iSCSI causing BSoD

[AndyNduffy]

I have a FreeNAS running on a HP microserver which is being used as a target for Windows Backup. A Server 2016 box is connecting over iSCSI and has been working for ages. Then yesterday, the Windows server crashed out of the blue (no pun intended). The server wouldn't boot whenever the LAN cable was plugged in. We tested another Windows server (an old 2012 server we were replacing with the new one) and that crashed as soon as we connected the LAN cable too. Both Windows servers had their iSCSI initiators configured to connect to FreeNAS and for 5 minutes during the day but were connected at the same time.
As soon as we turned off FreeNAS the servers were fine and have been since. Both Windows servers crashed with the error
"System thread exception not handled
What failed: NTFS.sys"

The only thing that has changed is the location of the FreeNAS box - it was moved to another part of the building and across another switch (I haven't checked, but may even been running over a 100Mb connection).
Has anyone else seen this? or has any advice?

 

[Ericloewe]

My first guess is a nasty timeout caused by poor performance that hits a weird, untested codepath in Windows.

 

[AndyNduffy]

My first guess is a nasty timeout caused by poor performance that hits a weird, untested codepath in Windows.

Yes, I thought must have been that. Is strange that it happens to 2 different vendors hardware. I did update the NIC firmware and drivers too - very strange.

 

[AndyNduffy]

Anyone have any ideas about this or any advice? I really need to use iSCSI as windows backup will not let you keep multiple backups like it will if it thinks it is a straight disk.

 

[DaveY]

I've been using iSCSI for years and never ran into this problem. That said, perhaps one of the iSCSI target is corrupted somehow. One thing you could try is to remove all the targets, create a new zvol and present it as the new target. Restart windows and see if the issue still occurs. If it doesn't, then one of the LUNs got corrupted. The BSOD error about NTFS.sys makes me suspect that may be the case.