After the above, it's no longer crashing, and my email client's "pending operations" have cleared.
Does your server use ECC memory and if so, are there any errors logged (bitflip, ...)?
Best regards, Gerald
I don't have the logs from that time them nor do I see any hardware / memory errors.
I also haven't had any other odd failures.
But how can I tell if I have ECC memory or not?
You could install dmidecode and search for ECC (not L1/L2 cpu cache), e.g.
Physical Memory Array Location: System Board Or Motherboard Use: System Memory Error Correction Type: Multi-bit ECC Maximum Capacity: 128 GB Error Information Handle: 0x0008 Number Of Devices: 4
It happens rarely but without ECC those errors often go without notice.
With ECC dmesg/kernel log might show warnings like
kernel: [Hardware Error]: Unified Memory Controller Ext. Error Code: 0, DRAM ECC error. kernel: EDAC MC0: 1 CE Cannot decode normalized address on mc#0csrow#2channel#1 ... kernel: [Hardware Error]: cache level: L3/GEN, tx: GEN, mem-tx: RD kernel: core: [Hardware Error]: Machine check events logged kernel: [Hardware Error]: Corrected error, no action required.
Best regards, Gerald