Exam AZ-204 topic 5 question 31 discussion

The key here is "In case of an Azure data center outage, metadata loss must be kept to a minimum." So the correct answer is AC.

got it 10/09/2022. went with AC. Score 927

A & B are the correct answers

A: Configure Azure Redis with AOF persistence. D: Set backup frequency to the minimum value.

Copilot: While option A (Configure Azure Redis with AOF persistence) is indeed a valid action, option C (Configure second storage account for persistence) is not directly related to the configuration of Azure Redis Cache. Option C suggests setting up a second storage account, which could be part of a broader disaster recovery strategy, but it doesn’t directly affect the configuration of the Azure Redis Cache instance. It’s more about the overall architecture of your application. Therefore, the most appropriate actions to minimize metadata loss in case of an Azure data center outage would be: A. Configure Azure Redis with AOF persistence. D. Set backup frequency to the minimum value. These actions ensure that every write operation is logged and that backups are created as frequently as possible, respectively. This combination provides the best protection against data loss in the event of an outage.

In my opinion this question refers to the durability of the data and not to the availability. On the one hand AOF persistence does not support ZRS (availability) but on the other hand AOF persistence ensures the minimum data loss (durability)

Technically here could be just 2 valid answer: AC and BD. But, we need to select the option mostly matching the requirements. Since, they ask to minimize data loss (rather than speed of recovery) then AC is the right answer, because: 1) With AOF persistence every write transaction is logged. So, in theory we can recover everything up to the moment of failure. 2) Additionally, we'll enable Secondary Storage for AOF, which will help to restore Redis image if primary zone was fully destroyed. Why RDB is worse? Even if we minimize the period of snapshotting to minimum (15 mins), then we can lose up to 15 mins of data in case of data center outage. Though advantage is that we can restore the snapshot much faster than from the AOF logs. You can find full info about AOF and RDB settings in Azure Redis Cache on this link: https://learn.microsoft.com/en-us/azure/azure-cache-for-redis/cache-how-to-premium-persistence?tabs=premium

https://redis.io/docs/management/persistence/ Ok, so what should I use? If you care a lot about your data, but still can live with a few minutes of data loss in case of disasters, you can simply use RDB alone.

B,D is correct Zone redundancy doesn't support AOF persistence or work with geo-replication currently", meaning it shouldn't be A because "In case of an Azure data center outage, metadata loss must be kept to a minimum. https://learn.microsoft.com/en-us/azure/azure-cache-for-redis/cache-how-to-zone-redundancy

https://learn.microsoft.com/en-us/training/modules/develop-for-azure-cache-for-redis/3-configure-azure-cache-redis The Premium tier allows you to persist data in two ways to provide disaster recovery: RDB persistence takes a periodic snapshot and can rebuild the cache using the snapshot in case of failure. AOF persistence saves every write operation to a log that is saved at least once per second. This creates bigger files than RDB but has less data loss. So AOF has less data loss which satisfies the requirement. So AOF with data written is a second storage account with ZRS should do the job. I would also go with AC

A,C chatGPT!

AOF leverage on the second storage account: With AOF persistence enabled, write operations to the cache are saved to the named storage account (or accounts if you've configured a second storage account). If there's a catastrophic failure that takes down both the primary and replica cache, the stored AOF log is used to rebuild the cache.

Goodluck!

Options C and D are not relevant for this scenario. Configuring a second storage account is not necessary since Redis cache already has persistence options available. Setting backup frequency to minimum value is also not necessary since AOF and RDB persistence options already ensure that data is regularly saved to disk.

finnishr is right

finnishr is correct

So many misleading guys, don't answer if you are not sure! Why do you think it's AC? "Zone redundancy doesn't support AOF persistence or work with geo-replication currently", meaning it shouldn't be A because "In case of an Azure data center outage, metadata loss must be kept to a minimum". And it's meaningless to use another storage account so it should not be C.