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June 26th, 2023 12:00
Do the Powervault ME4 and ME5 series support both receive and transmit flow control?
Per this best-practices page here for the ME4 and ME5, they both say this:
We recommend the following settings when enabling flow control:
- Enable a minimum of receive (RX) flow control for all switch interfaces used by servers or storage systems for iSCSI traffic.
- Enable symmetric flow control for all server interfaces used for iSCSI traffic. PowerVault ME5 automatically enables this feature.
So the usage of the word "minimum" made me curious as to whether Dell would actually recommend MORE than just receive - that actually, Dell is saying that if our switches support it, they are recommending enabling both receive and transmit flow control.
So I want to confirm - both the ME4 and ME5 support symmetric, receive and transmit flow control, not just receive? We are coming from a compellent which only supported receive.
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DELL-Charles R
Moderator
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4.6K Posts
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June 27th, 2023 08:00
Hello HornHead,
It is going to be a switch setting and not a storage setting.
You'll want it on, on the switch port that has the storage connected.
Reference the Support Matrix for both storage in the rules section:
ME4 Support Matrix
Page 7 : https://dell.to/3XsqMn2
ME5 Support Matrix
Page 7: https://dell.to/3JyxKkx
DellEMCSupport
631 Posts
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June 26th, 2023 19:00
Hello thanks for choosing Dell. This is more in the consulting area than after-sales-tech-support: Maybe this article could help. https://dell.to/43XUkvm
HornHead
14 Posts
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June 27th, 2023 07:00
Oh yes, Moderator... we paid for a very expensive warranty for our ME5084. If I want to make a support ticket with Dell EMC I certainly will. I was just trying to gauge whether or not Dell actually recommends both receive and transmit on my switches, or just receive. I really don't know how to interpret "minimum of receive"... will we potentially have better performance in high I/O situations if both receive and transmit is able to use the PAUSE frame?
That article you linked is more or less the same text, verbatim, as what my ME4 and ME5 links state, unfortunately. I'd like something a little more authoritative than "minimum of"
HornHead
14 Posts
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June 27th, 2023 09:00
Ah yes - perfect, page 7 seems to the answer, quote (emphasis mine):
"iSCSI network rules:
● If the iSCSI initiators are connected to ME5 Series storage
systems through the network switches, ensure that your switches
support IEEE 802.3x flow control, and the flow control is enabled
for both sending and receiving on all switch ports and server NIC
ports"
Thank you, that will suffice!