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Big issue with backup/restore

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areiners
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Big issue with backup/restore

I need help !

I'm using portable apps already a long time.

beside other applications, my complete private email history was on the stick.
Unfortunately the complete Thunderbird directory on the stick got corrupted yesterday.

Ok so I tried to restore my latest backup. The restore from portableapps took the backup file to restore it without reporting an error. Thought everything is fine. But it did not restore the Thunderbird (which I deleted on the stick before because it was corrupt).

When I tried to look at the zip file of the backup, I get the feedback from 7-zip that the zip file is invalid. Now I had a closer look at the file and see that the size is about 4GB which is - I think - the maximum file size for the filesystem.

I assume that when doing the backup, the zip file that was created got corrupt because of the size. Unfortunately portableapps did not report anything about this. the backup was done without reported error.

bad luck to me?

Now my questions:

1.) Can someone tell me how I can extract my emails from a eventually corrupt zip file?

2.) Is it possible that neither backup nor restore do any error checks in that direction? That can be seen as a big problem for portableapps !!!

Any help is appreciated (specially on how I can get my emails)

Thanks
Achim

John T. Haller
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Checks

Normally, 7-Zip doesn't generate the file properly if there is not enough space or it can't get all the files. It will error out and not produce the file. And the backup utility will present an error. I'd wager that 7-Zip can't detect the file size restriction and simply dies, leaving the file incomplete and, thus, corrupt. The backup utility then sees the file and thinks all is well, relying on 7-Zip to let it know there was an error.

I don't think anyone's tested the backup utility with the combination of (1) a large amount of files that will produce a >4gb 7z backup and (2) backing up to a drive that is formatted as FAT32. I know I haven't as all my drives are NTFS except for my smaller flash drives. And I know we didn't really consider this situation as we'd planned on people backing up their flash drives to their local PCs, which were assumed to be NTFS. I'll have to re-examine the code to determine if there is a way to properly address this (perhaps disallowing larger backups from being saved to FAT32 at all to avoid this possibility). This will be less of an issue as we've dropped support for Windows 95/98/Me; and Windows 2000 and up should be using NTFS. But it could still occur.

As for your case, I don't think there is anything we can do to retrieve your files. As the 7z archive is incomplete, it would seem that whatever is in it is what was restored. You may be able to undelete some of the files from the portable device using one of the undelete utilities out there, but some may be overwritten by the restore to the stick you already did. And if you didn't reformat, the current file system is probably unstable anyway (anytime you get large amounts of corruption on a drive, it's a huge red flag).

I wish there were something more I could suggest or do to get your data back, but I can't think of anything besides that. We call 7-Zip command line from the restore utility (as well as backup) and it looks like it is restoring what it can. 7-Zip GUI should be able to restore the files that are actually present in the archive, but will show an error for any that aren't. It is possible that some of the TB files are there but some are not, so you could try some various directories to see if they are there.

Does anyone else have any thoughts on how we can help Achim out?

Sometimes, the impossible can become possible, if you're awesome!

depp.jones
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Command line switch -v ?

Maybe it is possible to split the backup volume, by default or optional. That would eleminate this problem, but could possibly confuse some users with different suffixes. As 7zip is called per command line, adding a simple -v4g would do the job. If it is possible to determine the FS of the backup medium it could be chosen just in case (with a warning to the user?).
Fat32 is not so uncommon as some discussion went on awhile ago in the forums. It is accessible by most OS and does not produce as much wear to flash drives as NTFS. I even use Fat32 on my portable hd (not the best idea) but just because I still have to administer some very old computers and ntfs is so very slow with linux.

solanus
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Prevention

It would be a good idea to add in a setting/option to split backups at 4GB, which you should be able to do using the -v switch, and also an option to test the backup using the t switch.

I made this half-pony, half-monkey monster to please you.

solanus
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First, make copies of everything

Rule number one when you have a corrupted anything, is make copies of all the files, including the corrupted ones. That way, as you try this or that attempt to repair, you try it on the COPIES - if you mess stuff up, you still have the originals, and you can make another copy and try again.
So, make copies of the corrupted zip files, and start looking around for software that can help you recover.

A quick Google search got me this:
http://www.essentialdatatools.com/products/objectfixzip/

I've never used it, but it seems to be what you need.
There are likely to be more.

You may want to try several different, in case they each only recover a a part. That could maximize your recovery.

I made this half-pony, half-monkey monster to please you.

areiners
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StillInTrouble

Thanks for your hints.

My local filesystems are NTFS but obviously the network drive that I have connected to my router is not Sad This one holds the original backup.

Suggest really to correct this problem in portable apps !

To my restore problem:
I tried several tools I found on the internet (also the one mentioned by solanus), but the free ones did not help. One of them identified all directories and files successfully but the size of the file was then 0KB ...

If the commercial solutions really help - I do not know...

Now it's time to sleep (3:30 am in germany)

Achim

Best Regards
-Achim

pierrot
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Sorry, only solution for the future

Dear Achim,

since one or two years I am using a backup program for Emails (there exists also a portable version - not paf.). The name of the program is MailStore Home. A German product with a German/English Website. http://www.mailstore.com/en/

Since today I am more than content with this application. It is Freeware for private users.

Have a nice day
Peter

J Neutron
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Sorry

I'm very sorry to hear of your issue with your emails. As others have said, the situation may not be recoverable.

Suggestions for future solutions aren't much consolation, I know.

Something that everyone should take away from your experience is that backing up is only half of the data protection effort. Restoring is the other half. Backing up without periodically testing the restore places an awful lot of trust into the process.

Again, sorry to hear of your data loss.

neutron1132 (at) usa (dot) com

areiners
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IMAP vs. POP3 ?

Thanks to all of you for the information. Hope that this thread can help to improve the backup mechanism to prevent others from this bad luck.

Anyhow, I've given up with the recovery feeling that there is nothing to be recoverable any more in the zip...

Do you think using IMAP instead of POP3 is better to avoid such situations as the emails still reside on the server of the provider as well? Or what other kind of risks regarding the loss of mails do I have when using IMAP ?
( I'm thinking about using IMAP in future and unsure about the consequences and risks )

Achim

Best Regards
-Achim

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