💾 Amazon EBS Volume Types
EBS gives EC2 instances persistent block storage — like a virtual hard drive. AWS offers six volume types across three categories, balancing performance, cost, and reliability.
⚡ General Purpose SSD — gp2 & gp3
The default choice for most workloads: boot volumes, web servers, dev/test, virtual desktops.
gp3 (recommended) — storage, IOPS, and throughput are configured independently. Scale one without touching the others.
gp2 (previous gen) — storage size and IOPS are linked; bigger volume = more IOPS automatically.
💡 Exam tip: gp3 = independent config. gp2 = size and performance tied together.
🚀 Provisioned IOPS SSD — io1 & io2 Block Express
Built for workloads that can't tolerate inconsistent performance: enterprise databases, financial systems, mission-critical apps.
Extremely high IOPS, very low latency, high reliability
io2 Block Express = highest performance, larger max size than io1
Only io1/io2 support EBS Multi-Attach
💡 Exam tip: "High-performance database" or "mission-critical" in a question → think io1/io2.
🗄️ HDD Volumes — st1 & sc1
Optimized for throughput or cost, not latency.
📊 st1 (Throughput Optimized HDD) — big sequential data: analytics, log processing, data warehousing.
🗃️ sc1 (Cold HDD) — cheapest EBS option, for rarely-accessed archives and backups.
📏 Key Performance Metrics
📦 Capacity — total volume size
⚡ IOPS — read/write ops per second
🚀 Throughput — data transferred per second
⚠️ Boot Volume Support
✅ Can boot an instance: gp2, gp3, io1, io2 🚫 Cannot: st1, sc1
🧠 Comparison Table — SSD Volumes
Feature | gp3 | gp2 | io2 Block Express | io1 |
|---|---|---|---|---|
Category | General Purpose | General Purpose | Provisioned IOPS | Provisioned IOPS |
Durability | 99.8–99.9% | 99.8–99.9% | 99.999% | 99.8–99.9% |
Size | 1 GiB–16 TiB | 1 GiB–16 TiB | 4 GiB–64 TiB | 4 GiB–16 TiB |
Max IOPS | 16,000 | 16,000 | 256,000 | 64,000 |
Max Throughput | 1,000 MiB/s | 250 MiB/s | 4,000 MiB/s | 1,000 MiB/s |
Multi-Attach | ❌ | ❌ | ✅ | ✅ |
Boot Volume | ✅ | ✅ | ✅ | ✅ |
🧠 Comparison Table — HDD Volumes
Feature | st1 | sc1 |
|---|---|---|
Use case | Big data, log processing | Archives, cold storage |
Size | 125 GiB–16 TiB | 125 GiB–16 TiB |
Max IOPS | 500 | 250 |
Max Throughput | 500 MiB/s | 250 MiB/s |
Boot Volume | ❌ | ❌ |
🎯 Exam Cheat Sheet
gp3 → balanced, independent config, default recommendation
gp2 → older, size-linked performance
io1/io2 → high-performance, mission-critical, Multi-Attach capable
st1 → throughput-heavy sequential workloads
sc1 → cheapest, infrequent access
Boot-capable: gp2, gp3, io1, io2 only