I have an Azure SQL in WEST US and I want to setup the failover grop with EAST US.
would Azure SQL Geo-replication/failover group cause any performance impact? If so, what would be the impact?
Talking about the impact
In case of failure,
There might be 2 scenarios : Planned Failure and Unplanned Failure.
For Planned Failure,
Your primary database i.e. WEST US will first synchronize with secondary database i.e. EAST US. Then the EAST US db will become primary. This will prevent data loss.
For Unplanned Failure,
The secondary db EAST US will immediately takeover as primary db. Data Loss might happen depending on previous synchronization time.
There will be a performance impact in both the cases. Latency will increase. Microsoft has defined some best practices to minimize this impact.
Refer : https://learn.microsoft.com/en-us/azure/azure-sql/database/auto-failover-group-overview?tabs=azure-powershell#failover-groups-and-network-security
Related
I am confused with azure SQL database backup plan (short term backup retention).
As far as i understood,
In DTU purchasing model, no extra charge for backup storage, you only pay for redundancy type (such as LRS,ZRS)
In vCore purchase model, you will have to pay for backup storage.
am i right ?
does that mean , i will not have any backups if do not subscribe to backup storage in vCore ?
further, in azure pricing calculator, in vCore, General purpose option, you have two redundancy drop down options (i am not talking about long term retention plan) , what is the difference between them ?
Thanks.
i will not have any backups if do not subscribe to backup storage in vCore ?
Yes, in vCore, if you do not allocate a storage account for backups, you will not be able to perform backup operations, either manually or automatically. If you believe you do not need backups, then you might be a fool ;), Azure will maintain access to your database according to the standard SLAs but the infrastructure will not provide a way for you to point-in-time restore the state of your database, only backups can adequately do that for you. But the storage costs are usually a very minimal component of your overall spend. Once the backup operation is complete you can download the backup for local storage and then clear the blob, making this aspect virtually cost free, but you will need a storage account to complete the backup process at all.
in azure pricing calculator, in vCore, General purpose option, you have two redundancy drop down options
Are you referring to the Computer Redundancy:
Zone redundancy for Azure SQL Database general purpose tier
The zone redundant configuration utilizes Azure Availability Zones to replicate databases across multiple physical locations within an Azure region. By selecting zone redundancy, you can make your serverless and provisioned general purpose single databases and elastic pools resilient to a much larger set of failures, including catastrophic datacenter outages, without any changes of the application logic. This configuration offers 99.995% availability SLA and RPO=0. For more information see general purpose service tier zone redundant availability.
In the other tiers, these redundancy modes are referred to as LRS (Locally Redundant) and ZRS (Zone Redundant). Think of this your choice on what happens when your data centre is affected by some sort of geological or political event that means the server cluster, pod or whole data centre is offline.
Locally Redundant offers redundancy only from a geographically local (often the same physical site). In general this protects from local hardware failures but not usually against scenarios that take the whole data center off-line. This is the minimal level of redundancy that Azure requires for their hardware management and maintenance plans.
Zone Redundant offers redundancy across multiple geographically independent zones but still within the same Azure Region. Each Azure availability zone is an individual physical location with its own independent networking, power, and cooling. ZRS provides a minimum of 99.9999999999% durability for objects during a given year.
There is a third type of redundancy offered in higher tiers: Geo-Redundant Storage (GRS). This has the same Zone level redundancy but configures additional replicas in other Azure regions around the world.
In the case of Azure SQL DB, these terms for Compute (So the actual server and CPU) have almost identical implications as that of Storage Redundancy. So with regard to available options, the pricing calculator is pretty well documented for everything else, use the info tips for quick info and go to the reference pages for the extended information:
The specifics are listed here: Azure Storage redundancy but redundancy in Azure is achieved via replication. That means that an entire workable and usable version of your database is maintained so that in the event of failure, the replica takes the load.
A special feature of replication is that you can actively utilise the replicated instance for Read Only workloads, which gives us as developers and architects some interesting performance opportunities for moving complex reporting and analytic workloads out of the transactional data manipulations OOTB, traditionally this was a non-trivial configuration.
The RA prefix on redundancy options is an acronym for Read Access.
I use Cosmos DB with multi-region write in two regions and I need to know what will happen if one of this regions fails (outages).
Will it be data loss and if, yes, how much time will it take to recovery?
Maybe someone faced in his project with a situation when in Cosmos DB with multi-region write one of the region outages and can share his experience?
Was there any data loss and how long did it take to recover in your case?
