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Zorluk: ZorImplement Azure Cache for Redis Configuration and Data Patterns

You maintain a Premium tier Azure Cache for Redis instance that supports a high-throughput data processing application. The application frequently writes, updates, and deletes large, complex serialized objects. During peak loads, the hosting virtual machines experience out-of-memory (OOM) crashes, even though the Used Memory metric reported by the cache remains below the allocated maxmemory limit. You observe that the memory fragmentation ratio is high. You need to configure the cache to prevent these VM-level OOM crashes by forcing Redis to perform evictions or fail writes before physical memory is exhausted. Which configuration setting should you adjust?

  1. Increase the maxfragmentationmemory-reserved configuration setting.Cevap
  2. B
    Increase the maxmemory-reserved configuration setting.
  3. C
    Set the maxmemory-policy configuration setting to noeviction.
  4. D
    Enable RDB data persistence and set the backup frequency to maximum.

Cevap

Increase the maxfragmentationmemory-reserved configuration setting.
Increasing the maxfragmentationmemory-reserved configuration setting reserves a specified amount of physical memory to accommodate fragmentation. When the physical memory usage exceeds the allowed threshold minus this reserved value, Redis starts evicting keys or failing writes according to the maxmemory-policy. This prevents the hosting virtual machine's operating system from running out of physical memory and crashing the Redis process.

Adım Adım Çözüm

1
Analyze the crash symptoms and metrics.
The VM crashes due to system-level OOM, but the Used Memory metric is below the maxmemory limit, indicating that memory fragmentation is the primary driver of physical memory exhaustion.
Used Memory measures logical memory allocated for data keys, but doesn't fully represent the actual physical memory footprint when fragmentation is high.
2
Identify the configuration setting designed to mitigate fragmentation-induced OOM crashes.
The maxfragmentationmemory-reserved setting defines the buffer size in megabytes reserved specifically to absorb memory fragmentation.
Having this setting configured forces Redis to start reclaiming memory or rejecting writes when the physical memory limit is approached, preventing the OS from terminating the Redis process.
3
Select the correct option that matches the required configuration.
Increasing the maxfragmentationmemory-reserved setting is selected.
This is the targeted setting in Azure Cache for Redis to prevent VM-level OOM crashes caused by memory fragmentation.

Anahtar Kavram

Azure Cache for Redis memory management settings and OOM prevention.
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Implement Azure Cache for Redis Configuration and Data Patterns

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