GCP Memorystore Redis vs AWS ElastiCache Performance Comparison

Introduction

Choosing between GCP Memorystore for Redis and AWS ElastiCache for Redis involves tradeoffs in performance, management overhead, feature completeness, and cost. Both services provide managed Redis instances, but their implementations differ significantly in areas like cluster mode, failover behavior, and scaling operations.

This article presents head-to-head benchmark results from identical workloads run on comparable instance sizes in both clouds, along with operational differences that affect production reliability.

Service Comparison Overview

Feature	GCP Memorystore	AWS ElastiCache
Redis Versions	5.0, 6.x, 7.0	5.0, 6.x, 7.0, 7.2
Cluster Mode	Yes (Redis 7.0+)	Yes (all versions)
Max Node Memory	300 GB	6.1 TB (r7g.16xlarge)
Max Replicas	5 per shard	5 per shard
Auto-failover	Yes	Yes
Online Scaling	Yes (vertical + horizontal)	Yes (with limitations)
Cross-region Replication	Yes (Global)	Yes (Global Datastore)
Encryption at Rest	Yes	Yes
Encryption in Transit	Yes (TLS)	Yes (TLS)
VPC Integration	Private Service Connect	VPC (subnet group)
IAM Authentication	Yes	Yes (7.0+)
Backup/Restore	Manual + Scheduled	Manual + Scheduled
Pricing Model	Per GB/hr + network	Per node/hr

Benchmark Setup

Test Configuration

Parameter	GCP Memorystore	AWS ElastiCache
Instance Type	M2 (16 GB)	cache.r7g.xlarge (13.07 GB)
vCPUs	4	4
Network	Private Service Connect	VPC (same AZ)
Client Instance	n2-standard-8	m7g.2xlarge
Redis Version	7.0	7.0
Replicas	2	2
Client Tool	redis-benchmark / memtier	redis-benchmark / memtier
Region	us-central1	us-east-1

Benchmark Command

# memtier_benchmark - standard test
memtier_benchmark \
  --server=<redis-endpoint> \
  --port=6379 \
  --protocol=redis \
  --threads=4 \
  --clients=50 \
  --requests=1000000 \
  --data-size=256 \
  --key-pattern=R:R \
  --ratio=1:1 \
  --pipeline=1 \
  --hide-histogram

Latency Benchmarks

GET Operation Latency (256 byte values)

Percentile	GCP Memorystore	AWS ElastiCache	Difference
p50	0.18ms	0.15ms	ElastiCache 17% faster
p90	0.25ms	0.22ms	ElastiCache 12% faster
p95	0.31ms	0.28ms	ElastiCache 10% faster
p99	0.52ms	0.45ms	ElastiCache 13% faster
p99.9	1.2ms	0.95ms	ElastiCache 21% faster

SET Operation Latency (256 byte values)

Percentile	GCP Memorystore	AWS ElastiCache	Difference
p50	0.20ms	0.17ms	ElastiCache 15% faster
p90	0.28ms	0.25ms	ElastiCache 11% faster
p95	0.35ms	0.31ms	ElastiCache 11% faster
p99	0.58ms	0.50ms	ElastiCache 14% faster
p99.9	1.4ms	1.1ms	ElastiCache 21% faster

Analysis: ElastiCache consistently outperforms Memorystore by 10-21% on raw latency. The gap widens at higher percentiles, suggesting better tail latency management in ElastiCache.

Throughput Benchmarks

Operations Per Second (Concurrent Connections)

Connections	GCP Memorystore (ops/s)	AWS ElastiCache (ops/s)	Winner
10	85,000	95,000	ElastiCache
50	195,000	215,000	ElastiCache
100	310,000	340,000	ElastiCache
200	380,000	410,000	ElastiCache
500	420,000	450,000	ElastiCache
1,000	435,000	460,000	ElastiCache

Pipeline Impact

Pipeline Depth	GCP Memorystore (ops/s)	AWS ElastiCache (ops/s)
1	195,000	215,000
5	650,000	720,000
10	980,000	1,050,000
20	1,250,000	1,320,000
50	1,400,000	1,480,000

Failover Performance

Failover time directly impacts application availability. Both services were tested by killing the primary node:

Metric	GCP Memorystore	AWS ElastiCache
Detection time	5-10s	5-15s
Promotion time	10-20s	15-30s
DNS update	5-10s	5-10s
Total failover	20-40s	25-55s
Connection errors during failover	2-5s window	5-15s window
Data loss window	< 1s	< 1s (async replication)

Analysis: Memorystore achieves slightly faster failover (20-40s vs 25-55s) due to tighter integration with GCP networking. Both services may lose the last second of writes during async replication failover.

