My two cents: 1- Do you have an encrypted filesystem on top of VDO? If yes, you will see no benefit from dedupe. 2- can you post the stats of vdostats –verbose /dev/mapper/xxxxx (replace with your device) you can do something like: "vdostats -verbose /dev/mapper/xxxxxxxx | grep -B6 'save percentage' On Sat, May 2, 2020 at 9:54 PM david <david at daku.org> wrote: > Folks > > I'm looking for a solution for backups because ZFS has failed on me > too many times. In my environment, I have a large amount of data > (around 2tb) that I periodically back up. I keep the last 5 > "snapshots". I use rsync so that when I overwrite the oldest backup, > most of the data is already there and the backup completes quickly, > because only a small number of files have actually changed. > > Because of this low change rate, I have used ZFS with its > deduplication feature to store the data. I started using a Centos-6 > installation, and upgraded years ago to Centos7. Centos 8 is on my > agenda. However, I've had several data-loss events with ZFS where > because of a combination of errors and/or mistakes, the entire store > was lost. I've also noticed that ZFS is maintained separately from > Centos. At this moment, the Centos 8 update causes ZFS to > fail. Looking for an alternate, I'm trying VDO. > > In the VDO installation, I created a logical volume containing two > hard-drives, and defined VDO on top of that logical volume. It > appears to be running, yet I find the deduplication numbers don't > pass the smell test. I would expect that if the logical volume > contains three copies of essentially identical data, I should see > deduplication numbers close to 3.00, but instead I'm seeing numbers > like 1.15. I compute the compression number as follows: > Use df and extract the value for "1k blocks used" from the third column > use vdostats --verbose and extract the number titled "1K-blocks used" > > Divide the first by the second. > > Can you provide any advice on my use of ZFS or VDO without telling me > that I should be doing backups differently? > > Thanks > > David > > _______________________________________________ > CentOS mailing list > CentOS at centos.org > https://lists.centos.org/mailman/listinfo/centos > -- --------------------- Erick Perez