On sf-001 and sf-002 with disk platters:

# XXX does this survive reboot ? XXX
echo 65536 > /sys/block/sdb/queue/nr_requests
echo 65536 > /sys/block/sdc/queue/nr_requests
echo 65536 > /sys/block/sdd/queue/nr_requests

echo 8192 > /sys/block/sdb/queue/read_ahead_kb
echo 8192 > /sys/block/sdc/queue/read_ahead_kb
echo 8192 > /sys/block/sdd/queue/read_ahead_kb