MS SQL Server in VMware Cluster

ziorus

n00b
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Jan 10, 2016
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Hi everyone,

We currently have an old SQL Cluster (just 2 modes) on physical servers, which we will be moving to a VMware Cluster infrastructure. My question, since the VMware is already clustered, does it make sense to cluster the SQL again?
 
Joined
Dec 1, 2011
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887
Yes. I'm guessing you want the ability to keep the SQL cluster up while performing updates and such on individual VMs. Or in case one goes down/gets corrupted/etc. Basically all the reasons you presently are running as a cluster.

You can also set up affinity rules (depending on VMware subscription level?) to force the SQL server instances to run on separate hosts. So if one host goes down you still have an instance running on another.
 

JavaLava

Weaksauce
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Apr 3, 2018
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Yes, VMware wont provide application redundancy...so you still need to setup the cluster/AlwaysOn.

Also, while I know you can technically virtualize MS SQL, I would exercise caution and analyze your current I/O performance and compare it to what you will get in the VMware cluster. SANS wont match the performance of direct attached SAS drives which could be a critical factor in DB performance.
 
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ziorus

n00b
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Jan 10, 2016
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Many thanks for your answers. The cluster types would include the standard SQL Cluster and also AlwaysOn, no mirroring.

I am also afraid of the performance but this push is over my pay grade. I have already included that in my risk assessment to this idea/plan. It gets worse because this service provider we are going to, we actually have no clue how their infrastructure is setup and configured. I preferred actual physical machines when it comes to SQL...
 

jlbenedict

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We virtualize sql clusters, but our architecture team is above my pay grade also 🤣

See attached for your reading pleasure
 

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  • sql-server-on-vmware-best-practices-guide.pdf
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Vengance_01

Supreme [H]ardness
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Make sure you do always on. Standard clustering in SQL on Vmware is no bueno
 

SolarBeam

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Jul 11, 2016
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I've recently moved the physical SQL cluster into VMware cluster. The main task was to use FCI approach in the VMware. We have decided to rework storage architecture also and move from old SAN box into something new. Since we need iSCSI storage to be able to create SQL cluster, we have tried different SDS solutions (datacore, starwind, hpe storevirtual) and decided to use starwind vsan free (quite simple to set up and allows to create 2 node storage replication in active-active manner - https://www.starwindsoftware.com/starwind-virtual-san) for iSCSI HA storage sharing. I've pretty much the same setup besides the SDS software is now in charge instead of classic SAN storage.
 

Grimlakin

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Also, while I know you can technically virtualize MS SQL, I would exercise caution and analyze your current I/O performance and compare it to what you will get in the VMware cluster. SANS wont match the performance of direct attached SAS drives which could be a critical factor in DB performance.

That is an incorrect statement. If they have a full flash array with sub MS query times and IOP's in the millions or even just hundreds of thousands this is normally just fine for most databases. It all depends on the solution but a blanket that SAN's are less than direct attached SAS drives is wholly incorrect. CHEAP SAN's are. GOOD San's that have a solid connection like dedicated Fiber HBA's are more than capable of supplying the I/O to an entire host of SQL servers in a Vmware cluster.

But to answer your question if you want 100% uptime even while applying OS and SQL patches and such you still want your cluster. Since a san is involved you can set up your Availability Group with a SAN based SMB share to act as the share witness. That way there are less chances of it going down on you as compared to a dedicated VM hosting your witness that will go down on maintenance and such.
 

Grimlakin

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Doesn't VMWare have its own VSAN solution which can be used for SQL FCI?

VMwares VSAn isn't that great for these types of deployments in my experience. The level of fault tolerance is less and the ability to loose data is in my experience worse. A solid Unity or like attached fiber storage will provide ample performance unless the databases are insanely large/busy.
 
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