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Kevin_Boyle
Enthusiast
Enthusiast

Do RAID0 options impact performance or data integrity?

I'm configuring a new vSAN cluster. All components are on the HCL.

I have three hosts: Intel S2600GZ servers

  • 32 GB RAM
  • X540-T2 nic (1)
  • S3700 Series SSD 100GB (1)
  • Seagate 1TB 7200RPM SAS HD (3)
  • Intel RS25DB080 PCIe 2.0 x8 RAID controller (1)

With the RS25DB080, I have to configure each HD as a RAID0 array. During the array configuration I have most of the standard RAID0 configuration options including Write-Through / Write-Back, stripe size, etc. but I can't find any documentation discussing which are appropriate for a vSAN deployment.

I assume I want Write-Through since vSAN is using the SSD for caching. Is there an optimum stripe size?

5 Replies
CHogan
VMware Employee
VMware Employee

Our recommendation would be to disable controller cache if you can - we already take care of caching data in VSAN.

If you cannot disable the cache on the controller, then set it to 100% read (which effectively disables the write cache).

There are no other recommendations per se - you can leave the rest of the settings as default.

I'm not aware of any performance/data integrity issues with either RAID-0 or pass-through. However there maybe additional overhead when it comes to drive replacement, as you may have to create a RAID-0 configuration on the replacement drive. With passthru, it should be a matter of plug-n-play.

HTH

Cormac

http://cormachogan.com
jgaleano
Enthusiast
Enthusiast

Hi John

The answer that Cormac wrote back is correct, right know we have a VSAN environment so like yours with 3 hosts and their disks in raid 0, but if you don’t install a controller driver that allow you to erase raid, create raid, put offline disks and bring it online it would be difficult to change a disk when it fails.

I highly recommend you to find an adequate driver that allows you to do storcli in the ESXi.

Best Regards.

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Kevin_Boyle
Enthusiast
Enthusiast

Hi Cormac,

I'll look into the cache options. 🙂

Julian mentioned StorCLI. I have seen other references to it too but nothing that describes just how it benefits a VMware system.

  • Is this a supported way to do things?
  • Are you aware of any documentation that describes how it can be used to overcome RAID0 limitations?
  • Do you know if it will allow the controller to be configured in pass-through mode?

Intel does have a StorCLI Phase 2.0 driver:

https://downloadcenter.intel.com/Detail_Desc.aspx?DwnldID=24484&lang=eng

I assume I would have to install it on each ESXi host?

Thanks...

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Kevin_Boyle
Enthusiast
Enthusiast

Do  you have any information you can share regarding my December 4th post?

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jgaleano
Enthusiast
Enthusiast

Hi Kevin

Sorry I didn’t see your post.

About your question i assume that you should install it in each host to let you manage the controller of each host.

In our environment we have LSI controllers and in each host we must install the driver and load it with a reboot, then we are able to manage our controller, create raids, remove raids, etc.

I don’t know if it’s fully supported but it does works for us.

The pass-through feature depends on each controller model, you should check your hardware documentation to find if your controller supports pass-through

Hope this helps you.

Best Regards.

Julian