Scalability and High Availability in the World of Shared Hosting
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Transcript of Scalability and High Availability in the World of Shared Hosting
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Scalability and high availability
in the world of shared hosting
Igor Seletskiy,
CEO, CloudLinux
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Is the topic still relevant?
Cloud vs Cluster
SAN vs NAS
Single server CP vs multi-server CP
VPS vs Shared Hosting
Scaling a site beyond single server
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Cloud & Shared Hosting
Easy migrations
SAN ability to move to new hardware instantly
Grow your servers as needed
Out of the box CP (cPanel, Plesk)
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Cloud Pitfalls
SAN
IO performance
Single point of failure
FSCK is still here
Hypervisor issues
Hypervisor System Failure Risks
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Shared Hosting and Clustering
Load Balancer
NFS Shared Storage DBMail
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Clustering - Benefits
Fault tolerance
No single point of failure
Scalability
Simplified backups
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Clustering - Pitfalls
Complexity
Software failures
Configuration issues
Human Errors
Monitoring
Shared storage
No good control panel
Expensive
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Shared Storage NFS is slow
Local Storage
Open
Read
.
Read
Close
Shared Storage
Local NFS server
Open
Read Open
Read
Close
Read Open
Read
Close
Close
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Shared Storage
No alternatives to NFS
GlusterFS, Lustre, etc
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Sessions
Where to store?
Memcache
Disk
Session affinity
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Single server CP vs cluster CP
Cluster CP are difficult to do & maintain
Home made CPs tend to get outdated
GoDaddy switched to cPanel
cPanel & Plesk have more features than any
clustered/home made CP
No 3rd party extensions
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Scalability Why VPS?
Site using too much resources
Site needs specific software
VPS cannot solve scaling beyond single server
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CloudLinux HA platform
Cluster
No NFS (no shared storage)
Fully compatible with cPanel
On Demand high availability
Site scalability beyond single server
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General Arch
LB cPanel Servers Web Appliances C&C server
INTERNET
C&C
Web Appliances Web Appliances Web Appliances cPanel cPanel
NGINX NGINX
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cPanel
Acc 1
Acc 2
Acc 3
Acc 4
WA WA
cPanel Server
1:1 NAT
Enable account for high availability
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Web Appliance
Hold sites from multiple cPanel servers
Automatically replicate sites if needed
NGINX
C&C
WA WA
C2A1 C1A1
C1A2 C1A2
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Web Appliance
weakly shared file system: Inotify & lsyncd
CageFS
PHP Selector / Python / Ruby
Sessions
MySQL (socat/smart library)
Crontab -> cPanel
Sendmail -> cPanel
Other external commands -> cPanel
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Future Shared File System
Mostly reads
Writes are rare
Locks are rare, can be costly
Locks can be costly
Resolve conflicts in favor of any
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Other Components
MySQL
Mail
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Future
What we call today Shared hosting can grow into a platform used to serve some of the most popular internet
resources
There should be no reason for a website
owner to move to VPS
If you want to learn more, talk to as at booth D20
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