Windows 2012 R2 BAD_POOL_CALLER Blue Screen of Death and iSCSI LUN on Synology NAS

I was called out today to look at a Windows 2012 R2 server that has been running happily since it was installed back in June of this year.  When it was installed, we also installed a Synology DS415+ NAS and 2 x 4TB drives which were mirrored to provide data protection.  The available space on the NAS was split into 2 volumes.  One volume was used for files that were needed locally / remotely and the other volume was used to present an iSCSI volume to the server as a local Hard Disk so that the backups were written onto the NAS.

Earlier in the month (7th October) I received several Improper Shutdown emails from the NAS as the power supply had fallen out of the back of the NAS because someone had knocked the power adapter that comes with it and that had caused the plug (4-pin DIN plug) to come out of the back of the NAS.

After the Improper Shutdowns, everything had been fine, backups were working to the NAS and all was well.

Around 3:00pm on the 15th October, our office received a call advising us that the server had Blue-Screened with a BAD_POOL_CALLER blue screen of death and could we help to get it working again.  Numerous options were tried by our support staff to get the server back up and running again but all proved fruitless and so I was asked to attend site 1st thing in the morning.

When I arrived, I noticed that the NAS was not working properly (the power light was on but no LAN lights), so I switched it off.  I then went to look at the server which had been left in Safe Mode overnight.  Digging around I couldn’t see anything screamingly obvious as to why the server had suddenly died.  There had been no Windows Updates, no system changes, no power issues, nothing that I found using Google seemed to fit the issue I was having, so I gave the server a reboot and randomly it rebooted cleanly.  I logged in to the server and it seemed totally happy.

After leaving it running for a few minutes, I decided that if that server was fine, the NAS should be switched back on again so the users could access the files on the NAS.  After switching on the NAS, I sat down to drink a cup of tea and discuss how weird it was that the server booted happily after failing to do so numerous times the night before.  A few minutes later, the server fans went into turbo mode and I got that sinking feeling that the server had crashed again and it indeed had.

So – I switched off the NAS, rebooted the server, which booted happily, removed the iSCSI connections to the NAS, powered on the NAS and everything was working happily again.  At some point in the very near future, I will zap the volume, zap the iSCSI LUN / Target on the NAS, re-create them and then re-connect the server back up and hope that the problem goes away.

So – if you receive a BAD_POOL_CALLER Blue Screen of Death error on a Windows Server using an iSCSI volume on a NAS, then it may well be the iSCSI volume that caused the problem and you will hopefully know how to fix it.