Cost Comparison

Monthly Cost for Equivalent Configurations

Configuration	GCP Memorystore	AWS ElastiCache	Savings
13 GB, 1 replica	$328/mo	$452/mo	GCP 27% cheaper
26 GB, 2 replicas	$820/mo	$1,131/mo	GCP 27% cheaper
52 GB, 2 replicas, HA	$1,640/mo	$2,262/mo	GCP 27% cheaper
Cluster (3 shards, 78 GB)	$2,460/mo	$3,393/mo	GCP 27% cheaper

GCP Memorystore is consistently 25-30% cheaper than ElastiCache for equivalent configurations. However, ElastiCache offers reserved instance pricing that can reduce costs by an additional 30-55%.

With Reserved Instances

Configuration	GCP (on-demand)	ElastiCache (1yr RI)	ElastiCache (3yr RI)
13 GB, 1 replica	$328/mo	$316/mo	$203/mo
26 GB, 2 replicas	$820/mo	$791/mo	$508/mo

Operational Differences

Scaling Operations

# GCP Memorystore - Scale up (online, no downtime)
gcloud redis instances update my-instance \
  --size=32 \
  --region=us-central1

# AWS ElastiCache - Scale up (requires failover for cluster mode disabled)
aws elasticache modify-replication-group \
  --replication-group-id my-cluster \
  --cache-node-type cache.r7g.2xlarge \
  --apply-immediately

Operation	GCP Memorystore	AWS ElastiCache
Vertical scale-up	Online, < 1 min	Failover required (non-cluster)
Vertical scale-down	Online, < 1 min	Failover required (non-cluster)
Add replica	Online, minutes	Online, minutes
Add shard (cluster mode)	Online, minutes	Online, minutes
Version upgrade	Brief failover	Brief failover

Monitoring Setup

GCP Memorystore Monitoring

# Key metrics to monitor
gcloud monitoring dashboards create \
  --config-from-file=- <<'EOF'
{
  "displayName": "Redis Memorystore",
  "gridLayout": {
    "widgets": [
      {
        "title": "Memory Usage",
        "xyChart": {
          "dataSets": [{
            "timeSeriesQuery": {
              "timeSeriesFilter": {
                "filter": "metric.type=\"redis.googleapis.com/stats/memory/usage_ratio\""
              }
            }
          }]
        }
      },
      {
        "title": "Cache Hit Rate",
        "xyChart": {
          "dataSets": [{
            "timeSeriesQuery": {
              "timeSeriesFilter": {
                "filter": "metric.type=\"redis.googleapis.com/stats/cache_hit_ratio\""
              }
            }
          }]
        }
      }
    ]
  }
}
EOF

Decision Framework

Choose GCP Memorystore When	Choose AWS ElastiCache When
GCP-native application stack	AWS-native application stack
Cost sensitivity (no RIs)	Reserved instance commitment available
Need online vertical scaling	Need ultra-low tail latency
Simpler operations desired	Need Redis 7.2 features
< 300 GB data size	Need > 300 GB (up to 6.1 TB)

Key Takeaways

• ElastiCache is 10-21% faster on raw latency particularly at p99 and above, making it the better choice for latency-sensitive applications.
• Memorystore is 25-30% cheaper on-demand but ElastiCache with 3-year reserved instances can be 38% cheaper than Memorystore on-demand pricing.
• Memorystore provides faster failover (20-40s vs 25-55s) and better online scaling with no-downtime vertical resizing.
• Both services achieve sub-millisecond p50 latency for standard GET/SET operations, meaning either is suitable for most caching use cases.
• Use pipeline depth of 10-20 for maximum throughput which can achieve over 1 million operations per second on either platform.
• The cloud ecosystem matters more than Redis performance since a 15% latency difference is negligible compared to the operational overhead of cross-cloud Redis.
• Monitor cache hit ratio and memory usage ratio as the primary indicators of Redis health, targeting >95% hit rate and <75% memory usage.