Preparing to run the benchmark

If the cluster nodes have SSD/NVMe caches, make sure they have been flushed before running any benchmarks. You can check the caches as follows:

On a cluster node, run:
```
# vstorage -c <cluster_name> top
```
While in the text-based dashboard, press c to expand the chunks tab, and then cycle columns by pressing i until you see the JRN_FULL and FLAGS columns.
Wait until JRN_FULL is 0% and each CS ID is marked by the c flag, for example, JCc. This may take some time when the cluster is not under I/O load. The journal cleaning can be forced by running:
```
# vstorage -c <cluster_name> set-config cs.force_checkpoint=1
# vstorage -c <cluster_name> set-config cs.force_checkpoint=0
```