Recommended disk configuration

Caches

Allocate a minimum of 50 GB of cache to each disk.

Cache settings cannot be modified after UIS setup finishes. If HDD expansion is required, reserve SSD space in storage planning. Make sure the size of each cache partition multiplied by the number of data disks on a storage node is smaller than the total size of SSDs deployed as caches. For example, a storage node has two 600-GB SSDs and eight HDDs, and the SSDs provide 100 GB of cache for each HDD. The total cache size is 800 GB, which is smaller than the total size of the cache disks. Typically, the actual size of a disk is smaller than the claimed size. Please use the actual size to plan storage. For illustration purposes, this document uses the claimed size. Use RAID 0 on each SSD. Do not use read-intensive SSDs as cache disks, Intel S3500 series SSDs for example.

Recommended SSD to HDD ratios are as follows:

• Use one SATA SSD to provide caches for five SATA HDDs.

• Use one SATA SSD to provide caches for four SAS HDDs.

• Use one NVMe SSD to provide caches for ten SATA HDDs.

• Use one NVMe SSD to provide caches for eight SAS HDDs.

NVMe SSDs of different models differ greatly in performance. As a best practice, use NVMe SSDs that support an IOPS of 200000 or higher.

To ensure performance, do not enable disk caching when SSDs are not enough.

Metadata disks

Metadata is used to manage the user data stored on a storage system. For high performance, save metadata on dedicated SSDs.

Storage data disks

• Deploy a minimum of four disks on each storage node. For databases, performance increases with the number of disks.

• Use RAID 0 on each SSD. You can choose to not configure RAID 0 if you use UIS 2000 G3 HCI appliance.

• Use disks at 10000 rpm (or higher).

• Use the same disk model in a cluster.

• As a best practice, use disks that have the same connector type (SAS or SATA), capacity, and rotation speed.

• The driver letters of HDD and SSD data disks can start with sd, df, nvme, fct, fio, or hio. Do not use read-intensive SSDs as data disks, Intel S3500 series SSDs for example.

• As a best practice, install the same number of data disks on servers. If you have to install different numbers of data disks, make sure the difference between the largest quantity and the smallest quantity does not exceed 20% of the largest quantity.

• For data security, use three replicas. If databases require high performance, use two replicas.

ONEStor ensures data availability through replicas. If N replicas are used, the available capacity is the raw capacity divided by N.