experiments with sort_key and affinity

4+2x2

1 sdb1
1 sdb11
/srv/node3/sdb11/objects-1/275/9f7/44f54ec73ee6726f26dcfd90d3ae59f7/1486081862.39258#2#d.data
1 sdb13
/srv/node1/sdb13/objects-1/275/9f7/44f54ec73ee6726f26dcfd90d3ae59f7/1486081862.39258#4#d.data
1 sdb15
1 sdb3
/srv/node3/sdb3/objects-1/275/9f7/44f54ec73ee6726f26dcfd90d3ae59f7/1486081862.39258#2#d.data
1 sdb5
/srv/node1/sdb5/objects-1/275/9f7/44f54ec73ee6726f26dcfd90d3ae59f7/1486081862.39258#4#d.data
1 sdb7
/srv/node3/sdb7/objects-1/275/9f7/44f54ec73ee6726f26dcfd90d3ae59f7/1486081862.39258#0#d.data
1 sdb9
/srv/node1/sdb9/objects-1/275/9f7/44f54ec73ee6726f26dcfd90d3ae59f7/1486081862.39258#0#d.data

2 sdb10
/srv/node2/sdb10/objects-1/275/9f7/44f54ec73ee6726f26dcfd90d3ae59f7/1486081862.39258#5#d.data
2 sdb12
/srv/node4/sdb12/objects-1/275/9f7/44f54ec73ee6726f26dcfd90d3ae59f7/1486081862.39258#1#d.data
2 sdb14
2 sdb16
/srv/node4/sdb16/objects-1/275/9f7/44f54ec73ee6726f26dcfd90d3ae59f7/1486081862.39258#5#d.data
2 sdb2
/srv/node2/sdb2/objects-1/275/9f7/44f54ec73ee6726f26dcfd90d3ae59f7/1486081862.39258#1#d.data
2 sdb4
/srv/node4/sdb4/objects-1/275/9f7/44f54ec73ee6726f26dcfd90d3ae59f7/1486081862.39258#3#d.data
2 sdb6
2 sdb8
/srv/node4/sdb8/objects-1/275/9f7/44f54ec73ee6726f26dcfd90d3ae59f7/1486081862.39258#3#d.data


I made 10 GET requests:

for i in {1..10}; do swift download ec-test swift.tar.gz -o deleteme; done


I checked how many backend requests went to each disk:

grep 275/AUTH_test/ec-test/swift.tar.gz /var/log/syslog | grep object | grep proxy | awk '{print $12}' | cut -d / -f 2 | sort | uniq -c 


read_affinity = r1=100 (with sort_key)
     10 sdb10
      1 sdb11
     10 sdb12
      4 sdb13
     10 sdb8
      5 sdb9
total request 40

read_affinity = r2=100 (with sort_key)
      4 sdb10
     10 sdb11
      2 sdb12
     10 sdb13
      4 sdb8
     10 sdb9
total request 40

read_affinity = r1=100 (no sort_key)
     10 sdb10
      3 sdb11
     10 sdb12
      3 sdb13
     10 sdb16
     10 sdb2
     10 sdb4
      1 sdb7
     10 sdb8
      3 sdb9
total request 70

read_affinity = r2=100 (no sort_key)
      1 sdb10
     10 sdb11
      2 sdb12
     10 sdb13
      1 sdb16
     10 sdb3
      3 sdb4
     10 sdb5
     10 sdb7
      3 sdb8
     10 sdb9
total request 70

shuffle (no sort_key)
      2 sdb10
      6 sdb11
      5 sdb12
      6 sdb13
      5 sdb16
      3 sdb2
      6 sdb3
      2 sdb4
      2 sdb5
      2 sdb7
      4 sdb8
      2 sdb9
totaly request = 45

shuffle (with sort_key)
      6 sdb10
      6 sdb11
      8 sdb12
      6 sdb13
      7 sdb8
      7 sdb9
total request = 40