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Site Restoration

#21434 eXtract Wizard Extract division by zero

Posted in ‘Site restoration’
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Environment Information

PHP version
n/a
CMS Type
Other
CMS Version
n/a
Backup Tool Version
n/a
Kickstart version
n/a

Latest post by nicholas on Thursday, 13 November 2014 02:13 CST

toddwill
I have two full site backups done on a new site. The site was accidentally deleted yesterday and I am about to do a restore from yesterday's back ups. Before doing so, I wanted to test the backup. To do that I chose to use the eXtract Wizard. The back from yesterday gives the error "Division by zero" immediately upon asking for the extract (saying it is extracting "installation/README.html"). The one from a week ago does not. Two questions:
1) How can I address the div by zero?
2) In the extract from a week ago (which had no errors) I do not see any SQL files. Where are they?

This is very concerning.
I have attached the backup log for yesterday's file.

Cheers,
Todd
 Cheers,
Todd C. Williams

tampe125
Akeeba Staff
Hello Todd,

can you please try to use Kickstart on a local server?
Can you extract the archive in this way?

Davide Tampellini

Developer and Support Staff

🇮🇹Italian: native 🇬🇧English: good • 🕐 My time zone is Europe / Rome (UTC +1)
Please keep in mind my timezone and cultural differences when reading my replies. Thank you!

toddwill
The back up was still corrupt. Luckily it has the data files and I used the prior back up to restore the program files. The urgency has dropped as I have my site back. However, I do not test every backup I do (nor should I have to). It is VERY disconcerting to know that this backup was corrupt and I would like to know how to prevent (or at least detect it) in the future.

Odd that the bad backup that I get was after I paid for the product.

Cheers,
Todd
 Cheers,
Todd C. Williams

nicholas
Akeeba Staff
Manager
Dear Todd,

When you installed the software you were shown the following post-installation text:

I understand that an untested backup is as good as no backup at all

Even though this ought to be self-understood, we feel obliged to spell it out. You are supposed to periodically carry out test restorations of your backup archives to a subdomain, test server or a local development server. Backup archives may be corrupt, missing data (even an entire database or all of your site files in extreme cases!) or otherwise not working properly. Finding this out when your site is crashed is way too late. By clicking this box you understand that if you do not have a tested backup it will be outright impossible to provide any assistance to you regarding backup restoration. In any case we accept no liability whatsoever for the loss of data as per sections 15 and 16 of the GNU GPL license.


The reason of this text's existence is not a waiver of responsibility. Quite the opposite, we want you to be aware that an untested backup is as good as no backup at all for reasons beyond our control. Some reasons why your backup archive may be corrupt or incomplete follow.

Incomplete backups

  • The backup produced warnings about unreadable files / folders but you ignored them / didn't notice them.
  • You excluded files / folders and forgot about it (don't laugh, it's easier to happen than you might think).
  • You used a backup output directory which contains files you want to back up.
  • Database errors prevented backing up all database tables. We do issue warnings in this case.


Corrupt backups / unable to extract in full or in part

  • The backup failed but you tried restoring the incomplete backup archive anyway. It won't work.
  • The size of a file DECREASED while backing it up. If the file size increases there is no problem. This usually affects PHP error log files and we do try to exclude them using the common file name patterns found in 99% of web hosts.
  • A file disappears while backing it up. This also affects log and cache files, that's why we try to exclude them – as long as developers store them in the designated areas reserved by Joomla! for this kind of files.
  • You did not download all parts (e.g. .j01, .j02, ...) of a multipart backup archive.
  • You used the browser to download the backup archive even though we STRONGLY warned you against this in our video tutorials, quick start guide, documentation and even when you clicked the button to download the backup archive through the browser. Downloads through the browser are subject to badly written third party plugins, server configuration and browser configuration which are all beyond our control.
  • Your server or your FTP client resulted in an incomplete file transfer when downloading the backup archive parts. That's why we recommend a test extraction.


As you can see, we have taken all measures to protect you to the best possible extent from these issues:
  • Automatic filters which prevent issues from backing up temporary, error log and cache files
  • Issue warnings and errors when we detect something which may lead to an incomplete backup
  • Document all best practices to avoid corrupting your backups after they are taken and ensuring that they do work.


All of these conditions and precautions against them are shared between the Core (free) and Professional (paid) editions of our software. Paying us is irrelevant to any of that. I hope that the information above will help you ensure that you get good, tested backups all the time.

Nicholas K. Dionysopoulos

Lead Developer and Director

🇬🇷Greek: native 🇬🇧English: excellent 🇫🇷French: basic • 🕐 My time zone is Europe / Athens
Please keep in mind my timezone and cultural differences when reading my replies. Thank you!

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