Failover time reductions
Malloc reduction
System call reductions
Undo slot caching patterns
Cooperative log apply
OTHER
Binlog and distributed transactions
Lock compression
Read-ahead
CUSTOMER FEEDBACK
Hot row contention
Dictionary statistics
Mini-transaction commit code path
Query cache read/write conflicts
Dictionary system mutex
LOCK CONTENTION

18. Availability
“Performance only matters if your database is up”

19. Storage node availability
Quorum system for read/write; latency tolerant
Peer-to-peer gossip replication to fill in holes
Continuous backup to S3 (designed for 11 9s durability)
Continuous scrubbing of data blocks
Continuous monitoring of nodes and disks for repair
10 GB segments as unit of repair or hotspot rebalance to quickly
rebalance load
Quorum membership changes do not stall writes
AZ 1 AZ 2 AZ 3
Amazon S3

20. Traditional databases
Have to replay logs since the last
checkpoint
Typically 5 minutes between checkpoints
Single-threaded in MySQL; requires a
large number of disk accesses
Amazon Aurora
Underlying storage replays redo records
on demand as part of a disk read
Parallel, distributed, asynchronous
No replay for startup
Checkpointed data Redo log
Crash at T0 requires
a reapplication of the
SQL in the redo log since
last checkpoint
T0 T0
Crash at T0 will result in redo logs being
applied to each segment on demand, in
parallel, asynchronously
Instant crash recovery

21. Survivable caches
We moved the cache out of the
database process
Cache remains warm in the event of a
database restart
Lets you resume fully loaded
operations much faster
Instant crash recovery + survivable
cache = quick and easy recovery from
DB failures
SQL
Transactions
Caching
SQL
Transactions
Caching
SQL
Transactions
Caching
Caching process is outside the DB process
and remains warm across a database restart

22. Faster, more predictable failover
App
runningFailure detection DNS propagation
Recovery Recovery
DB
failure
MYSQL
App
running
Failure detection DNS propagation
Recovery
DB
failure
AURORA WITH MARIADB DRIVER
1 5 - 2 0 s e c
3 - 2 0 s e c

23. ALTER SYSTEM CRASH [{INSTANCE | DISPATCHER | NODE}]
ALTER SYSTEM SIMULATE percent_failure DISK failure_type IN
[DISK index | NODE index] FOR INTERVAL interval
ALTER SYSTEM SIMULATE percent_failure NETWORK failure_type
[TO {ALL | read_replica | availability_zone}] FOR INTERVAL interval
Simulate failures using SQL
To cause the failure of a component at the database node:
To simulate the failure of disks:
To simulate the failure of networking:

24. Amazon Aurora team
work hard. have fun. make history.

25. Thank you!