PowerFlex IO Errors Received After SDC Failed To Reconnect With A Decoupled SDS

Summary: Issue Description A client host reports I/O errors when a disconnected SDS reconnects to the system.

This article applies to This article does not apply to This article is not tied to any specific product. Not all product versions are identified in this article.
Check out other resources

Symptoms

MDM events show that the SDS rejoins the cluster:

2022-05-17 03:17:00.127 SDS_RECONNECTED           INFO     	 SDS:  () reconnected.

ESXi logs show recurring "failed to send for 180 interactions" events that eventually lead to I/O hard errors against the volume:

2022-05-17T04:33:11.925Z cpu53:2098393)WARNING: PowerFlex netCon_IsKaNeeded:4338 :Error: CON 0x45b9517e4d40 failed to send for 180 iterations. Marking as down
2022-05-17T04:33:11.925Z cpu53:2098393)WARNING: PowerFlex netCon_IsKaNeeded:4338 :Error: CON 0x45b9517e3f40 failed to send for 180 iterations. Marking as down
..
2022-05-17T04:33:21.275Z cpu36:2098514)ScsiDeviceIO: 4267: Cmd(0x45d96d40ab00) 0x28, CmdSN 0x800e0030 from world 3589861 to dev "" failed H:0x0 D:0x2 P:0x0 Valid sense data: 0x4 0x0 0x0

 

Impact

SDC/s may receive I/O errors. SDC datastores may go into a Read-Only state.

Cause

When an SDC-SDS TCP connection is terminated suddenly and not in an orderly fashion (TCP FIN packets not sent), for example in cases of a switch failure or a power outage/hard reset of an SDS host, the sockets may remain open on the SDC side, and remain stuck in the "security handshake" phase due to a software code issue that was introduced in version 3.5.

In this situation, the state of these stuck connections is considered "not connected", and even if the SDS host becomes reachable again, the "stuck" connections are not renewed.

Due to platform-specific implementations of the SDC network layer, this issue cannot occur in Linux SDCs.

 

Resolution

Workaround

The "SDS Proxy" feature that was introduced in version 3.6 greatly reduces the probability of the issue occurring.

An afflicted SDC host can be rebooted.

Impacted Versions

PowerFlex SDC version 3.5 and higher

Fixed In Version

PowerFlex 3.5.1.7

PowerFlex 3.6.0.5

Affected Products

PowerFlex rack, VxFlex Product Family
Article Properties
Article Number: 000202229
Article Type: Solution
Last Modified: 18 Mar 2025
Version:  4
Find answers to your questions from other Dell users
Support Services
Check if your device is covered by Support Services.