[#1]

Hi,

I couldn't find any contact email address on the website so posted here instead!  Is there one?

I am trialling MozyPro for a client company and have been extremely impressed with the ease of use.  However, I have one technical question regarding the as advertised incremental file backup system Mozy uses.

I was informed that block level incremental backups were performed whereby only a file's changed 'blocks' were transferred to the online (original) file, not the whole file.  Since my client has a slow ADSL connection (c.200kbps upload) this feature will be needed!

However, I tested this feature out yesterday (on my ADSL connection) by creating a 10Mb Excel (2010) file and backing it up, it took 1m 56 secs at 687kbps - so transferring around 10Mb.

I then changed the Excel file locally by adding another 40kb to its size and backed it up again.  It took 2mins at 666hbps, suggesting that the full 10Mb was again transferred, NOT the incremental file size change of 40kb.

So,

Q1.    Is there something in the client setup that needs enabling to initiate block level backups?
Q2.    Does it only work on certain file types?
Q3.    Does it only work on certain file sizes?
Q4.    Is it's use linked to upload speed?

Thanks in advance.

Mike

[#2 · Accepted solution]

Mike136,

The "incremental backup" feature is a normal basic function of Mozy and does not need to be turned on in any options anywhere. 

I imagine that the variance in your backup time may have had to do with other network variables. 

Thanks!

James

[#3]

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Mike136 wrote:
~~~

Q1.    Is there something in the client setup that needs enabling to initiate block level backups?
Q2.    Does it only work on certain file types?
Q3.    Does it only work on certain file sizes?
Q4.    Is it's use linked to upload speed?

Thanks in advance.

Mike

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Good post/experiment.

A1. Nope

A2. Yes and no. It tries to work on all file types, but some apps (e.g. notepad) change files in a way so as to make them appear as though all of the file has changed (or so another posts says).

A3. There probably is a bottom end limit (e.g. anything under one megabyte - just back it up).

A4. I would not think so.

I would suggest repeating the test, but wait an hour or so between uploads (give the databases on the Mozy server time to sync stuff) Watch the network traffic graph inside Task Manager. You might want to change the colors:

That should give you a feel for 10MB vs 40kb without the problem that various parts of the backup process can take wildly different amounts of time from backup to backup.

[#4]

Hi Username_Issues,

Thanks for your answers that addressed all the questions directly.  I will re-try the back up of the 10Mb file, after adding another few kb.  I will also try a PST file that may be more approprite for block level back ups?

Although I appreciate your comments, It would be nice to have a definttive answer from someone workin at Mozy tech support.  Any takers out there??

Cheers

Mike

[#5]

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Mike136 wrote:........It would be nice to have a definttive answer from someone workin at Mozy tech support....

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Take a glance at this post.

[#6]

Username Issues answers are correct.

Waiting to backup to do the changes however doesn't matter. We run a kernel level driver that watches for file changes, and then during the backup just backs up the changes that way, doesn't matter what's on the server in that context.

The real question is, how did and what did you do to change the file? If a file changes 95% or more of it's blocks (I think that is what it is currently set to), then the entire file will backup. The other option is that the file was deleted and recreated to change, the program that changed it didn't just mod the file but re-wrote it.

You can also check the history and see if it really did upload the entire file.

[#7]

Hi Fryer,

Thanks for responding to this question.

In response to my method with the Excel 2010 workbook file:

Basically I created a 3 sheet workbook, with 2 sheets of many thousand cell numbers, totaling a file size of around 9.8Mb.  I saved this file to the online server using a non-scheduled backup via the Mozy Pro client. 

I then added numbers to the blank third sheet and re-saved the workbook (File_Save option).  The file size grew by about 40kb of data.

I ran the backup again and the whole file was uploaded, the history page in the settings menu shows 9.8+Mb transferred.

I repeated the addition of extra columns of data into the workbook, resaving and backing up.  Each time the full 9.8+Mb was transferred.

Unfortunately I do not know how MS Excel re-saves its workbooks to disc at a technical level.  Perhaps it completely re-writes the data?  Any ideas?

Mike

[#8]

I don't see your account, you changed your email recently?

I want to see the log for the backup, if you'll give me your email address for your backups I can take a look. PM me the email.

[#9]

I got your logs and took a look at the xlsx file you're talking about.

You're right, the entire file in this case is uploading. Comparing the file against itself though, with your small change there's 66.6% difference in the file, or two thirds of the file changes. With the small size of the file and how much it's changed, it's easier to upload the entire file than to just do the change.

[#10]

Hi Fryer,

Thanks for taking a look into those log files and reporting back.

The 66% change must mean that Excel effectively re-writes its file each time (rather inefficient) despite only a small % addition to its kb size.  That explains why Mozy takes it all up again.

I tested an Outlook.pst file earlier today and it appears that the block level increamental backup method is running on the subsequent file changes.  This is good since the Outlook data files are my main concern since they are changing daily and are up to 1 Gb each, so I didn't want them fully uploading each day, the client's upload speed is only 400kbps (max)!!

Thanks for your research

Mike