{{ $t('productDocDetail.updateTime') }}: 2025-12-18

Version below 5.8.6

• Condition 1: For 2 data copies, a pair of hard disks are required to mount on each node. Cluster node hard disks must be balanced, if node A has 2 hard disks, node B must have 2 hard disks as well.

• Condition 2: If the number of hard disks is not having the same numbers, it cannot form data disk pair.

• Condition 3: The recommended ratio of SSDs to HDDs is 1:3–7, with 1:4 recommend, that is, one SSD corresponds to four HDDs.

• Condition 4: The maximum SSD-to-HDD ratio is 1:1.

• Condition 5: The recommended SSD-to-HDD capacity ratio is 1:10 and generally should not be lower than 1:20.

HCI 5.8.6 and later version

Hybrid Datastore three Hosts and above

• Condition 1: The sum of the data disk capacity between hosts, the highest capacity, cannot exceed 80% of the sum of all the remaining hosts. Example: host A 5TB, host B 5TB, host C 5TB, host D is not allowed to exceed 12TB.

• Condition 2: The ratio of the cache disk capacity to the data disk capacity of each host should not be less than 5%. For example, host A configuration with two 480GB SSDs and ten 4TB HDDs is not allowed.

• Condition 3: The ratio of each host’s cache disks and data disks should be within 1:6. For example, host A has two cache disks and fifteen data disks, which is not allowed.

• Condition 4: It is allowed to have a data disk with different capacities in a single host, but the capacity gap of the largest data disk should not exceed two times the smallest data disk. For example, a 1TB disk and a 4TB disk can form virtual storage but do not form a 1TB disk and a 4TB disk in the same disk group. The capacity of a 4TB disk is four times larger than a 1TB disk, but the performance is the same as a 1TB disk, so a 4TB disk can easily become a performance bottleneck. The bigger the gap, the bigger the bottleneck.

1. The HDD in the host allows SAS disks and SATA disks to be mixed, but it will cause the performance of SAS disks to be equal to SATA disks (barrel effect).
2. The host is allowed to have a varying number of disks between disk groups. The main impact is that the write performance will drop slightly when the storage pool is almost full.

All-Flash Datastore three Hosts and above:

Condition 1: The sum of the data disk capacity between hosts, the highest capacity, cannot exceed 80% of the sum of all the remaining hosts. Example: host A 5TB, host B 5TB, host C 5TB, host D is not allowed to exceed 12TB.

Two hosts scenario

• Condition 1: The total capacity of the two hosts must be equal.

• Condition 2: The ratio of the cache disk capacity to the data disk capacity of each host should not be less than 5%. For example, host A configuration with two 480GB SSDs and ten 4TB HDDs is not allowed.

• Condition 3: The ratio of the number of cache disks to data disks of each host should exceed or equal to 1:6. For example, host A has two cache disks, and fifteen data disks are not allowed.

• Condition 4: It is allowed to have a data disk with different capacities in a single host, but the largest data disk capacity is not allowed to exceed 50% of the capacity of the smallest data disk. For example, a 1TB disk and a 4TB disk can form a virtual storage datastore but do not form a 1TB disk and a 4TB disk in the same disk group. The capacity of a 4TB disk is four times larger than a 1TB disk, but the performance is the same as a 1TB disk, so a 4TB disk can easily become a performance bottleneck. The bigger the gap, the bigger the bottleneck.

When expanding the capacity of two hosts in a datastore by add host, the entire HCI cluster needs to be restarted expanding by disks do not need restart.