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We had a problem with our mailserver lately:

Setup:

  • Server with Raid 1
  • running XenServer
  • VM with Mailserver

What happend?

  • 1 disk failed
  • Raid-Controller locked the disks so nothing could be written to prevent data loss

And my question is, how does postfix handle this "can't write to disk" problem? There are no logs about that - because they also couldn't be written. Is postfix accepting mails? Does it queue the mails in memory, because it can't deliver them to mailbox or queue on disk? Do the mails get bounced?

cherubyn
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  • Most likely the connection fails and the sending server bounces the message back. – Halfgaar Jul 22 '13 at 08:12
  • It's very strange. With raid1 and one drive failed all should work as normal. What do you mean by "locked the disks"?. Filesystem in read only mode? – ALex_hha Jul 22 '13 at 08:15
  • yes, read only - actually I don't understand this behaviour of the raid controller and I'm not sure if this could be a kernel issue of xen (have a lot of strange system messages with I/O errors, but the raid controller says that the disks are fine after a reboot), but that's a different topic (with a lot more details) – cherubyn Jul 22 '13 at 08:24

1 Answers1

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Unfortunately, it wouldn't work at all. The sender will get bounce message. It would be something like

Jul 22 06:47:08 mail postfix/local[1405]: EB9CF12014D: to=<alex@example.net>, relay=local,
delay=0.4, delays=0.32/0.02/0/0.06, dsn=5.2.0, status=bounced (cannot update mailbox /var/spool/mail/alex for user alex. 
unable to create lock file /var/spool/mail/alex.lock: Read-only file system)".

As you can see dsn=5.2.0, that mean 5.XXX.XXX Permanent Failure

A permanent failure is one which is not likely to be resolved by resending the message in the current form. Some change to the message or the destination must be made for successful delivery.

You can find more at https://www.rfc-editor.org/rfc/rfc3463

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ALex_hha
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