I primarily use dirvish for backups. I always include -AHSX in my configuration 
without issue. A single snapshot is about 600GB. When using rsync directly, I 
also have --numeric-ids --delete -ahPv. The only time I've run into a issue was 
when using -H to preserve hardlinks while duplicating an existing Dirvish 
backup drive to a new backup. The drive has many backups, some of them taken 
quarterly go back years. Without hardlinks, that copy would expand massively 
and certainly not fit in the destination drive, however, there were so many 
hardlinks that I think rsync ran out of memory and crashed.

I doubt preserving hardlinks during each backup saves much space, but doesn't 
cause any noticable issues/performance loss, but in the case of 
copying/rsyncing multiple backups from one drive to another, those hardlinks 
are invaluable for space saving, but will require much more RAM just due to the 
multiplied file count. Syncing 30 backups means potentially 30 times the number 
of files to track.

On June 21, 2018 8:50:37 AM PDT, Galen Seitz <[email protected]> wrote:
>Hi,
>
>A question for those of you using rsync for backup, particularly those 
>using dirvish or rsnapshot.  Are you using any of the following rsync 
>options to your rsync command?  I recently discovered that none of
>these 
>are present in my rsnapshot configuration.  I'm certain I want to add 
>--xattrs in order to preserve the selinux security context.  Adding 
>--acls seems harmless, even though I dont' think I'm using them.  I'm 
>tempted to add --sparse and --hard-links, but I'm concerned there might
>
>be some downsides of which I'm unaware.  Thoughts?
>
>         -A, --acls                  preserve ACLs (implies -p)
>         -X, --xattrs                preserve extended attributes
>         -S, --sparse                handle sparse files efficiently
>         -H, --hard-links            preserve hard links
>
>thanks,
>galen
>-- 
>Galen Seitz
>[email protected]
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-- 
Sent from my Nexus 4 with K-9 Mail. Please excuse my brevity.
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