backing up email / saving maildir on external hard drives

[Götz Reinicke - IT Koordinator]

Hi,

talking of rsync and compression is may be also a bit misleading.

On the destination there will be no compressed files if you transfer
with rsync! The transfere on the network by rsync might be compressed!


	/Götz


Am 09.08.15 um 18:33 schrieb Kevin Laurie:
> Dear Steve,
> Very valuable info. Appreciate it and will be careful when using terms.
> Actually I think I should just use rsync without compressing. The reason
> why I started compressing was because the GUI gave some errors when I was
> trying to copy then files.
> 
> I'll just rsync the data from my laptop HDD to my external drive(without
> compressing)
> 
> Thanks
> Kevin
> 
> On Sunday, August 9, 2015, Steve Litt <slitt at troubleshooters.com> wrote:
> 
>> On Sat, 8 Aug 2015 10:26:55 +0530
>> Kevin Laurie <superinterstellar at gmail.com <javascript:;>> wrote:
>>
>>> Hello,
>>> Yesterday I tried to back up a 40GB maildir .
>>> I tried to move the maildir from home to external HDD but failed.
>>
>> If you tried to *move* it it's an archive, not a backup. If you tried
>> to *copy* it, with the intent of keeping the original on the original
>> hard disk and using it further, and keeping today's copy on some other
>> media, *that's* a backup. I'm not trying to be pedantic, but there are
>> many distinctions between the two. Archives must be re-transferred
>> frequently: Backups merely need to be redone at intervals.
>>
>>> Decided then to compress it(which took several hours). Now changing
>>> the disk format from FAT to exFAT to allow the transfer for the large
>>> compressed file.
>>
>> Reading https://en.wikipedia.org/wiki/File_Allocation_Table#exFAT , I
>> personally wouldn't use exFAT. Regular FAT32 has a max filesize of
>> 2GB-1, which is 50 times the size of your whole uncompressed maildir.
>>
>>>
>>> How does one back up emails on a external drive?
>>> Some advice would be greatly appreciated.
>>
>> Check this out:
>>
>> ================================================
>> slitt at mydesq2:~$ df -h ~/mail/Maildir
>> Filesystem      Size  Used Avail Use% Mounted on
>> /dev/sdb8       116G   11G  100G  10% /home/slitt/mail/Maildir
>> slitt at mydesq2:~$
>> ================================================
>>
>> I don't have 40 GB, but * have 11, which is less than an order of
>> magnitude away. I just back up this puppy to my backup server with my
>> normal rsync based backup procedures, which you can read about here:
>>
>> * http://www.troubleshooters.com/lpm/200609/200609.htm
>>
>> * http://www.troubleshooters.com/linux/blu-ray-backup.htm
>>
>> * http://www.troubleshooters.com/lpm/201408/201408.htm
>>
>> The stuff about Blu-Ray is important only if you back up to blu-ray. I
>> like to keep some backups on write-once media, because kept in the
>> shade at reasonable temperatures and humidities, it tends to last
>> longer. And spinning disks that spend the majority of their time not
>> spinning tend to have problems.
>>
>> If this is a *backup*, I'd leave it uncompressed so you can take
>> incremental backups regularly. If it's an *archive*, meaning that the
>> data is immediately removed from your computer after copy, compression
>> might be in order, but you should make two copies and test them both
>> thoroughly before deleting the original, and you should test them every
>> couple months and if either goes bad, copy the other one to something
>> good. Archives are a PITA. For 40GB in these days of $150 2TB drives,
>> I'd keep the data intact, back it up, and when you outgrow your hard
>> drive, just get a bigger one.
>>
>> In other parts of this thread you ask how to separate backups from
>> different accounts from different computers. As far as accounts, I
>> think that Maildir directory structures would take care of that. As far
>> as different machines, just put the hostname at the front of each
>> destination directory.
>>
>>
>>
>> SteveT
>>
>> Steve Litt
>> July 2015 featured book: Rapid Learning for the 21st Century
>> http://www.troubleshooters.com/rl21
>>


-- 
Götz Reinicke
IT-Koordinator

Tel. +49 7141 969 82420
E-Mail goetz.reinicke at filmakademie.de

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