Hi Patrik,
The RAM requirement for HSX nodes is generally based on the actual drive size rather than the usable drive size. Therefore, if the documentation specifies a requirement of 768GB RAM for 18TB drives, this would typically apply to the actual size of the drives, not the formatted usable size.
As per the Commvault Validated Reference Design Specification for Commvault Cloud HyperScale X Software on Dell R760XD2 with 24 20TB Hard Drives, there is an increased memory requirement. According to the technical specifications for HyperScale X Appliance models, for servers with 20TB drives, 768GB RAM is required. This specification is based on the actual drive size, not the formatted usable size. Therefore, it is recommended to equip the servers with 768GB RAM to ensure optimal performance and stability.
Dell R660XS : https://cloud.kapostcontent.net/pub/cdbb3a74-edbb-4e41-acc7-8c7741e54aef/commvault-hyperscale-x-validated-reference-design-for-dell-r660xs?kui=t0E4XwM8BNRbUADJ_bsR7A
Dell R760 : https://cloud.kapostcontent.net/pub/6d4baf09-eb8d-4448-a61a-7aa02b308b6e/commvault-hyperscale-x-validated-reference-design-for-dell-r760?kui=EQLW9j14AQE2Oz7l3Eb50w
Dell R760XD2 : https://cloud.kapostcontent.net/pub/34c49a0b-13e4-48be-88ef-b376d53b7baf/commvault-hyperscale-x-validated-reference-design-for-dell-r760xd2?kui=ZsPNL7tbcaV2lycNpioVFg
Hope this helps!
In this case we got an approval from Commvault Development that it is ok to use 512k RAM as the drives will be formatted to 18TB.
If you get into this situation I would recommend to get confirmation from dev before proceeding with installation, or, of course, order a correct ref.arch server from scratch to avoid uncertainty.
/P