When do ONTAP metrics measure round trip time to clients or only internal ONTAP time?
Applies to
- ONTAP 9
- ONTAP S3 Server
- FCP
- iSCSI
- CIFS
- NFS
Answer
NAS
- NAS protocols (CIFS/NFS) only measure the time the CIFS/SMB/NFS request packet was ingested to the Network layer, processed, and response completed at Network layer.
- There is some time not covered between the Network layer and the packet being sent on the wire, but this is minimal.
- If viewing in Wireshark, you will see the NFS/SMB response time (Service Response Time, or SRT) after the request.
- Each protocol does split a large read or write into chunks, but the network time is not tracked for this.
SAN
- SAN protocols use the SCSI protocol, and as such have the SCSI header, response, and completion.
- More details are in this KB.
ONTAP S3 Server
- The S3 protocol is similar because it can be many megabytes per request, so the TCP delay between request and final completion can be tracked in the Network delay center.
- Large reads or writes (GETs/PUTs) may be split up into chunks, and this is tracked.
- This graphic shows some of the delays possible in the
Network
column ofqos statistics volume latency show
Additional Information
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