CloudWatch Metric Guide
EBSIOBalance%Amazon EC2 CloudWatch metric
EBSIOBalance% reports the percentage of I/O credits remaining in an instance's EBS burst bucket. It is available only for some *.4xlarge instance sizes and smaller that can burst to maximum EBS performance for up to 30 minutes at least once every 24 hours — not every instance size reports this metric.
What it measures
About EBSIOBalance%
EBSIOBalance% reports the percentage of I/O credits remaining in an instance's EBS burst bucket. It is available only for some *.4xlarge instance sizes and smaller that can burst to maximum EBS performance for up to 30 minutes at least once every 24 hours — not every instance size reports this metric.
| Namespace | AWS/EC2 |
| Metric name | EBSIOBalance% |
| Unit | Percent |
| AWS docs | Official Amazon EC2 metrics reference |
Why this metric matters
EBSIOBalance% is an instance-level burst-credit gauge, not a volume-level one — it measures how much I/O headroom the instance itself has left, separate from any per-volume BurstBalance on the attached EBS volumes. Smaller instance sizes (*.4xlarge and below, per AWS documentation) get a baseline EBS IOPS rate plus the ability to burst above it for up to 30 minutes at least once every 24 hours; EBSIOBalance% tracks how much of that burst allowance remains.
When the balance depletes to 0%, the instance is hard-capped to its baseline EBS IOPS rate — every read/write op above that rate queues, and application-level disk latency spikes even though the attached EBS volumes themselves may have plenty of their own BurstBalance or provisioned IOPS left. This is easy to misdiagnose as a volume problem (checking BurstBalance on the volume shows it's fine) when the real constraint is the instance's own burst bucket. AWS notes the Sum statistic doesn't apply to this metric — only Minimum and Maximum are meaningful.
Recommended alarm threshold for EBSIOBalance%
Recommended threshold
Minimum < 20% sustained
AWS doesn't publish a universal alarm threshold for EBSIOBalance% — it recommends using the metric to right-size instances (consistently low balance is a sizing signal, a balance that never drops below 100% is a downsizing candidate). The 20% floor (Nuberio recommendation) gives enough runway to act before the instance is hard-capped to baseline IOPS. Use the Minimum statistic, since Sum isn't applicable to this metric per AWS documentation.
Is your EBSIOBalance% alarm already set up correctly?
The free Nuberio Audit scans your CloudWatch setup and flags missing or misconfigured alarms — including EBSIOBalance% — in 5 minutes.
Common failures that show up in EBSIOBalance%
When EBSIOBalance% reaches an alarm threshold, these are the most common root causes — in order of how often Nuberio sees them across customer AWS accounts.
Instance undersized for its I/O workload — a *.4xlarge or smaller instance is running a sustained-high-IOPS workload that exceeds its baseline rate for longer than the 30-minute burst window allows
Misdiagnosed as a volume issue — the attached EBS volume's own BurstBalance or provisioned IOPS looks healthy, masking that the instance-level burst bucket (not the volume) is actually depleted
Multiple high-I/O volumes attached to one small instance — several EBS volumes on the same instance compete for the same shared instance-level burst bucket, depleting it faster than a single-volume workload would
No burst-window recovery time — a workload that runs I/O-intensive jobs back-to-back without idle periods never lets the burst bucket refill before the next burst is needed
How the Nuberio Audit checks EBSIOBalance%
The free Audit scans every Amazon EC2 resource in your account and checks whether a EBSIOBalance% alarm exists, whether its threshold and evaluation period are configured sensibly, and flags it if it's missing entirely. Every finding comes with the exact CLI command to fix it — read-only access, no credit card, results in about 5 minutes.
Nuberio Audit
Scans your CloudWatch setup for missing or misconfigured EBSIOBalance% alarms. Free, 5-minute read-only scan.
Related Amazon EC2 metrics
EBSIOBalance% rarely fails in isolation. These metrics tend to correlate — monitor them together for complete Amazon EC2 coverage.
FAQ
Frequently asked questions about EBSIOBalance%
Common questions about setting up CloudWatch alarms for EBSIOBalance% in Amazon EC2.
What is the recommended CloudWatch alarm threshold for EBSIOBalance%?+
Minimum < 20% sustained. AWS doesn't publish a universal alarm threshold for EBSIOBalance% — it recommends using the metric to right-size instances (consistently low balance is a sizing signal, a balance that never drops below 100% is a downsizing candidate). The 20% floor (Nuberio recommendation) gives enough runway to act before the instance is hard-capped to baseline IOPS. Use the Minimum statistic, since Sum isn't applicable to this metric per AWS documentation.
Which CloudWatch namespace does EBSIOBalance% belong to?+
EBSIOBalance% is published in the AWS/EC2 namespace with a unit of Percent. You can find it in the CloudWatch console under "Metrics" → "AWS/EC2". See the Amazon EC2 CloudWatch metrics reference in the AWS documentation.
Does Nuberio automatically create CloudWatch alarms for EBSIOBalance%?+
No — the free Nuberio Audit does not create alarms for you. It scans your CloudWatch setup and tells you which Amazon EC2 resources are missing a EBSIOBalance% alarm, then gives you the exact CLI command to create it yourself.
Can I use Nuberio without already having a EBSIOBalance% alarm set up?+
Yes. The free Audit works whether or not you have any EBSIOBalance% alarm configured — it reads the resource directly from CloudWatch and tells you which resources need one, plus the copy-paste AWS CLI command to create it.
This page is part of the CloudWatch metric guide — thresholds and debugging guidance for every metric across RDS, Lambda, ECS, ALB, EC2, DynamoDB, SQS, API Gateway, S3, CloudFront, ElastiCache, and EKS. To find which Amazon EC2 alarms your account is missing — including EBSIOBalance% — run the free CloudWatch alarm audit. The scan takes under 5 minutes and requires no account.