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ltpolaris
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LUN Queue Depth on Emulex HBA

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In the Host Configuration Guide, on page 59, it talks about setting the LUN queue depth on the Emulex HBA to 128.

The document also has a table that prescribes settings for a mixed storage environment. (in my case, XIO and VNX)

That table has no recommendation for LUN queue depth on the HBA module. It does talk about the per LUN SchedNumReqOutstanding parameter, which I would set to 256 for all XIO LUNS.

My question is, with a mixed storage environment, should I be adjusting the HBA LUN queue depth to the prescribed XIO settings or leaving them at the default (which I think in this case is 30)

Advice greatly appreciated

Thanks, Jim

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mabela
2 Bronze

Re: LUN Queue Depth on Emulex HBA

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Because you reference schednumreqoutstanding parameter, i am assuming you are trying to achieve this in a VMware environment. For queue depth there are two settings that can be adjusted: LUN Queue Depth, and HBA Queue Depth (IO throttle count). For Emulex, XtremIO best practice recommendation is to set HBA Queue Depth to 8192(default), and Lun Queue depth to 128. However, since your vhbas also have VNX, you need to go with lowest value which would be of VNX. Therefore, you would set Lun Queue Depth to 32, and HBA queue depth (if same vhba as VNX) to the VNX one. However, since you are using Emulex, and Emulex HBAs typically have the driver for these HBAs preloaded with ESX, you can stay with the default of 8192.

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mabela
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Re: LUN Queue Depth on Emulex HBA

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Hi,

Check out this post which should explain exactly what you are looking for - Connecting EMC XtremIO To An Heterogeneous Storage Environment – Itzikr's Blog. In summary, go with the lowest number, but just know you may not be getting the best performance out of your XtremIO.

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ltpolaris
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Re: LUN Queue Depth on Emulex HBA

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Thank you. Yes, I have reviewed that blog, and the same guidance is in the Host Configuration Guide.

However, I cannot see where the specific configuration parameter I am asking about is discussed, thus my request for clarification.

If I somehow missed it, please point me to the specific guidance

Thanks, Jim

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mabela
2 Bronze

Re: LUN Queue Depth on Emulex HBA

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Because you reference schednumreqoutstanding parameter, i am assuming you are trying to achieve this in a VMware environment. For queue depth there are two settings that can be adjusted: LUN Queue Depth, and HBA Queue Depth (IO throttle count). For Emulex, XtremIO best practice recommendation is to set HBA Queue Depth to 8192(default), and Lun Queue depth to 128. However, since your vhbas also have VNX, you need to go with lowest value which would be of VNX. Therefore, you would set Lun Queue Depth to 32, and HBA queue depth (if same vhba as VNX) to the VNX one. However, since you are using Emulex, and Emulex HBAs typically have the driver for these HBAs preloaded with ESX, you can stay with the default of 8192.

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ltpolaris
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Re: LUN Queue Depth on Emulex HBA

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That is what I was looking for. (LUN Queue Depth)..

Thanks again

Jim

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