Email delivery (sendmail->procmail->$HOME/mbox) with fallback

[Tim Alberts]

John Summerfield wrote:
>>> Use good hardware, good software (RHEL or a clone), IMAP and not 
>>> POP3, and use one of the reliable RAID (1, 4 or 5) choices for your 
>>> mail (and other critical data) storage.
>> Been using POP3 forever with no problems (except some Mac problems with 
>
> You do have a problem, your mail is scattered all over the place. imap 
> keeps it on the server.
That's a matter of perspective.  If they POP3 it off my server, it's 
their problem, not mine.  If I use IMAP, store it on the server, then if 
one server crashes, I switch to a backup with an old rsync and people 
get  mail marked as new that they already read, or get multiples of the 
same mail.  Meanwhile, email is lost on the original system.

>> Dovecot).  Have RAID1 software setup for years as well.  Keep getting 
>> drive failures and looking back into hardware RAID with high quality 
>> equipment (as mentioned before).
>>
>>>
>>> Even if a dodgy Fedora software update doesn't get you, you still 
>>> have to contend with frequent upgrades of the software.
>> Yes, I've dealt with 'dodgy' updates and config files being lost by 
>> auto updates, and bug fixes that mess things up that worked fine.  
>> For the price, it has been acceptable (at least to the people in 
>> charge of the purse strings).
>
> Price a problem? CentOS is free of charge. It also costs less.
OK, Fedora is free.  I'm talking about not paying licensing for Red Hat 
Enterprise, Suse Enterprise  etc.  Your saying CentOS is far more 
reliable than Fedora?  They're all Linux right?  Fedora is on the edge 
of development, I understand that, but that seems to be a good place, 
latest features, latest patches, latest security fixes.  Still get 
security patches and updates with CentOS right?  What are you saying is 
the difference?

>>>
>>> Note that RAID _can_ include a network block device (nbd or enhanced 
>>> nbd drivers), and drbd also provided RAID1 over a network, and is 
>>> tolerant of breaks in connectivity.
>>>
>>> note that LVM can provide hot backups.
>>
>>
>>>
>>> One trick I've hard of is to define a firewire drive (presumably USB 
>>> or other hotplug drive) would do as part of a mirror pair. Backup 
>>> goes something like this:
>>> Plug it in
>>> Resync.
>>> Detach (I don't recall the fine details here)
>>> Unplug.
>> Used removable drive trays for rsync backups without the RAID. Now we 
>> got backup systems that are rsync backed up and ready to run in 
>> failures.  However, any email that was delivered between the last 
>> rsync and the failure gets lost temporarily or permanently.  Hence my 
>> idea for NFS mount to quality RAID1
>
> NFS has its own problems. enbd and drdb are better than rsync.

NFS is not RAID or backup.  I'm not sure I've explained clearly what my 
idea is.  <explanation below>


>>
>>>
>>> Google for terms such as "reliable linux" "high availability linux" 
>>> "linux cluster" etc for more details.
>> Google'd and Yahoo'd...seen hundreds of ideas mostly based on 
>> heartbeat.  In fact I most recently was looking into Red Hat's Global 
>> File System and clustering:
>>
>> http://www.redhat.com/gfs/
>> http://www.redhat.com/cluster_suite/
>>
>> Trying to figure out how Red Hat is accomplishing these things with 
>> open source, or if they are adding their own proprietary background 
>> stuff.
>
> Look at CentOS. If it's in that (I believe it is) then it's OSS.
>>
>>
>>
>> All-in-all, fun discussion, but completely off topic from my original 
>> post and still doesn't answer my question.
>
> I'm more concerned with the underlying problem than with your proposed 
> solution.
What exactly do you see as the 'underlying problem'?
>
> Do you want the best solution?
>
Well that's just silly to ask now isn't it?




My idea is to use NFS to mount another file server that has a quality 
hardware RAID1 solution with hot swap drives ideally.  Then the primary 
mail application server runs a minimal drive to boot the OS and start 
the email program.  I NFS mount the file server for mail storage.  This 
way, if the primary mail server fails, a second application server 
(probably shared with the web or domain server) can takeover with the 
file system right where the primary mail server ended.