December 16, 2019 at 11:29 pm
When SQL2008/2008R2 was supported, I virtualized SQL server and I still have one cluster of VMs(VMWare), which will be upgraded sometime next year. For the two SQL 2016 clusters, both are physical servers, each of 12-physical cores. From SQL Server core licensing model, I don't see the benefit of virtualization. On physical box, hyperthreading will provide 10-15% performance gain and it's free(SQL licensing is the same with or without HT);
On VM, hyperthreading is enabled on the host level, with only 10-15% gain, SQL licensing will double since each vCPU requires one license, plus the cost of VMWare.
Physical box provides dedicated resource, and I do the same on virtualized instance: reserve CPU/Memory for SQL server.
When upgrading, I need to upgrade the OS and SQL server, so VM does not provide any benefit than a physical one.
This is probably against the trend, but it worked well for me and for the employer. How much do you virtualize your SQL server?
December 17, 2019 at 10:16 am
If you license your box for SQL Enterprise and if you have software assurance costs do not increase with virtualization. Without SA or with SQL Standard then yes it does increase
In my shop we have over 2200 VM's - over 200 ESX Hosts and a few are exclusive for SQL - where the physical box is licensed (Ent + SA) - with over 400 SQL Instances
December 17, 2019 at 12:49 pm
It's not always about performance. My company has largely stopped buying servers (I think, one in the last 6-7 years). Instead, we're hosting most things on VMs online, or in services online. Performance through a VM can be adequate, or even good. It really depends on your systems, your needs and your load. It may be that you're in a situation where iron is the only solution. Lots and lots of others are not.
In addition to straight VM or not VM, also look at some of the management and DR scenarios that virtualization can offer. Sometimes people will sacrifice a little performance for a better DR solution.
But, frankly, if iron is working for you, stay with it. Nothing says you're required to move to VMs.
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December 18, 2019 at 5:09 pm
thank you, Grant and Frederico_fonseca. On cluster is still on virtual, performance on VM is acceptable and it's not the issue. The main reason is the cost: double SQL server licensing fee and vmware cost.
I ran into vMotion twice. The first time, during normal hours, infrastructure team tested the vMotion feature without telling anyone and the sql server failed over; the second time, off peak, I was notified and for testing only, still failed over. As a DBA, I have no access to VM hosts. I cannot access this feature.
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