Re: Odd behaviour of two identical ZFS servers mirroring via rsync

, Nov 11, 2022 at 8:42 PM andy thomas <andy@time-domain.co.uk> wrote:

> I have two identical servers, called clustor2 and clustor-backup, each
> with a ZFS RAIDZ-1 pool containing 9 SAS hard disks plus one spare and two
> SSDs for the ZIL and ARC functions. clustor2 stores user data from a
> HPC while clustor2-backup uses rsync to mirrors all the data from clustor2
> every 24 hours.
>
> However, the disk usage on the mirror server is considerably more than on
> the other server - attached is a screenshot showing the two servers side
> by side, with the mirror server on the right, and displaying the contents
> of the same subdirectory choen at random (named 'ratio_10.0' in this
> instance); as you can see, the sizes of the files within each of the
> folders are identical but 'du' reports very different
> space usages for each folder and 'zpool list' also reports a significant
> difference in ZFS pool size.
>
> I'm not sure if this is relevant but both servers have ZFS pools with no
> compression although lz4 compression is enabled on the ZFS filesystems &
> both run FreeBSD 11.3 with ZFS version 5.
>
> Perhaps using zfs send/receive instead of rsync for mirroring might solve
> this disparity?
>
> Thanks in advance for any suggestions,
>
> Andy




Your question I am understanding the following points .



I am using  rsync  in Fedora Linux .

There are  parameters of  rsync  such as

 --delete

to delete files from the destination drive when they do not exist in the
source drive .


Please carefully scan  rsync  parameters and use suitable ones for your
application .


If  a parameter like  --delete  is not used , rsync  copies new files from
the source drive and
it does not delete any files from the destination drive .


With my best wishes for all .


Mehmet Erol Sanliturk