Global Varnish Cluster with GeoDNS

Improving Site Response Time Part 2: Global Varnish Cluster with GeoDNSKim Stefan Lindholm 1 18.2.2012

SETUPSame components as before with following additions/modiﬁcations:• Varnish Server: Amazon EC2 Micro Instance (613 MB)• Varnish Monitoring: New Relic, Munin, RevealCloud• Edge Locations: Tokyo, California, Ireland• GeoDNS: EdgeDirector DNS and newly added Google Analytics + New Relic code may slightly affect load times 2

Front-end optimization can speed up a website but doesn’t tackle networklatency. Content must be brought closer to visitors. 3

LOAD TIME, BEFORE Target Speed (1.5 Mbps connection) Average: <3.5s18 s Worst Case: <5s14 s Worst Case 9s Average 5s Los Angeles São Paulo Stockholm Shanghai Sydney ✘ ✘ ✘ ✘ ✘ 4

Solution: Set up remote Varnish caches and direct visitors to the nearest one with GeoDNS 5

Varnish serves ﬁles that it has previously cached (in its assigned geographic area) Varnish fetches uncached or expired content through Incapsula, never directly from website Incapsula fetches uncached content from origin server(s) If edge server is unresponsive, DNS failover redirects to Incapsula or another Varnish Website Varnish VarnishVarnish Incapsula 6

LOCAL VS. REMOTE VARNISH• Why would we place a Varnish box in the same region as the website? • Severalcloud application platforms (CloudControl, Heroku, etc.) have Varnish running locally but only default configuration is supported • Incapsula sets cookies but Varnish doesnt serve cached results to sessions with cookies ➔ limited benefits with default settings • We’dlike to see cache hit rates of up to 99.9 % so by manually configuring Varnish we ensure that it actually does its job 7

LOAD TIME, AFTER Target Speed (1.5 Mbps connection) Dotted line denotes load time before Average: <3.5s18 s Worst Case: <5s14 s Worst Case 9s Average 5s Los Angeles São Paulo Stockholm Shanghai Sydney ✔ ✔ ✔ ✔ ✔ 8

http://royal.pingdom.com/2010/11/12/real-connection-speeds-for-internet-users-across-the-world/“The average connection speed forInternet users worldwide, not just amongthese 50 countries, but all countries, isan average of 1.8 Mbit/s”We’ll use 1.5 Mbit/s and 5.0 Mbit/sconnections in tests that follow 9

TARGET SPEED, AVERAGE 1.5 Mbps <3.5s 5.0 Mbps <2.5s 10

1.5 Mbps AVERAGE, BEFORE CloudFront 4.0 s 3.5 s 2.5 s 3.8 s 4.4 s 2.9 s 2.7 s 3.5 s 6.0 s 4.9 s 3.7 s 4.9 s 5.8 s <3.5s <3.5s <3.5s5 measurements, >20 min intervals 11 DNS Provider: DNS Made Easy

1.5 Mbps AVERAGE, BEFORE Akamai 3.6 s 3.3 s 2.1 s 4.5 s 5.0 s 3.1 s 2.7 s 3.7 s 6.2 s 4.8 s 4.9 s 4.0 s 4.8 s <3.5s <3.5s <3.5s5 measurements, >20 min intervals 12 DNS Provider: DNS Made Easy

1.5 Mbps CDN COMPARISON CloudFront Akamai - 0.4 s - 0.2 s - 0.4 s - 0.7 s - 0.6 s - 0.2 s 0.0 s - 0.2 s - 0.2 s - 0.1 s - 1.2 s - 0.9 s - 1.0 s We’ll be using CloudFront for subsequent tests5 measurements, >20 min intervals 13 DNS Provider: DNS Made Easy

1.5 Mbps AVERAGE, AFTER CloudFront 1.8 s 3.4 s 1.9 s 1.5 s 3.0 s 2.3 s 1.8 s 2.1 s 2.8 s 3.1 s 2.6 s 2.8 s 2.5 s <3.5s <3.5s <3.5s5 measurements, >20 min intervals 14 DNS Provider: EdgeDirector

5.0 Mbps AVERAGE, AFTER CloudFront 1.2 s 2.9 s 1.5 s 2.0 s 2.4 s 1.8 s 1.1 s 1.7 s 2.2 s 2.6 s 1.9 s 2.1 s 2.0 s <2.5s <2.5s <2.5s5 measurements, >20 min intervals 15 DNS Provider: EdgeDirector

