Mozy online backup: Reading the manual

Back in July of 2007 I blogged that Everybody likes Mozy -- except me. At the time, Mozy had gotten numerous accolades in the tech press*, but I found some down sides to the service.

Perhaps the biggest issue I had with Mozy was that if you deleted a file by mistake, they deleted backup copies of the file. Yes, they waited 30 days, but still, that wasn't a Defensive Computing scheme.  

The whole idea of unlimited backup storage for a fixed price seems wrong because it puts the customer and the backup company at odds with each other. The less space a customer uses, the more profitable it is for the company, thus it's motivated to store fewer files. In contrast, if you store files with a company that charges more money for more data, there is no motivation to delete anything.

I bring this up because Mozy recently gave up on their all-you-can-eat business model. They now charge customers based on the amount of data being stored. So I went back to revisit the issue of accidentally deleted files.

According to this question, What happens if I delete a file accidentally?, on Mozy's FAQ

When you delete or deselect a file it is removed from your backup configuration and marked for deletion on the Mozy servers. Mozy keeps a copy of that file in older backup sets just in case the deletion was accidental. Those older backup sets are kept for 30 days and then deleted.

Nothing has changed. Thirty one days after accidentally deleting a file, the backups are deleted.

In another FAQ, What happens if I delete a file marked for backup?, Mozy addresses purposeful deletions

If you delete a document and then run a backup, MozyHome assumes that you no longer need a backup copy of that document and marks the file to be removed. (We keep it for 30 days, just in case you change your mind.) After 30 days, the file is deleted from our servers and you are no longer able to get it back.

It's strange that a company charging by the gigabyte would be so aggressive in deleting files. An option not to replicate deletions would seem to be in everyone's best interest.  

Backblaze competes with Mozy and recently re-commited to offering unlimited storage space. They too, delete backups of deleted files after 30 days.

Same with Carbonite, another company offering unlimited storage for a fixed price. 

In fairness, there is no way for these companies to distinguish an intended file deletion from an accidental one or a file system error. But I can not recommend a backup scheme that does not offer an option to keep deleted files. Accidents happen, after all.

Mozy also lets you backup files that reside on an external hard drive, and that too comes with rules. The following is from their FAQ Does MozyHome support external drives?

If you have selected files from an external drive to be part of your regular backup and you unplug or turn off the drive while your backup is running, MozyHome detects that the files are gone and assumes that you no longer need them. Those files are then marked for deletion. After 30 days, the files are deleted from our servers and you are no longer able to get them back. However, if you reconnect the drive and run a back up, Mozy identifies the files, cancels the deletions and saves them in your backup set...

Backblaze works the same way:

Backblaze works best if you leave the external hard drive attached to your computer all the time. However, Backblaze will backup external USB and Firewire hard drives that are detached and re-attached as long as you remember to re-attach the hard drive at least once every 30 days.  If the drive is detached for more than 30 days, Backblaze interprets this as data that has been permanently deleted and securely deletes the copy from the Backblaze datacenter.

Then, there is the other side of the coin, where a customer wants to delete backed up files. For example, sensitive files might have been backed up accidentally.

It turns out that you can't delete files held by Mozy on your behalf. This is documented in an FAQ item How do I delete old backups?

Things get more complicated if a Mozy customer wants to save space. For example, an entry level user with one computer is now allowed to store up to 50 gigabytes of data for a fixed price. If they were storing 52 gigabytes back when it was all-you-can-eat, it's not hard to imagine that someone might want to delete some files to stay under the 50gb limit.

Easier said than done. According to Mozy:

 ...You most likely don't need to delete anything because your quota is based on your current backup configuration. Your previous backups don't count against you, and they don't take up any of your quota. To illustrate further: Let's say you have a 1000 MB quota. If you back up 300 MB of photos, then your available quota goes down to 700 MB, and you've got 300 MB of photos on our servers. The next day, you change your mind and want to back up spreadsheets instead. So you tell MozyHome to only back up spreadsheets and not photos, and it goes ahead and backs up 100 MB of spreadsheets. So now, your available quota is 900 MB because you are only backing up 100 MB of spreadsheets now. However, if you want to restore those photos, you still can for 30 days until the file versions expire.

Once any backup system is in place, monitoring it needs to be simple.

Windows antivirus programs are a great example of this. They typically have an icon in the system tray that changes appearance to indicate a problem. Microsoft Security Essentials uses a green icon when all is well and a red one when there is a problem. Avira's AntiVir uses an umbrella icon. When the umbrella is open you are protected, when it's closed you are not.

Mozy also has a system tray icon, but judging from their documentation it does not change its appearance to indicate a problem.

Their documentation (Why has MozyHome stopped performing backups?) mentions two configuration options in the Mozy software that prevent it from making backups and suggests that you check each item manually. If the software is configured to make backups, but there were errors, you are also directed to manually look for errors. 

Reading that article I couldn't help but notice that it was aimed at Windows users even though Mozy also supports Macs. In fact, my brief look through their on-line documentation, didn't turn up anything that spoke to OS X. And their 2x Protect feature, which adds on-site backups, is only available to Windows users.

The Mozy documentation was also missing dates. None of the articles indicated when they were written or last updated.

Finally, there is the issue of plans.

Mozy charges per computer and has different plans depending on whether data is being backed up from a personal computer or a server. Backblaze and Carbonite charge a fixed price per computer.

In contrast, the backup company that I use (which I will not mention as this is not an ad) charges by the gigabyte. The entire contract between us is X gigabytes for Y dollars. I can backup from any number of computers. 

Dropbox works like this too, which may explain why it is so popular. 

Update: Added note that Carbonite too deletes files after 30 days. Feb. 10, 2011

Update:  Somehow I stumbled across SugarSync. I have not used the service, but their website directly addresses the issue of keeping files permanently, thus offering protection from accidental deletions. Feb 11, 2011.

Update: As someone pointed out in the comments, Crashplan promises to never delete a file with their free service. But, with the free service your friends are storing your files, not Crashplan servers. Their website is very confusing on the features offered for free vs. paid. I need to look into this more... Feb 13, 2011  

Update:  According to a November 2010 review of Trend Micro SafeSync at that service too, deletes backups of a file 30 days after the file is deleted. So too, apparently, does Dropbox. February 4, 2011

*The good press continued, in May 2009, Mozy got an award from CNET

Backblaze explains their service in more detail:

The Backblaze service is designed to protect the files you care about. Thus, we will keep a remote backup of any file that exists on your computer. Just in case, Backblaze will even keep multiple versions of that file for up to 30 days. However, Backblaze is not designed as an additional storage system when you run out of space. So, please don’t try to upload your external hard drive to us and delete your data off your drive…or we will delete those files from our servers as well.

Copyright © 2011 IDG Communications, Inc.

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