T186562 requires that 9 machines in the RESTBase Cassandra cluster be re-imaged in order to configure the SmartArray controller in HBA mode. We would like to use the first of these as an opportunity to conduct an experiment whereby the 5 1T Samsung SSD 850 devices would be replaced with 4 of either the 1.6T Intel, or HP SSDs used elsewhere in the cluster.
More detailed rationale for this can be found in T189057: Understand (and if possible, improve) cluster performance under the new storage strategy, but short-version: We have a broad matrix of host-disk combinations, each with differing IO performance, but the combination of HP and Samsung disks seems problematic. We have been treating this as an issue of relatively poor performance of these HPs when compared to Dells, but restbase2009, the one HP that does not have Samsungs would seem to call this into question, (it is populated with HP LK1600GEYMV devices).