CloudWatch Metric Guide
DatabaseMemoryUsagePercentageAmazon ElastiCache CloudWatch metric
DatabaseMemoryUsagePercentage reports the percentage of the engine's configured maxmemory currently in use, calculated as used_memory ÷ maxmemory from the Redis/Valkey INFO command. It is Redis/Valkey-specific — Memcached clusters do not emit this metric.
What it measures
About DatabaseMemoryUsagePercentage
DatabaseMemoryUsagePercentage reports the percentage of the engine's configured maxmemory currently in use, calculated as used_memory ÷ maxmemory from the Redis/Valkey INFO command. It is Redis/Valkey-specific — Memcached clusters do not emit this metric.
| Namespace | AWS/ElastiCache |
| Metric name | DatabaseMemoryUsagePercentage |
| Unit | Percent |
| AWS docs | Official Amazon ElastiCache metrics reference |
Why this metric matters
DatabaseMemoryUsagePercentage is the most direct read on how close a Redis/Valkey node is to running out of usable memory, since it's calculated straight from used_memory ÷ maxmemory rather than inferred from host-level RAM figures. Once it reaches 100%, the engine's configured maxmemory-policy takes over: with an eviction policy set, it starts forcibly evicting keys (visible in the Evictions metric); with noeviction set, write commands start failing outright while reads keep working — a much worse failure mode for most applications since it looks like a partial outage rather than a capacity warning.
This metric is Redis/Valkey-only. Memcached clusters have no equivalent maxmemory-percentage metric in CloudWatch — for Memcached, use the host-level FreeableMemory metric (and UnusedMemory, a Memcached-specific calculated metric) as the closest substitutes, keeping in mind AWS's own caveat that Memcached's UnusedMemory should not be read as memory actually available for new data, since engine overhead consumes memory beyond what's used for cached items.
Recommended alarm threshold for DatabaseMemoryUsagePercentage
Recommended threshold
> 90%, sustained for 5 minutes
AWS documentation does not publish a specific percentage threshold for this metric; its closest published guidance is qualitative — that FreeableMemory dropping below ~100MB or SwapUsage exceeding FreeableMemory both indicate memory pressure. The 90% threshold is a Nuberio recommendation intended to alarm before the node reaches its maxmemory ceiling and either evictions or (with noeviction configured) write failures begin.
Is your DatabaseMemoryUsagePercentage alarm already set up correctly?
The free Nuberio Audit scans your CloudWatch setup and flags missing or misconfigured alarms — including DatabaseMemoryUsagePercentage — in 5 minutes.
Common failures that show up in DatabaseMemoryUsagePercentage
When DatabaseMemoryUsagePercentage reaches an alarm threshold, these are the most common root causes — in order of how often Nuberio sees them across customer AWS accounts.
Organic dataset growth as the application caches more keys or larger values over time without a corresponding node size increase
Missing TTLs — keys intended to be short-lived never expire and accumulate indefinitely
Replication and command buffers growing under heavy write or replica-lag conditions, consuming memory beyond the actual dataset
A large one-off data load or migration script writing far more into the cache than the steady-state working set
maxmemory parameter set too low for the node's actual workload after a downsizing or a change in node type
How the Nuberio Audit checks DatabaseMemoryUsagePercentage
The free Audit scans every Amazon ElastiCache resource in your account and checks whether a DatabaseMemoryUsagePercentage 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 DatabaseMemoryUsagePercentage alarms. Free, 5-minute read-only scan.
Related Amazon ElastiCache metrics
DatabaseMemoryUsagePercentage rarely fails in isolation. These metrics tend to correlate — monitor them together for complete Amazon ElastiCache coverage.
FAQ
Frequently asked questions about DatabaseMemoryUsagePercentage
Common questions about setting up CloudWatch alarms for DatabaseMemoryUsagePercentage in Amazon ElastiCache.
What is the recommended CloudWatch alarm threshold for DatabaseMemoryUsagePercentage?+
> 90%, sustained for 5 minutes. AWS documentation does not publish a specific percentage threshold for this metric; its closest published guidance is qualitative — that FreeableMemory dropping below ~100MB or SwapUsage exceeding FreeableMemory both indicate memory pressure. The 90% threshold is a Nuberio recommendation intended to alarm before the node reaches its maxmemory ceiling and either evictions or (with noeviction configured) write failures begin.
Which CloudWatch namespace does DatabaseMemoryUsagePercentage belong to?+
DatabaseMemoryUsagePercentage is published in the AWS/ElastiCache namespace with a unit of Percent. You can find it in the CloudWatch console under "Metrics" → "AWS/ElastiCache". See the Amazon ElastiCache CloudWatch metrics reference in the AWS documentation.
Does Nuberio automatically create CloudWatch alarms for DatabaseMemoryUsagePercentage?+
No — the free Nuberio Audit does not create alarms for you. It scans your CloudWatch setup and tells you which Amazon ElastiCache resources are missing a DatabaseMemoryUsagePercentage alarm, then gives you the exact CLI command to create it yourself.
Can I use Nuberio without already having a DatabaseMemoryUsagePercentage alarm set up?+
Yes. The free Audit works whether or not you have any DatabaseMemoryUsagePercentage 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, and DynamoDB. To find which Amazon ElastiCache alarms your account is missing — including DatabaseMemoryUsagePercentage — run the free CloudWatch alarm audit. The scan takes under 5 minutes and requires no account.