As a website or application grows in popularity, it will inevitably reach a point where it needs to scale beyond a single server. The traffic load becomes too great for one machine to handle, performance slows down, and outages occur more frequently. This is when scaling your web hosting infrastructure becomes necessary.
While scaling provides many benefits, it also poses some unique challenges. The solutions are not always straightforward and require careful planning and monitoring. In this guide, we will explore the most common challenges encountered when scaling web hosting and proven methods to address them.
Challenge 1: Achieving High Availability
One of the primary goals when scaling is minimizing downtime. As you add more servers, there are more potential points of failure. If one server goes down, you want the application to continue running uninterrupted on the remaining servers.
There are two common solutions for building highly available infrastructure:
Load Balancers – A load balancer sits in front of your servers and distributes requests between them. If one server fails, the load balancer directs traffic to the remaining online servers. This provides failover with no interruption to users. Load balancers at the database tier can also route read/write requests appropriately.
Redundancy – Keeping redundant servers that can quickly take over if a primary server fails is key. This might involve having hot standby servers waiting to spring into action or running multiple data centers in different regions. With proper redundancy, users won’t notice if a server goes down.
Challenge 2: Coping with Increasing Storage Needs
Data storage needs tend to grow rapidly along with website traffic. This data includes user files, databases, logs, etc. At a certain point, storing and managing all this data on individual servers is no longer feasible.
Two common storage scaling solutions include:
Network Attached Storage (NAS) – A dedicated NAS appliance provides expanded storage that can be accessed by multiple servers via the network. This makes it easy to add storage capacity without adding servers. NAS systems also include data redundancy features like RAID and snapshots.
Cloud Storage – Services like Amazon S3, Google Cloud Storage and Azure Blob Storage provide infinitely scalable cloud storage. Web servers can access files in cloud storage via API requests. Cloud storage also handles redundancy and failover behind the scenes.
Challenge 3: Handling Increasing Database Load
The database tier is often a bottleneck when scaling. Standard databases like MySQL and Postgres only scale vertically on a single server. Eventually the write and read load becomes more than a single database server can handle.
Common ways to scale the database tier include:
Database Replication – Setting up master-slave database replication allows read queries to be distributed among multiple slave servers. The master handles all writes. This removes query load from the primary database.
Database Clustering – Database clustering software like MySQL Cluster and PostgresXL allow the database to be distributed across multiple nodes. This permits horizontal scaling of both reads and writes.
Caching – Implementing a caching layer like Memcached or Redis can take load off the database by caching frequent queries and data. This reduces database load dramatically.
Challenge 4: Scaling Application Servers
Most web applications utilize an application server like Tomcat for Java apps or Passenger for Ruby on Rails. Too much load will bog down and crash an app server.
Application servers can be scaled horizontally by adding more servers and load balancing requests between them. Things to consider:
Session management – Sessions need to be shared between app servers, often by storing them in a shared cache like Memcached or Redis.
File uploads -Uploaded files should be stored on a shared file system or cloud storage that all app servers can access.
Application configurations – Configuration files may need to be centralized so changes apply across all servers.
Logging – Centralized logging allows logs from multiple servers to be easily analyzed in one place.
Challenge 5: Scaling the Content Delivery Network
A content delivery network (CDN) like Cloudflare or Amazon CloudFront improves performance by caching static assets across global edge servers. This reduces load on the origin web servers.
As traffic grows, CDN bandwidth and storage needs to scale up. Most CDNs handle this seamlessly by adding more edge servers around the world. Some things to watch out for:
Cache invalidation – When content is updated, the CDN cache needs to be cleared so visitors get the latest files. Cache invalidation can become complex on large sites.
Custom origins – Scaling up custom origin web servers is necessary to handle increased asset requests from the CDN servers as your user base grows.
Challenge 6: Maintaining Security
With a larger and more complex infrastructure, new potential attack vectors open up. Steps to keep security tight when scaling include:
Access management – Limit administrative access to servers and infrastructure. Use role-based access control and multi-factor authentication.
Network security – Use VPCs, subnets, firewall rules and internal load balancers to restrict unneeded network access between components.
Encryption -Encrypt data in transit and at rest. Use HTTPS load balancers and enable encryption capabilities of databases and cloud services.
Intrusion detection – Implement host and network-based IDS/IPS systems to detect malicious activity across the infrastructure.
Penetration testing – Conduct regular penetration tests to find and address vulnerabilities before they are exploited.
Challenge 7: Monitoring Performance
Monitoring becomes more difficult but also more critical with large, complex infrastructure. Things to watch out for:
Resource utilization – Monitor CPU, memory, disk and network usage across all servers to watch for constraints and bottlenecks.
Error rates – Track failed requests, error codes and exceptions that impact the user experience.
Uptime and availability – Get alerts if any component experiences downtime or high error rates so issues can be addressed rapidly.
End user experience – Employ synthetic monitoring to simulate user transactions and measure real-world response times and availability from multiple geographic regions.
Challenge 8: Automating Maintenance
With larger infrastructure, manually running maintenance tasks like system updates, certificate renewals and configuration changes becomes tedious and difficult. Automation is key.
Automated configuration management tools like Ansible, Chef and Puppet allow you to push configuration changes to any number of servers.
Container orchestration platforms like Kubernetes allow complex infrastructure to be managed, monitored and automatically updated.
Infrastructure as code tools like Terraform and CloudFormation enable infrastructure to be codified and deployed automatically.
Challenge 9: Optimizing Cost Efficiency
A key benefit of scaling infrastructure is the ability to better optimize costs based on demand. However, cost efficiency requires ongoing attention and planning.
Analyze usage over time. Use cloud auto-scaling features and adjust reserved instance purchases to minimize waste.
Take advantage of cloud savings like reserved instances, spot instances and committed use discounts where possible.
Right size servers. Monitor usage and resize instances to fit needs. Use tools like AWS Trusted Advisor to optimize spending.
Allocate costs appropriately by tagging resources and making use of detailed cloud billing options.
Leverage third party reserved instance marketplaces to resell unwanted reserved capacity.
Challenge 10: Planning Infrastructure Growth
Even with systems designed for automated scaling, planning future infrastructure growth is important. You want to maximize performance and minimize costs.
Monitor growth trends and forecasts usage patterns – this will guide expansion plans.
Benchmark systems under realistic loads to understand scaling limits.
Review cloud architecture regularly and improvements to take advantage of new services and features.
Plan ahead for large events like new product launches that may require capacity spikes.
Maintain system documentation and utilize infrastructure as code tools for standardized and repeatable deployments.
Scaling web hosting and infrastructure brings many benefits but also new challenges to overcome. Planning ahead and utilizing the range of solutions covered in this guide will enable you to scale successfully. The key is taking a holistic approach – monitoring overall system performance, automating tasks, optimizing costs and planning for future growth. With robust architecture and processes in place, your systems will be able to fluidly scale up to handle whatever demands your increasingly popular applications require.