I need to make sure the availability of my database is high. working with SQL Azure does not make that clear.
Is there a way to run multi servers (one will take over if one server fails? ) under SQL Azure, above that is there something equivalent to increasing memory on the DB server to speed up the Database processing ?
Read High Availability on the Intro the Azure SQL and then read Business Continuity in Windows Azure SQL Database. To summarize:
Data durability and fault tolerance is enhanced by maintaining
multiple copies of all data in different physical nodes located across
fully independent physical sub-systems such as server racks and
network routers. At any one time, Windows Azure SQL Database keeps
three replicas of data running—one primary replica and two secondary
replicas.
Right now there is no way to specify hardware configuration for SQL Azure Databases. It's totally out of your control and from SAAS perspective that makes sense. The backend management services are responsible making sure you get the best performance possible.
If you need dedicated and reserved hardware for your SQL deployment you may take a look at IAAS offerings in Azure and start a VM with SQL installed however you need to make sure you know the main differences between a IAAS and PAAS offering.
I do not know what your high availability requirements are, but you should look at the SLAs provided by Microsoft. SQL Database offers 99.9% monthly availability.
Related
What is the maintenance required from an organization when deploying an Azure SQL Database in the long term?
My current organization is hoping to do as little database management as possible, and have looked for products that fully manage our databases without much intervention needed from our end. Some products that are being considered includes Snowflake (for their automated partitioning of tables) and Domo (for their data warehousing, connectors, and BI tool offerings).
I'm leaning towards using Azure SQL DB for multiple reasons (products offered, transparent pricing, integration ease, available documentation, SSO, etc.), but want to first understand the skills needed and ease in maintaining it in the long run.
Will we have to manually rebuild indexes and partition out tables as we scale up? Or is Azure intelligent enough that it'll do most of the heavy lifting of performance optimization itself?
Does Azure or other vendors provide services to optimize a DB?
Sorry for the vague prompts, but any additional considerations in choosing DB vendors would be great. Thanks!
Actually for your questions, you should know what is Azure SQL database and it's capabilities.
I'm leaning towards using Azure SQL DB for multiple reasons (products offered, transparent pricing, integration ease, available documentation, SSO, etc.), but want to first understand the skills needed and ease in maintaining it in the long run.
This document What is Azure SQL Database service introduced almost all message you want to know. SQL Database is a general-purpose relational database managed service in Microsoft Azure that supports structures such as relational data, JSON, spatial, and XML. SQL Database delivers dynamically scalable performance within two different purchasing models: a vCore-based purchasing model and a DTU-based purchasing model. SQL Database also provides options such as columnstore indexes for extreme analytic analysis and reporting, and in-memory OLTP for extreme transactional processing. Microsoft handles all patching and updating of the SQL code base seamlessly and abstracts away all management of the underlying infrastructure.
Will we have to manually rebuild indexes and partition out tables as we scale up? Or is Azure intelligent enough that it'll do most of the heavy lifting of performance optimization itself?
No, you don't. Scalability is one of the most important characteristics of PaaS that enables you to dynamically add more resources to your service when needed. Azure SQL Database enables you to easily change resources (CPU power, memory, IO throughput, and storage) allocated to your databases.
You can mitigate performance issues due to increased usage of your application that cannot be fixed using indexing or query rewrite methods. Adding more resources enables you to quickly react when your database hits the current resource limits and needs more power to handle the incoming workload. Azure SQL Database also enables you to scale-down the resources when they are not needed to lower the cost.
For more details, please reference: Scale Up/Down.
Does Azure or other vendors provide services to optimize a DB?
As Woblli said, Azure SQL database provides the Azure SQL database Monitoring and tuning for you.
As a complement, you also can use Azure SQL Database Automatic tuning to help you optimize the database automatically.
Hope this helps.
Azure SQL DB offers the services you're asking.
You can enable automatic tuning, which will create and drop indexes based on performance gains. Force good query plans again based on performance. It will roll back changes if the specific change has decreased the overall database performance level.
It will not partition or shard your database for you however.
Official documentation:
https://learn.microsoft.com/en-us/azure/sql-database/sql-database-automatic-tuning
I have finally got the time to start looking at Azure. It's looks good and easy scaling.
Azure SQL, Table Storage and Blog Storage should cover most of my things. Fast access to data, auto replication and failover to an other datacenter.
Should the idea come for an app that needs fast global access the Traffic manager is there and one can route users for "Fail Over" or "Performance".
The "performance" is very nice for Cloud Services and "Web Roles / Worker Roles" ... BUT ... What about access to data from SQL Azure/Table Storage/Blog Storage.
I have tried searching the web(for what to do about this need), but haven't found anything about the traffic manager that mentions anything about how to access data in such a scenario.
Have I missed anything?
