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@troubleshooters.com wrote:

On Sat, 8 Aug 2015 10:26:55 +0530 Kevin Laurie javascript:;> wrote:

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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@mydesq2:~$ df -h ~/mail/Maildir Filesystem Size Used Avail Use% Mounted on /dev/sdb8 116G 11G 100G 10% /home/slitt/mail/Maildir slitt@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