still having this problem.
I just started a backup (client side) for a User.
Running top I get repquota for some minutes and then
16311 nobody    20   0   53024  16592   2644 R 100.0  0.0   8:21.54 directadmin
# lsof -p 16311
COMMAND     PID   USER   FD   TYPE   DEVICE SIZE/OFF      NODE NAME
directadm 16311 nobody  cwd    DIR      9,2     4096  93194993 /usr/local/directadmin
directadm 16311 nobody  rtd    DIR      9,2     4096         2 /
directadm 16311 nobody  txt    REG      9,2  8809304  93195240 /usr/local/directadmin/directadmin
directadm 16311 nobody  mem    REG      9,2   555888  93195460 /usr/lib64/libfreeblpriv3.so
directadm 16311 nobody  mem    REG      9,2    61624  93194453 /usr/lib64/libnss_files-2.17.so
directadm 16311 nobody  mem    REG      9,2    11392  93192968 /usr/lib64/libfreebl3.so
directadm 16311 nobody  mem    REG      9,2  2156160  93194067 /usr/lib64/libc-2.17.so
directadm 16311 nobody  mem    REG      9,2    88776  93195467 /usr/lib64/libgcc_s-4.8.5-20150702.so.1
directadm 16311 nobody  mem    REG      9,2  1137024  93194370 /usr/lib64/libm-2.17.so
directadm 16311 nobody  mem    REG      9,2   991616  93194043 /usr/lib64/libstdc++.so.6.0.19
directadm 16311 nobody  mem    REG      9,2    43776  93194456 /usr/lib64/librt-2.17.so
directadm 16311 nobody  mem    REG      9,2   142232  93194333 /usr/lib64/libpthread-2.17.so
directadm 16311 nobody  mem    REG      9,2   105824  93194455 /usr/lib64/libresolv-2.17.so
directadm 16311 nobody  mem    REG      9,2    19288  93194348 /usr/lib64/libdl-2.17.so
directadm 16311 nobody  mem    REG      9,2    90248  93194218 /usr/lib64/libz.so.1.2.7
directadm 16311 nobody  mem    REG      9,2    40664  93194246 /usr/lib64/libcrypt-2.17.so
directadm 16311 nobody  mem    REG      9,2   163400  93192764 /usr/lib64/ld-2.17.so
directadm 16311 nobody    0r   CHR      1,3      0t0      1028 /dev/null
directadm 16311 nobody    1u   CHR      1,3      0t0      1028 /dev/null
directadm 16311 nobody    2u   CHR      1,3      0t0      1028 /dev/null
directadm 16311 nobody    3r   REG      9,3 20389908 142868483 /home/tmp/quota-dump.tHqhnW7aZONDBhzk5NharUkCXmQfQkVH1Lyns6NRSledQdOVz33qVl20YQdwB8DA.greotleb
directadm 16311 nobody    4u  IPv6 17120929      0t0       TCP lnx8.ormag.net:EtherNet/IP-1->host228-252-dynamic.233-95-r.retail.telecomitalia.it:56379 (ESTABLISHED)