Network and Storage Protocols

the Linux admin is trying to confirm if we can change the SVM "Target Max Recv Data Length" to match

Knowledgexchange
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would like to know if there are any use cases to match the initiator & target mrdsl for OLAP (sequential) workload.

Can you verified with your team, if that parameter would affect the performance of OLAP (seq) vs OLTP (random) workload.

As the Linux admin is adamant that performance would suffer unless that “target-mrdsl” parameter on the target (NetApp) matches the initiator (Linux) “initiator-mrdsl” for the OLAP (sequential) workload.

 

1 ACCEPTED SOLUTION

hmoubara
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Hello,

 

The initiator or target declares the maximum data segment length in bytes it can receive in an iSCSI PDU.
so per example, if an initiator advertised MRDSL=16MB, that would mean that the initiator is willing to accept PDUs with
a data segment UP TO 16MB. ONTAP never sends a PDU larger than 64KB, but since 64KB < 16MB, this would not be a compliance or interop issue.

 

Hope this answer your question.

 

Thanks

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2 REPLIES 2

hmoubara
639 Views

Hello,

 

The initiator or target declares the maximum data segment length in bytes it can receive in an iSCSI PDU.
so per example, if an initiator advertised MRDSL=16MB, that would mean that the initiator is willing to accept PDUs with
a data segment UP TO 16MB. ONTAP never sends a PDU larger than 64KB, but since 64KB < 16MB, this would not be a compliance or interop issue.

 

Hope this answer your question.

 

Thanks

Knowledgexchange
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Re: “ONTAP never sends a PDU larger than 64KB, but since 64KB < 16MB, this would not be a compliance or interop issue.”

 

So ONTAP would not send out (target-mrdsl) larger than 64KB regardless of the workload (random or sequential)?

 

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