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    Win Server 2012 R2 VM: repeated BSOD 0xD1 in xenvbd.sys (Citrix 8.1.0.130) - where to get VM Tools 9.2.3?

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    • H
      hrvojer
      last edited by

      Hi all,

      We have a production Windows Server 2012 R2 VM (SQL Server) that has crashed three times with the same bugcheck in xenvbd.sys. Looking for advice and for a safe download of the last 2012 R2-compatible tools.

      Environment

      • XCP-ng 7.6.0 (yes, we know it's EOL; [OPTIONAL - keep or delete: a host refresh/upgrade is already being planned]. Right now we need a stopgap for this VM.)
      • Storage: LVM over FC (HPE MSA 1040), multipath
      • VM: Windows Server 2012 R2 (build 9600.18505), 8 vCPU, 64 GB RAM (static, dynamic min = max)
      • PV drivers: Citrix xenvbd.sys 8.1.0.130 (old Citrix tools)

      Crashes (identical each time)

      • 2026-06-17, 2026-09-01, 2026-10-08
      • BUGCHECK 0xD1 DRIVER_IRQL_NOT_LESS_OR_EQUAL (0x18, 0x2, 0x1, xenvbd+0x8795)
      • Write to NULL+0x18: lock xadd dword ptr [rcx+18h],eax with rcx = 0
      • Stack (from MEMORY.DMP):
        nt!KiRetireDpcList -> nt!KiExecuteAllDpcs
        -> xenvbd+0xf464 -> xenvbd+0x6f55 -> xenvbd+0xfecb -> xenvbd+0x8795
        i.e. crash in a DPC, apparently in the I/O completion path.

      Context

      • The VM ran with 16 GB RAM from 2023-09 to 2026-02 with zero crashes (no restarts at all in ~29 months).
      • On 2026-02-06 RAM was raised to 64 GB (SQL max server memory 14 GB -> 48 GB).
      • First crash 4 months later; intervals between crashes so far: 131, 76, 37 days.
      • Host logs at the time of the last crash: no FC/SCSI/multipath errors. The only event on this VM's VDIs was one SMGC coalesce with a clean tapdisk pause/unpause about 12 minutes before the crash.

      Questions

      1. Is this a known xenvbd bug fixed in later versions (e.g. the 9.2.1 fix "A storage error can cause Windows VMs to crash", or the grant table exhaustion fix in 9.3.1)?
      2. A reply in the XSA-468 thread pointed to XenServer VM Tools 9.2.3 as the last version supporting 2012/2012 R2. Where can it be downloaded from an official source? downloads.xenserver.com only offers 9.6.0, and the same URL pattern for 9.2.3 returns 404.
      3. Could the RAM increase (16 -> 64 GB) plausibly trigger this with old xenvbd (grant tables, larger I/O)? Is there a workaround that doesn't require a driver update (e.g. a host-side setting)?

      We know 2012 R2 is EOL; we are looking for a safe stopgap.

      Thanks!

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