Store vmstat data to see when the host is running low on memory

vmstat 5 10
<verbatim>
procs -----------memory---------- ---swap-- -----io---- -system-- -----cpu------
 r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa st
 2  0 107184 13671396 1967828 73863552    0    1     0    33    0    0 18  1 80  1  0
 2  1 107184 13671476 1967828 73863552    0    0     0    22 4346 5371 11  1 88  1  0
 1  0 107184 13669244 1967828 73863552    0    0     0    45 4991 5907 13  1 86  1  0
 2  0 107184 13670680 1967828 73863552    0    0     0   198 4341 5371 11  1 87  1  0
 1  0 107184 13669668 1967828 73863552    0    0     0    32 4910 5509 11  1 87  1  0
 1  0 107184 13670744 1967828 73863552    0    0     0    68 4513 6001 11  1 87  1  0
 4  0 107184 13669328 1967828 73863552    0    0     0    33 5002 5906 11  1 87  1  0
 2  0 107184 13670512 1967828 73863552    0    0     0    40 4495 5793 11  1 87  1  0
 2  0 107184 13671172 1967828 73863552    0    0     0    53 4665 5230 11  1 87  2  0
 2  1 107184 13671704 1967828 73863552    0    0     0    15 4337 4935 11  1 88  1  0
</verbatim>
The "so" column should be zero most of the time.