Skip to main content
NetApp Knowledge Base

SAN increased latency with low throughput from VAAI Copy Offload

  1. Last updated
  2. Save as PDF
Views:
337
Visibility:
Public
Votes:
0
Category:
ontap-9
Specialty:
perf
Last Updated:

Applies to

  • ONTAP 9
  • VAAI Copy Offload
  • Data ONTAP 8 7-Mode

Issue

  • System Manager dashboard displays a high LUN latency without a significant increase in IOPS or throughput.
  • High latency is mostly with SAN Other operations. 
  • HDD read/write or SSD read/write is much higher than FCP in/out or iSCSI in/out from the sysstat -x outputs. 
    • If VAAI Copy Offload source volume and destination volume are from the same node, Net in/out is as low as FCP in/out or iSCSI in/out in sysstat -x.
    • If VAAI Copy Offload source volume and destination volume are from different nodes, Net in/out is as high as HDD read/write or SSD read/write in sysstat -x.

Example 1: 

System Manager dashboard displays a high LUN latency

Notes:

  • iSCSI + HDD
  • VAAI Copy Offload Source volume and Destination volume on the same node
  • Net in/out & iSCSI in/out are both much lower than HDD read/write

Example 2:

System Manager dashboard displays a high LUN latency

Notes: 

  • FCP + SSD
  • Source volume and Destination volume are from different nodes
  • This is the Source node
  • Net out is as high as SSD read, and they are both much higher than FCP out

Example 3: 

SAN increased latency with low throughput from VAAI Copy Offload

Notes:

  • FCP + SSD
  • Source volume and Destination volume are from different nodes
  • This is the Destination node
  • Net in is as high as SSD write, and they are both much higher than FCP in

Sign in to view the entire content of this KB article.

New to NetApp?

Learn more about our award-winning Support

NetApp provides no representations or warranties regarding the accuracy or reliability or serviceability of any information or recommendations provided in this publication or with respect to any results that may be obtained by the use of the information or observance of any recommendations provided herein. The information in this document is distributed AS IS and the use of this information or the implementation of any recommendations or techniques herein is a customer's responsibility and depends on the customer's ability to evaluate and integrate them into the customer's operational environment. This document and the information contained herein may be used solely in connection with the NetApp products discussed in this document.