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 [...]
Unknown Citrix PVS defect.
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.