[CentOS] CentOS 7, rsync problem

Oddity: rsync *should* be recursing, and dealing with very large number of
files. It works, going from box a to box b. But when I try to back b up to
c, it fails, 100%, complaining of "out of hashtable space [sender]". I've
tried adding -r, and changing --delete to --delete-delay, and no joy.

All boxes are current, or fairly current, CentOS 7.

Anyone got any thoughts on the matter?

        mark

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