dovecot crash with Panic: file istream-header-filter.c: line 663

[Gerald Galster]

>>> 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