Files under kvstore directory

[pkeller]

We've recently seen a significant spike in memory utilization on our search heads ... Looking at the files opened by mongod I'm seeing info like this:

-rw------- 1 root root 16777216 Dec 7 16:37 s_SA-AccyUyi@longstring@.0
-rw------- 1 root root 33554432 Sep 15 20:58 s_SA-AccyUyi@longstring@.1
-rw------- 1 root root 536608768 Nov 16 02:36 s_SA-AccyUyi@longstring@.10
-rw------- 1 root root 536608768 Sep 19 23:28 s_SA-AccyUyi@longstring@.11
-rw------- 1 root root 536608768 Dec 7 16:38 s_SA-AccyUyi@longstring@.12
-rw------- 1 root root 67108864 Sep 15 20:58 s_SA-AccyUyi@longstring@.2
-rw------- 1 root root 134217728 Dec 7 16:29 s_SA-AccyUyi@longstring@.3
-rw------- 1 root root 268435456 Dec 7 16:38 s_SA-AccyUyi@longstring@.4
-rw------- 1 root root 536608768 Sep 19 23:28 s_SA-AccyUyi@longstring@.5
-rw------- 1 root root 536608768 Dec 7 16:38 s_SA-AccyUyi@longstring@.6
-rw------- 1 root root 536608768 Dec 7 16:38 s_SA-AccyUyi@longstring@.7
-rw------- 1 root root 536608768 Sep 19 23:32 s_SA-AccyUyi@longstring@.8
-rw------- 1 root root 536608768 Sep 19 23:31 s_SA-AccyUyi@longstring@.9 

Any idea why there are so many versions of some of these? ... shouldn't there typically only be a ".0" and a ".ns" file for each collection?

Thank you