Citrix worker VMs hang when running an Endpoint Protection scheduled scan

Products

• Endpoint Protection

Issue/Introduction

You are running Citrix worker VMs in an environment with a Citrix Provisioning Services (PVS) 7.15 Cumulative Update 1 (CU1) target. In the course of a Symantec Endpoint Protection (SEP) scheduled scan, the systems experience a hang.

Dump analysis indicates that the Citrix virtual disk is not processing SCSI requests, as shown by the large amount of Input/Output Request Packets (IRPs) in the Outstanding Requests queue of the relate storport device:

!storunit ffffa18625be1400
   DO: ffffa18625be1400   Ext: ffffa18625be1550   Adapter: ffffa18624d4a1a0   Working
   Vendor: Citrix  Product: Virtual Disk  SCSI ID: (0, 0, 128)
   Claimed Enumerated 
   SlowLock: Free  RemLock: 18  PageCount: 0
   QueueTagList: ffffa18625be1650     Outstanding: Head: 0000000000000000  Tail: 0000000000000000  Timeout: 0 (Ticking Down)
   DeviceQueue: ffffa18625be16e0  Depth: 250  Status: Not Frozen   PauseCount: 0  BusyCount: 0
   IO Gateway: Busy Count: 0  Pause Count: 0
   Requests: Outstanding: 17  Device: 0  ByPass: 0
[...]
[Outstanding Requests]
IRP               SRB Type   SRB               XRB               Command           MDL               SGList            Timeout
-----------------------------------------------------------------------------------------------------------------------------------
ffffa1864d973870  [SCSI]     ffffa1864ce1e1d0  ffffa18624d5c020  SCSI/READ (10)    ffffa1862ecd2d60  0000000000000000  200s
ffffa1864d9714a0  [SCSI]     ffffa1864d7fc1d0  ffffa18625ae4780  SCSI/READ (10)    ffffa1863a208110  0000000000000000  200s
ffffa1864d96f870  [SCSI]     ffffa1864d6ec1d0  ffffa18624d54780  SCSI/WRITE (10)   ffffa1863af4a1a0  0000000000000000  200s
ffffa1864d964a60  [SCSI]     ffffa1864d964bd0  ffffa18624d5e020  SCSI/WRITE (10)   ffffc78014ebefd0  0000000000000000  200s
ffffa1864d9651e0  [SCSI]     ffffa1864d965350  ffffa18624d69780  SCSI/WRITE (10)   ffffc780135cefd0  0000000000000000  200s
ffffa1864d964620  [SCSI]     ffffa1864d964790  ffffa18624d5cbd0  SCSI/WRITE (10)   ffffc78014ecefd0  0000000000000000  200s
ffffa1864d96fc40  [SCSI]     ffffa1864d6ed1d0  ffffa18624d64780  SCSI/READ (10)    ffffa1863a3eedb0  0000000000000000  200s
ffffa1864d96d570  [SCSI]     ffffa1864d9731d0  ffffa18624d85bd0  SCSI/READ (10)    ffffa1863aad73b0  0000000000000000  200s
ffffa1864d970870  [SCSI]     ffffa1864d6f31d0  ffffa18625ae9780  SCSI/READ (10)    ffffa1863a3f34d0  0000000000000000  200s
ffffa1864d96ba60  [SCSI]     ffffa1864d96bbd0  ffffa18624d66bd0  SCSI/READ (10)    ffffa1863aaaed60  0000000000000000  200s
ffffa1864d96ec40  [SCSI]     ffffa1864d9581d0  ffffa18625aef780  SCSI/READ (10)    ffffa1863a0219d0  0000000000000000  200s
ffffa1864d970010  [SCSI]     ffffa1864d7fb1d0  ffffa18624d78780  SCSI/WRITE (10)   ffffa1864d970f40  0000000000000000  200s
ffffa1864d962c40  [SCSI]     ffffa1864d9630e0  ffffa18625aee780  SCSI/WRITE (10)   ffffa1864d962b70  0000000000000000  200s
ffffa1864ce24570  [SCSI]     ffffa1864d96f1d0  ffffa18625ae7bd0  SCSI/READ (10)    ffffa1863a8a8a50  0000000000000000  200s
ffffa1864d963ca0  [SCSI]     ffffa1864d963e10  ffffa18624d67020  SCSI/READ (10)    ffffa18628c2d110  0000000000000000  200s
ffffa1864ce24940  [SCSI]     ffffa1864d9701d0  ffffa18625ae6780  SCSI/READ (10)    ffffa1862c3dd2b0  0000000000000000  200s
ffffa1864d9616f0  [SCSI]     ffffa1864d961860  ffffa18624ca5640  SCSI/READ (10)    ffffa1863a8a8c10  0000000000000000  200s
[...]

Cause

Unknown Citrix PVS defect.

Environment

• SEP 14.2 or higher

Resolution

This issue was resolved in Citrix Provisioning Services (PVS) 7.15.9, as part of the Citrix XenApp and XenDesktop 7.15 LTSR Cumulative Update 3 (CU3). Uninstalling any existing hotfixes and installing this version will resolve this issue.