Large incremental backups
Does incremental backup actually backup an entire file if the file has changed or does it only backup the part of the file that has changed? For example, my Outlook file is normally between 600MB and 1GB. Does this mean that my incremental backups will always be AT LEAST this big?
TIA
I suppose this isn't that hard to test myself. I'm going to "touch" a large file after tonight's incremental backup and then manually run another incremental to see what happens.
I did a full backup and then shut down the computer. 6 hours later, I turned on my computer and "touched" Outlook. I then did an incremental and this incremental is 330MB. My whole Outlook file is 650MB so I don't think I received 330MB of email in 6 hours. Why is my incremental backup so big?
Help!
Fiat Slug, I'm no expert, but my suggestion, and somebody please correct me if I'm way off base- but, the backup program isn't looking for changes in files - it's looking for sectors that have changed- and it's possible during that during that short time period your computer did a partial defrag? Or for some reason, it moved sectors around? And incremental of 330 MB doesn't really seem that big. Your system may also have done some updates or "clean up" without you knowing? I believe computers are always doing background stuff that we never know about and it can change 330 MB worth of sectors in a flash. The swap file can be huge and that changes constantly- but I think by default that's not backed up- it should be listed in the file types to not back up.
Joe
Fiat Slug, when you put yor 650 MByte outlook file into a zip archive you should end up with an archive file of appr. 330 MByte size. I think, ATI does a similar compression, and that´s why you end up with a 330 MByte incremental backup.
Does an expert agree to my thoughts?
Joseph Zorzin, I don't think defrag is the culprit. The drive was last "optimized" 4 days ago and this test was performed yesterday. Also, this is an SSD. Swapfiles are not backed up as I've not changed that setting from the default. Furthermore, the total uptime between the full and the incremental was maybe 15 minutes so 330 MB after 15 minutes is pretty big.
Berti, good suggestion. As a test, I compressed my 650MB outlook file and it came to about 570MB.
BTW, a typical daily incremental for me is anywhere from 1.5GB to 10GB. What got me curious is the fact that there's doesn't seem to be any correlation between the sizes of my incrementals and how man files I actually change in a day.
Fiat Slug, have you ever tried to make differential backups instead of incremental?
Anyhow - I think we are trying to do a sort of reverse engineering of ATI2015 and I´m afraid, that doen´t make too much sense.
Someone of Acronis staff should be able to explain these issues or the philosophy behind.
I still think, even in a short time, the OS must have changed many sectors. Since you have an SSD, which are very fast, I bet the OS could have changed several hundred MBs very quickly, doing who knows what- some hidden clean up work? Some downloads of your AV program? There's a lot going on all the time without us knowing about. So, even with one knew email, ATI might see a lot of sectors changing.
As Berti suggests- it would be nice if an Acronis tech or one of the IT pros here were to explain this- I'm sure there's a logical reason.
Joe
I suppose that it is possible that an update happened in the background during those 15 minutes of uptime. I will repeat the test again tonight and see what happens.
It might also be interesting to try a similar experiment by modifying a Word file or any other file type.
Joe
It might also be interesting to try a similar experiment by modifying a Word file or any other file type.
Joe
It might also be interesting to try a similar experiment by modifying a Word file or any other file type.
Joe
hmmm.... just thought of another experiment- do a full backup, then leave your computer on for several minutes without doing anything- then do either an incremental or differential. Without doing anything, some sectors will change and you'll be able to count them- if you know the size of the sectors. Most of the files that change will probably be hidden system files.
I might try this when I get a chance.
Joe
Windows is constantly shuffling files around in the background. I have both system restore and defrag turned OFF and make daily incrementals. Sometimes I might not even change anything on the PC and yet the files are always around 0.3 to 0.5gb region as a minimum.
This image shows this weeks incrementals with the base image at the top. Yesterdays incremental was large because I installed 9 updates (W8.1) then did a reboot and followed that by a full disk clean (including system files cleanup), then another reboot, then a defrag, then a final reboot, and then a backup.
