Cbbackup: accumulative mode not working as documented?


#1

According to the manual, cbbackup --mode accu does a:

accu
Perform a cumulative incremental backup, which backs up all changes since the last full backup

However, it seems to backup all changes since the last full backup or previous accumulative backup.
Our intention was to run a weekly full backup and daily accumulative backups, so a restore would only require to restore the last full plus last accumulative backup. But the way it is working, an accumulative backup is effectively the same as incremental backups, when used in our backup scheme.
When first doing several incremental backups, an accumulated backup does include all changes contained in these incrementals, starting from the last full/accumulative backup.

Is this behaviour how it was intended to work?

(Coubase-server enterpise 3.0.1 on CentOS)


#2

Hi, The way accumulative backup is suppose to work is to take do back all the changes since last full-backup. For example -
On Sunday - cbbackup runs to backup all bucket data in the cluster to create a level 0 backup image
On Monday through Saturday - On each day from Monday through Saturday at midnight, cbbackup takes level 1 backup. It runs to back up all changes since Sunday level 0 backup.
So the Monday backup contains changes since Sunday, and Tuesday backup contains changes since Sunday and Monday and so forth.
Hope this helps. Let me know if this not the case in your deployment.
Thanks!


#3

Hi Anil,

I assume with ‘level 1 backup’ you mean accumulated?

It runs to back up all changes since Sunday level 0 backup.
So the Monday backup contains changes since Sunday, and Tuesday backup contains changes since Sunday and Monday and so forth

This is indeed what the manual suggests, but that is not how it behaves in CB E 3.0.1.

This is what I did:

  1. First I made a full backup
  2. Made some changes, say ‘changeset A’
  3. Run a cbbackup --mode accu: this contans changeset A
  4. Made some more changes (changeset B)
  5. Again run a cbbackup --mode accu: this should contain changesets A + B, but unfortunately it only contains changeset B.