sorry corrections: For this test I created a 40GB lvm volume group with /dev/sdb and /dev/sdc then a 40GB LV then a 60GB VDO vol (for testing purposes) vdostats --verbose /dev/mapper/vdoas | grep -B6 'saving percent' output from just created vdoas [root at localhost ~]# vdostats --verbose /dev/mapper/vdoas | grep -B6 'saving percent' physical blocks : 10483712 logical blocks : 15728640 1K-blocks : 41934848 1K-blocks used : 4212024 1K-blocks available : 37722824 used percent : 10 saving percent : 99 [root at localhost ~]# FIRST copy CentOS-7-x86_64-Minimal-2003.iso (1.1G) to vdoas from source outside vdo volume [root at localhost ~]# vdostats --verbose /dev/mapper/vdoas | grep -B6 'saving percent' 1K-blocks used : 4721348 1K-blocks available : 37213500 used percent : 11 saving percent : 9 SECOND copy CentOS-7-x86_64-Minimal-2003.iso (1.1G) to vdoas form source outside vdo volume #cp /root/CentOS-7-x86_64-Minimal-2003.iso /mnt/vdomounts/CentOS-7-x86_64-Minimal-2003-version2.iso 1K-blocks used : 5239012 1K-blocks available : 36695836 used percent : 12 saving percent : 52 THIRD copy CentOS-7-x86_64-Minimal-2003.iso (1.1G) to vdoas form inside vdo volume to inside vdo volume 1K-blocks used : 5248060 1K-blocks available : 36686788 used percent : 12 saving percent : 67 Then I did this a total of 9 more times to have 10 ISOs copied. Total data copied 10.6GB. Do note this: When using DF, it will show the VDO size, in my case 60G when using vdostats it will show the size of the LV, in my case 40G Remeber dedupe AND compression are enabled. The df -hT output shows the logical space occupied by these iso files as seen by the filesystem on the VDO volume. Since VDO manages a logical to physical block map, df sees logical space consumed according to the file system that resides on top of the VDO volume. vdostats --hu is viewing the physical block device as managed by VDO. Physically a single .ISO image is residing on the disk, but logically the file system thinks there are 10 copies, occupying 10.6GB. So at the end I have 10 .ISOs of 1086 1MB blocks (total 10860 1MB blocks) that yield these results: 1K-blocks used : 5248212 1K-blocks available : 36686636 used percent : 12 saving percent : 89 So at the end it is using 5248212 1K blocks minus 4212024 initial used 1K blocks, gives (5248212 - 4212024) = 1036188 1K blocks / 1024 = about 1012MB total. Hope this helps understanding where the space goes. BTW: Testing system is CentOS Linux release 7.8.2003 stock. with only "yum install vdo kmod-kvdo" History of commands: [root at localhost vdomounts]# history 2 pvcreate /dev/sdb 3 pvcreate /dev/sdc 8 vgcreate -v -A y vgvol01 /dev/sdb /dev/sdc 9 vgdisplay 13 lvcreate -l 100%FREE -n lvvdo01 vgvol01 14 yum install vdo kmod-kvdo 18 vdo create --name=vdoas --device=/dev/vgvol01/lvvdo01 --vdoLogicalSize=60G --writePolicy=async 19 mkfs.xfs -K /dev/mapper/vdoas 20 ls /mnt 21 mkdir /mnt/vdomounts 22 mount /dev/mapper/vdoas /mnt//vdomounts/ 26 vdostats --verbose /dev/mapper/vdoas | grep -B6 'saving percent' 28 cp /root/CentOS-7-x86_64-Minimal-2003.iso /mnt/vdomounts/ -vvv 29 vdostats --verbose /dev/mapper/vdoas | grep -B6 'saving percent' 30 cp /root/CentOS-7-x86_64-Minimal-2003.iso /mnt/vdomounts/CentOS-7-x86_64-Minimal-2003-version2.iso 31 vdostats --verbose /dev/mapper/vdoas | grep -B6 'saving percent' 33 cd /mnt/vdomounts/ 35 cp CentOS-7-x86_64-Minimal-2003-version2.iso ./CentOS-7-x86_64-Minimal-2003-version3.iso 36 vdostats --verbose /dev/mapper/vdoas | grep -B6 'saving percent' 37 df 39 vdostats --hu 40 ls -l --block-size=1MB /root/CentOS-7-x86_64-Minimal-2003.iso 41 df -hT 42 vdo status | grep Dedupl 43 vdostats --hu 44 vdostats 48 cp CentOS-7-x86_64-Minimal-2003-version2.iso ./CentOS-7-x86_64-Minimal-2003-version4.iso 49 cp CentOS-7-x86_64-Minimal-2003-version2.iso ./CentOS-7-x86_64-Minimal-2003-version5.iso 50 cp CentOS-7-x86_64-Minimal-2003-version2.iso ./CentOS-7-x86_64-Minimal-2003-version6.iso 51 cp CentOS-7-x86_64-Minimal-2003-version2.iso ./CentOS-7-x86_64-Minimal-2003-version7.iso 52 cp CentOS-7-x86_64-Minimal-2003-version2.iso ./CentOS-7-x86_64-Minimal-2003-version8.iso 53 cp CentOS-7-x86_64-Minimal-2003-version2.iso ./CentOS-7-x86_64-Minimal-2003-version9.iso 54 df -hT 55 ls -l --block-size=1MB 56 vdostats --hu 57 df -hT 58 df 59 vdostats --hu 60 vdostats 61 vdostats --verbose /dev/mapper/vdoas | grep -B6 'saving percent' 62 cat /etc/centos-release 63 history [root at localhost vdomounts]# On Sat, May 2, 2020 at 10:07 PM Erick Perez - Quadrian Enterprises < eperez at quadrianweb.com> wrote: > 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 > > -- --------------------- Erick Perez Quadrian Enterprises S.A. - Panama, Republica de Panama Skype chat: eaperezh WhatsApp IM: +507-6675-5083 ---------------------