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
[...]

Environment

• SEP 14.2 or higher

Cause

Unknown Citrix PVS defect.

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.