TARGET SPEED, WORST CASE 1.5 Mbps <5.0s 5.0 Mbps <4.0s 16

1.5 Mbps WORST CASE, BEFORE CloudFront 4.4 s 4.2 s 3.2 s 6.0 s 6.5 s 3.1 s 3.2 s 4.3 s 8.0 s 5.3 s 4.5 s 10.4 s 9.8 s <5.0s <5.0s <5.0s5 measurements, >20 min intervals 17 DNS Provider: DNS Made Easy

1.5 Mbps WORST CASE, AFTER CloudFront 1.9 s 4.0 s 2.2 s 1.6 s 4.6 s 2.3 s 2.1 s 2.7 s 3.6 s 3.6 s 3.2 s 3.9 s 2.8 s <5.0s <5.0s <5.0s5 measurements, >20 min intervals 18 DNS Provider: EdgeDirector

5.0 Mbps WORST CASE, AFTER CloudFront 1.4 s 3.0 s 1.7 s 3.9 s 3.2 s 1.9 s 1.2 s 2.2 s 2.8 s 2.9 s 2.2 s 2.2 s 2.2 s <4.0s <4.0s <4.0s5 measurements, >20 min intervals 19 DNS Provider: EdgeDirector

CDN doesn’t guarantee optimaldelivery locations. Where were assets actually served from? 20

AKAMAI LOCATIONS Files were loaded from 2 continentsCloudFront seems to load all ﬁles from Seattle which is just a simple geo-IP lookup issue 21

How much does a minimal Varnish cluster cost? 22

SERVERS VPS / Cloud Server Locations RAM Storage Price/month Linode 512 US, UK, Japan 512 MB 20 GB $19.95 Hetzner VQ 7 Germany 512 MB 20 GB €7.90 Zerigo Linux Denver, CO 512 MB 24 GB $19 Amazon EC2 micro US, EU, Asia, Brazil 613 MB 20 GB (EBS) $16.7 / $20.7NB 1: Varnish should run on a 64-bit serverNB 2: Amazon prices are for California and Tokyo, reserved, heavy utilization, 30 GB trafﬁc 23

GEODNS Zerigo DNS DNS Made Easy DNS.com EdgeDirector Pro 4 Business + GTD Basic / Pro + Monitoring Monthly Queries 4 million 10 million 5 / 15 million Unlimited $1.5 / monitor + Monthly Price $20 $60 $34.95 $15 / M queries + DNS Failover X Included (3) X Included (1) + DNSSEC X X Included X + Vanity Name Included Included $44.95 X ServersNB: For a small website, EdgeDirector can cost less than $3/month 24

Without DNS Failover2 x Linode server + Zerigo DNS (1 M queries)= 720 USD (~550 EUR) per yearWith DNS Failover2 x Linode server + EdgeDirector (1 M queries)= 690 USD (~530 EUR) per year 25 Rates in February 2012

LEARNINGS• Varnishmade a real improvement in response time (up to 7 sec) and as it now handles more than 99 % of requests, a website with few DB write operations performs ﬁne even on shared cloud hosting• Varnish boxes don’t scale up automatically but as DNS failover bypasses failed edge servers, this doesn’t seem like a problem• GeoDNS isn’t always necessary for accelerating a website: even one Varnish serving all requests globally will signiﬁcantly improve performance 26

LEARNINGS• Amazon micro instance isn’t suitable for production use due to high CPU steal• Setting up Varnish is pretty straightforward, see Part 3 for an example conﬁguration on Amazon EC2 27

RESOURCES• Cloud & Virtual Private Servers (VPS) • Linode, http://www.linode.com/ • Hetzner, http://www.hetzner.de/hosting/produktmatrix_vserver/vserver-produktmatrix • Zerigo, http://www.zerigo.com/vps-servers • Amazon EC2, http://aws.amazon.com/ec2/• GeoDNS / Global Server Load Balancing (GSLB) • http://www.zerigo.com/docs/managed-dns/setting_up_geodns • http://help.dnsmadeeasy.com/gtd/conﬁgure-gtd-with-dns-failover/ • http://dns.com/Help/#conﬁgure • http://edgedirector.com/how/both.htm 28

Global Varnish Cluster with GeoDNS

by Kim Stefan Lindholm on Feb 19, 2012

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