Rich/rerat said:
I know that Acronis True Image, will create full backups, even if you set
the program to make differential or incremental backups. This occurs if the
drive has been defrag between backup sessions, because of files being moved
during the defrag process. Acronis TI compares the location of files in the
backup file, to the location of the drive. If there is a difference, it will
create a new full backup of the drive.
I know that from personal experience with Acronis TI, I have never used the
MS backup program. But it may act the same way.HTH
The reason you get a full backup when running an incremental or
differential backup job with ATI after doing a volume defrag is that you
have moved around a lot of the clusters in the file system. The files
have been so much rearranged that a defrag+backup gives you a full
backup. Actually you don't get exactly the same as a full backup. You
get a huge incremental that accounts for all the movement of files due
to the defrag. You've obviated the advantage of a small file size for
an incremental if it has to record all those changes in the file system.
That's why you have to carefully schedule a defrag job in Task
Scheduler. I scheduled ATI to do a full backup on Monday morning at 5AM
and incremental backups at 5AM on other days. To make sure the
incrementals are really incrementals, the defrag job is scheduled to run
at 2AM on Monday morning - before the ATI full backup job. That defrag
job is also scheduled to terminate at 3 hours to prevent it from running
at the same time as the full backup. I could schedule an incremental
backup on Monday at 5AM which would become a full backup due to the
prior defrag at 2AM but it's easier to keep track of what backup job did
what according to the name of the backup job. An incremental backup
just records the changes but a defrag generates a LOT of changes.
http://kb.acronis.com/content/2712
http://kb.acronis.com/content/1536
As to the OP's original concern regarding file space management (in
whatever partition the backup files are stored), Acronis TrueImage will
perform automatic management of backup files (regarding retention and
expiring/deleting of old backups) *if* you use their hidden partition
for saving backups (aka "Acronis SecureZone"). When you use that then
they will automatically manage the old backups to delete as many as
necessary to make room for the current backup. If you don't use their
SecureZone, you're stuck doing the manual management: when the free disk
space is insufficient where you are saving the current backup, the
backup fails and you have to manually delete the old backup files to
make room. If you are doing full+incremental or full+differential
backup cycles then you need to delete the old incrementals or old
differentials along with the old full backups (since they incr or diffs
have no use without the fulls).
I trialed Paragon's Backup & Recovery 2011 Advanced. (Actually,
"Advanced", free edition, has been crippled by removing the cyclic
backups where you could base differentials off the last prior full
backup, so Advanced has less features than the non-Advanced 2010
version). For that product, you also have to use their hidden partition
(aka Backup Capsule) to store backup files to take advantage of their
automatic file management.
There is no automatic management of backup files with the Microsoft NT
Backup program. Once you fill up a partition with backup files, there
will be no more space to store more backups. You have to go into the
partition to delete the old full+incr/diff backup files to make room for
newer backups. Unless you use the hidden partition with ATI or free
Paragon, you also don't get automatic file management (I don't recall if
the paid version of Paragon includes automatic file management outside
their "Backup Capsule" hidden partition).