Documentation says that that there is a possibility of data loss, but there is no clear information about how much data can be lost (such as a calculation formula or something similar), also there is no information about the time. "Given the internal Azure Cosmos DB architecture, using multiple write regions doesn't guarantee write availability during a region outage. The best configuration to achieve high availability during a region outage is single write region with service-managed failover."
https://learn.microsoft.com/en-us/azure/cosmos-db/high-availability#what-to-expect-during-a-cosmos-db-region-outage
I have an Azure SQL in WEST US with GEO-REPLICATION enabled to sync with EAST US.
and I want to know
How often Geo-Recovery sync gets executed to keep the EAST US up to date?
In case of WEST US regional failure and happen to failover to EAST US, would there be any data loss?
Update:
Automated backups, according to this documentation: Both SQL Database and SQL Managed Instance use SQL Server technology to create full backups every week, differential backups every 12-24 hours, and transaction log backups every 5 to 10 minutes. The frequency of transaction log backups is based on the compute size and the amount of database activity.
According to this documentation, if an outage is detected, Azure waits for the period you specified by GracePeriodWithDataLossHours. The default value is 1 hour. If you cannot afford data loss, make sure to set GracePeriodWithDataLossHours to a sufficiently large number, such as 24 hours. Use manual group failover to fail back from the secondary to the primary.
According to this answer, Grace period means to allow time for the database to failover within the primary region.
We have a database located in North Europe region with 2 nodes of AppServices on Azure (West Europe & North Europe). We use traffic manager to route traffic.
Our SQL database and storage are located in Northern Europe.
When we started the website, European locations were the closest to our customers.
However, we saw a shift and most of our customers now are from USA.
We have high CPU utilization on our processors although we have a lot of instances on each.
The question is:
Since most of our customers are from USA and it's hard to relocate the database, is it better to keep the app structure as it is (N. Europe & W. Europe) or create a new node in USA but this node will still need to communicate with the database in North Europe?
Thank you
Having you app in US region and Database in Europe is not recommended.
These are a few of the things you will run into:
1) High latency since the queries for data will have to round-trip to Europe to get this.
2) Higher resource utilization since in general each request that access the DB will take longer, this will increase memory usage while requests are waiting on data it will also make the impact of load a lot more severe on the app.
3) cross region data egress, you will need to pay for all the data moving from Europe to us every-time there is a query.
A better solution would be to do the following:
1) Setup a new DB in us region and hook up active geo-replication
At this point you will have a hot/cold configuration where any instance can be used to read data form the DB but only the primary instance can be used for write operations.
2) Create a new version of the App/App Service plan in US region
3) Adapt your code to understand your geo distributed topology.
You App should be able to send all reads to the "closest" region and all writes to the primary database.
4) Deploy the code to all regions
5) add the new region to TM profile
While this is not ideal since write operation might still have to jump the pond, most apps have a read write patter than is heavily askewed towards read operations (roughly 85% reads / 15% writes ) so this solution works out with the added benefit of giving you HA in case one of the regions goes down.
You might want to look at this talk where I go over how to setup a geo distributed app using App Service, SQL Azure and the technique outlined above.
Have you considered sharding your data based on the location of your users? In terms of performance it will be better, You can provide maintenance on off-peak hours of each region. Allow me to recommend you this article.
I'm working on a quiet large and critical application. It's been deployed to azure with 3 web roles and sql azure db.
In case of disaster, we need to be able to restore both web roles and sql azure to different data centers. Could someone please help me how we can restore SQL Azure DB and Web Role(s) to different data center.
The simple answer is that you take regular backups of your SQL Azure database, which can be restored to a database in another datacenter. You will have a problem with the data since the last backup being lost, which becomes a more difficult problem to resolve — the simplest may be to have a hot standby and use SQL Database Data Sync, but it may not be practical for all the data. Web roles are easier — you redeploy them somewhere else, and change the connection strings to the database. You would also have to change the CNAME for your domain as they will be restored to a different cloudapp.net name.
You did ask for restore, and not failover, right? Performing a failover (where you have a hot standby) is a more difficult problem, particularly as far as data synchronisation is concerned.
I would go back and question 'disaster' and correlate with known facts. I am not sure of the outage history of Azure in specific data centres, but there have been significant Azure-wide outages (leap year 2012 and the certificate problem this year). The ability to restore to a different Azure datacentre won't help you in these scenarios. (Although AWS seems to mostly have regional outages) I don't think that a datacenter-specific recovery strategy is necessary on Windows Azure, but you may want to check the history and likelihood of datacenter-specific failures before making a final call. Having a multi-region architecture that distributes load and data across datacentres, and handles live traffic across all (say using traffic manager), has many benefits — of side effect being builtin-disaster recovery - but comes at an architectural, development, hosting and bandwidth cost.
Go back and write the business case for your datacenter disaster recovery scenario. You may find that it is not worth it financially, or doesn't solve your real problem.