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Question
Friday, March 8, 2019 6:10 PM
I am not a server expert here, but I am a general admin, so I'll try to keep up ;) I know that versions of this question have been asked, but the answers vary. Hypothetically, I have a server, with a 1TB OS drive, and a 10TB data drive. We are going to run SQL and a proprietary application that keeps the Database updated. We want to make this a highly available server, so we have an identical server that we want to use (along with the first one) to create a two node cluster.
From what I am reading, there are people saying that I cannot create a cluster using servers with local storage, and must use a SAN or NAS, others are saying yes I can. But there is no definitive answer I've found, and I do not want to spend the money to go from hypothetical to reality, if it can't be done.
The problem with a shared storage like NAS, is that it creates a single point of failure. If the NAS fails (power failure, board failure, fire, etc.), then the Database server cluster fails, and that defeats the whole point of the cluster. Clustering is all about eliminating single points of failure, so NAS is not the solution. SAN seems to me like clustered storage, and makes me wonder why I can't just eliminate the complication of the extra hardware, and utilize the two perfectly good arrays I already have in the existing nodes I'm clustering. A SAN in this case just seems like redundant overkill, and a waste of money. I already have the high availability of the two server cluster, and their identical internal storage arrays, with all the storage I need. Why can't I use them?
Is there a way to cluster two servers, with their own locally attached storage? For example, can I take server A with a C: and a locally attached (eg internally configured RAID array) D: drive, and make server B (configured identically) work in a cluster with server A? And can it be made to work with the OS on C:, and the database on the internal D:, without a NAS or a SAN?
Go...
All replies (8)
Friday, March 8, 2019 6:31 PM
Hello,
The Windows Failover Cluster does require shared storage, so you won't be able to user local storage.
However, you can use third party software (Starwind for example) to accomplish this, or by using SMB 3.0 from another system.
Starwind Virtual SAN provides a software that turns local storage into shared storage.
Here's a link with a scenario for you:
StarWind Virtual SAN Hyperconverged 2-Node Scenario with Hyper-V Cluster on Windows Server 2012R2
Best regards,
Leon
Blog: https://thesystemcenterblog.com LinkedIn:
Friday, March 8, 2019 8:03 PM
YES it's possible,
For example SQL Cluster Always-on can use the Local Storage (identical in each node), no need of SAN or NAS anymore,
_mRS_
Friday, March 8, 2019 8:32 PM
That is right, SQL Always On availability groups does not depend on any form of shared storage.
However, if you use a SQL Server failover cluster instance (FCI) to host one or more availability replicas, each of those FCIs will require shared storage as per standard SQL Server failover cluster instance installation.
Blog: https://thesystemcenterblog.com LinkedIn:
Saturday, March 9, 2019 2:36 PM
In fact, since your question is really more about highly available SQL rather than clustering in general, you will be better served to take your questions to the forum on highly available SQL - https://social.technet.microsoft.com/Forums/en-US/home?forum=sqldisasterrecovery. The experts in that forum are much better prepared to answer questions about highly available SQL than respondents in this forum.
tim
Monday, March 11, 2019 6:28 AM
Hi,
I agree with Moad RAHALI SEMLALI.
If you don’t have a dedicated team of storage engineers who are responsible for a shared storage subsystem, then, Basic Availability Group is the right solution.
Here're some references discussed implementing a SQL HA with local storage, hope this helps.
Implement a SQL Server HA failover solution without shared storage
SQL Failover Cluster without Shared Storage – SQL Server 2012 and SMB
Please Note: Since the web site is not hosted by Microsoft, the link may change without notice. Microsoft does not guarantee the accuracy of this information.
An Availability Group does not require shared storage. Each replica has its own local storage independent of the Availability Group. If the primary replica becomes unavailable and a failover occurs, any secondary replica can take over without having to rely on the availability of the system and user databases from the primary replica. From a capacity point-of-view, you need to provision disk space based on the sizes of the databases and the number of secondary replicas, significantly increasing the cost per gigabyte.
But from an availability point-of-view, because the Availability Group replicas do not rely on a single storage source, the SQL Server instance hosting the replicas remains online regardless of what happens to the primary replica. Each Availability Group replica has its own copy of the system databases, thus, it is always online regardless of whether it is functioning as a primary or a secondary replica. This is also the reason why failover is much faster in an Availability Group than it is in an FCI.
Hope above information can help you. If you have any question or concern, please feel free to let me know.
Best regards,
Michael
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Wednesday, March 13, 2019 8:45 AM
Hi,
Just checking in to see if the information provided was helpful. Please let us know if you would like further assistance.
Best Regards,
Michael
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Monday, March 18, 2019 10:07 AM
Hi,
Could the above reply be of help? If yes, you may mark it as answer, if not, feel free to feed back.
Best Regards,
Michael
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Thursday, March 21, 2019 8:46 AM
Hi,
Please let us know if you need further assistance.
If you find any reply that helps, could you help mark it as an answer so that other community members could find the helpful reply quickly please ? Your contribution is highly appreciated.
Thanks for your support and understanding.
Have a nice day!
Best regards,
Michael
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