Do people access the storage in the original data center (and if that fails use the Geo Replication feature)? Is that fast enough? Is internal traffic on the MS network free across datacenters?
This seems like such a simple ...
Take a look at the guidance by Microsoft: Replicating, Distributing, and Synchronizing Data. You could use the Service Bus to keep data centers in Sync. This can cover SQL Databases, Storage, search indexes like SolR, ElasticSearch, ... The advantage over solutions like SQL Data Sync is that it's technology independent and it can keep virtually all your data in sync:
In this episode of Channel 9 they state that Traffic Manager is only for Cloud Services as of now (Jan 2014) but support is coming for Azure Web Sites and other services. I agree that you should be able to ask for a Blob using a single global URL and expect that the content will be served from the closest datacenter.
There isn't a one-click easy to implement solution for this issue. The way you solve it will depend on where the data lives (ie. SQL Azure, Blob storage, etc) and your access patterns.
Do you have a small number of data requests that are not on a performance critical path in your code? Consider just using the main datacenter.
Do you have a large number of read-only type of requests? Consider doing a replication of the data to another datacenter.
Do you do a large number of read and only a few write operations? Consider duplicating the data among all datacenters and each write will write to all datacenters at the same time (incurring a perf penalty) and do all reads to the local datacenter (fast reads).
Is your data in SQL Azure? Consider using SQL Data Sync to keep multiple datacenters in sync.
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.
How do I see if an SQL Azure database is being throttled?
I want to see data like: what percentage of time it was throttled, the count of throttles, the top reasons of throttles.
See https://stackoverflow.com/questions/2711868/azure-performance/13091125#13091125
Throttling is the least of your troubles. If you need performance then you would be best served to build your own DB servers using VM roles. I found that the performance of these is vastly improved over SQL Azure. For fault tolerance you can provision a primary and a failover in a different VM in a different region if necessary. Make sure that the DB resides on the local drive.
I don't believe that information is currently available. However, the team does share reasons why you could be throttled and how to handle it (see here).
AFAIK Amazon AWS offers so-called "regions" and "availability zones" to mitigate risks of partial or complete datacenter outage. Looks like if I have copies of my application in two "regions" and one "region" goes down my application still can continue working as if nothing happened.
Is there something like that with Windows Azure? How do I address risk of datacenter catastrophic outage with Windows Azure?
Within a single data center, your Windows Azure application has the following benefits:
Going beyond one compute instance, your VMs are divided into fault domains, across different physical areas. This way, even if an entire server rack went down, you'd still have compute running somewhere else.
With Windows Azure Storage and SQL Azure, storage is triple replicated. This is not eventual replication - when a write call returns, at least one replica has been written to.
Ok, that's the easy stuff. What if a data center disappears? Here are the features that will help you build DR into your application:
For SQL Azure, you can set up Data Sync. This facility synchronizes your SQL Azure database with either another SQL Azure database (presumably in another data center), or an on-premises SQL Server database. More info here. Since this feature is still considered a Preview feature, you have to go here to set it up.
For Azure storage (tables, blobs), you'll need to handle replication to a second data center, as there is no built-in facility today. This can be done with, say, a background task that pulls data every hour and copies it to a storage account somewhere else. EDIT: Per Ryan's answer, there's data geo-replication for blobs and tables. HOWEVER: Aside from a mention in this blog post in December, and possibly at PDC, this is not live.
For Compute availability, you can set up Traffic Manager to load-balance across data centers. This feature is currently in CTP - visit the Beta area of the Windows Azure portal to sign up.
Remember that, with DR, whether in the cloud or on-premises, there are additional costs (such as bandwidth between data centers, storage costs for duplicate data in a secondary data center, and Compute instances in additional data centers). .
Just like with on-premises environments, DR needs to be carefully thought out and implemented.
David's answer is pretty good, but one piece is incorrect. For Windows Azure blobs and tables, your data is actually geographically replicated today between sub-regions (e.g. North and South US). This is an async process that has a target of about a 10 min lag or so. This process is also out of your control and is purely for a data center loss. In total, your data is replicated 6 times in 2 different data centers when you use Windows Azure blobs and tables (impressive, no?).
If a data center was lost, they would flip over your DNS for blob and table storage to the other sub-region and your account would appear online again. This is true only for blobs and tables (not queues, not SQL Azure, etc).
So, for a true disaster recovery, you could use Data Sync for SQL Azure and Traffic Manager for compute (assuming you run a hot standby in another sub-region). If a datacenter was lost, Traffic Manager would route to the new sub-region and you would find your data there as well.
The one failure that you didn't account for is in the ability for an error to be replicated across data centers. In that scenario, you may want to consider running Azure PAAS as part of HP Cloud offering in either a load balanced or failover scenario.