Further testing has shown that this can occur with just a single heat user performing snapshot / restore operations. Also tested with *just* create_snapshot operations and memory usage still appears significant, though less than when restore operations are also used in testing. top - 17:09:20 up 2:26, 2 users, load average: 0.13, 0.23, 0.22 Tasks: 371 total, 3 running, 368 sleeping, 0 stopped, 0 zombie %Cpu(s): 1.1 us, 0.3 sy, 0.0 ni, 98.0 id, 0.5 wa, 0.0 hi, 0.0 si, 0.0 st KiB Mem: 37066820 total, 20059448 used, 17007372 free, 192664 buffers KiB Swap: 37738492 total, 68 used, 37738424 free. 13992420 cached Mem PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 24980 libvirt+ 20 0 3917968 989.2m 9424 S 0.0 2.7 0:19.24 qemu-system-x86 2179 rabbitmq 20 0 2381912 172444 2516 S 1.3 0.5 2:22.75 beam.smp 10769 stack 20 0 339112 143740 3896 S 0.0 0.4 0:12.13 nova-api 10766 stack 20 0 339260 143668 3872 S 0.0 0.4 0:12.47 nova-api 1475 root 20 0 422924 142980 1184 S 0.0 0.4 0:01.05 zfs-fuse 10767 stack 20 0 338632 142916 3896 S 0.0 0.4 0:11.58 nova-api 10768 stack 20 0 337696 142312 3880 S 0.0 0.4 0:10.94 nova-api 8310 mysql 20 0 4165360 117316 7964 S 0.0 0.3 1:03.81 mysqld 10918 stack 20 0 276152 88792 3756 S 0.0 0.2 0:22.74 nova-conductor 10915 stack 20 0 275072 87812 3752 S 0.0 0.2 0:23.10 nova-conductor 10749 stack 20 0 190252 87764 5536 S 1.3 0.2 1:10.21 nova-api 10917 stack 20 0 274476 87384 3748 S 0.0 0.2 0:23.05 nova-conductor 10916 stack 20 0 274044 86908 3748 S 0.0 0.2 0:22.00 nova-conductor 10914 stack 20 0 273672 86560 3748 S 0.0 0.2 0:21.93 nova-conductor 10911 stack 20 0 273024 85892 3748 S 0.0 0.2 0:23.29 nova-conductor 10912 stack 20 0 272520 85132 3748 S 0.0 0.2 0:22.48 nova-conductor