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[ale] backup/restore mail from USB external drive

On 02/12/14 10:38, Brian Mathis wrote:
> 'rsync' is still a good option to copy files back.  It does not do a 
> full check of files unless they already exist on the destination side, 
> and even then it checks the date and filesize before doing a full 
> checksum.  If you use the options, you can preserve timestamps, view 
> progress, and easily stop/restart the copy if needed.  I'd use these 
> options: -av --progress --partial.  When copying between local disks, 
> it's just a version of 'cp' that gives you a lot more options.  Also, 
> I'd recommend running this inside of a 'screen' or 'tmux' session so 
> you can detach and leave it running, and/or protect against the 
> session getting dropped from the network.
> As far as step 5 goes, do you have enough physical space to add the 
> new drives next to the old ones?  Then you could make a partition for 
> the user data and stage it directly on the new drives.
> Incidentally, the point of a RAID is to be able to replace failing 
> drives without having to go through this process.  Is there any reason 
> why you can't just replace the failing drive and rebuild the existing 
> RAID to it?

We have one  failed disk and one  with failure predicted.  This is a 
Dell machine and they recommend rebuilding the whole thing when that 
happens. There is something called "puncturing" which is actually a good 
thing. It allows the RAID5 array to keep running even  if 1.5 disks have 

We just got unlucky and had two disks fail at the same time. Well, only 
one has actually failed.  The other just is in failure mode.
P.S. RAID is not a backup and you should always have some kind of backup 
job running to external media regardless of the health of the RAID.

Well, it's a mail server and nightly backups aren't good enough for this 
purpose. We don't want to restore from last night's backup and lose 8 - 
10 hours of mail.