General requirements

Verify that all servers to be joined to the cluster meet the following general requirements.

Storage requirements

The following table lists the minimum and recommended storage requirements according to the disk roles (refer to About the storage cluster):

Disk role	Quantity	Disk size	Type	Endurance
System	One disk per node	100 GB minimum 250 GB recommended	SATA/SAS HDD minimum SATA/SAS SSD recommended	—
Metadata	One disk per node Five disks recommended for one cluster	100 GB	Enterprise-grade SSD with power loss protection	1 DWPD minimum
Cache	Optional One SSD disk per 4-12 HDDs	100+ GB	Enterprise-grade SSD with power loss protection and 75 MB/s sequential write performance per serviced HDD	1 DWPD minimum 10 DWPD recommended
Storage	At least one per cluster	100 GB minimum Unlimited size on a physical server; 10 TB maximum recommended inside a virtual machine	SATA/SAS HDD or enterprise-grade SATA/SAS/NVMe SSD with power loss protection	1 DWPD minimum

CPU and RAM reservations

The following table lists the amount of RAM and CPU cores that will be reserved on one node, according to the services you will use:

Service		Management node		Secondary node
		RAM1 Use only Error correction code (ECC) memory, to avoid data corruption.	CPU cores2 A CPU core here is a physical core in a multicore processor (hyperthreading is not taken into account).	RAM3 Use only Error correction code (ECC) memory, to avoid data corruption.	CPU cores4 A CPU core here is a physical core in a multicore processor (hyperthreading is not taken into account).
System		4.5 GB	1 core	1.5 GB	1 core
Storage services: each disk with Metadata, Storage, or Cache role (any size)5 For clusters larger than 1 PB of physical space, add 0.5 GB of RAM per Metadata service.		0.5 GB	0.2 cores	0.5 GB	0.2 cores
Compute6 The recommended configuration for a compute cluster node starts with 64+ GB and 16+ cores.	Service	8 GB	1 core
	Each virtual machine	128 MB		128 MB
	Database cache	up to 10% of node RAM
	Load balancer (add-on service)	1.5 GB	0.5 cores
	Kubernetes (add-on service)	1 GB	0.5 cores
	Metering (add-on service)	3 GB	1 core
Backup Gateway7 When working with public clouds and NFS, Backup Gateway consumes as much RAM and CPU as with a local storage.		1 GB	0.5 cores	1 GB	0.5 cores
S38 By default, each S3 node runs 4 S3 gateways and can run up to 10 NS and 10 OS instances, but the entire S3 cluster cannot host more than 24 OS and 16 NS instances. The number of OS and NS services is defined during the initial S3 cluster setup. Adding more nodes to the S3 cluster does not affect it. The CPU and RAM reservations depend on the number of S3 nodes. Generally, the larger the S3 cluster, the less resources are reserved on each node.	Each S3 gateway	256 MB	1 core	256 MB	1 core
	Each OS service	256 MB	0.1 cores	256 MB	0.1 cores
	Each NS service	512 MB	0.2 cores	512 MB	0.2 cores
NFS	Service	4 GB	1 core	4 GB	1 core
	Each share9 The RAM reservation for an NFS share depends on the number of cluster nodes. The larger the NFS cluster, the less RAM is reserved on each node.	up to 9 GB	up to 8 cores	up to 9 GB	up to 8 cores
iSCSI		1 GB	1 core	1 GB	1 core

These reserved values correspond to absolute minimum requirements. In general, the more resources you provide for your cluster, the better it works. All extra RAM is used to cache disk reads, while extra CPU cores increase the performance and reduce latency.

CPU and RAM limits

The following table lists the current RAM and CPU limits for Virtuozzo Hybrid Infrastructure servers:

Hardware	Theoretical	Certified
RAM	64 TB	1 TB
CPU	5120 logical CPUs10 A logical CPU is a core (thread) in a multicore (multithreading) processor.	384 logical CPUs11 A logical CPU is a core (thread) in a multicore (multithreading) processor.

CPU recommendations

• The minimum CPU frequency for Virtuozzo Hybrid Infrastructure servers is 2.0 GHz. The recommended CPU frequency is at least 2.4 GHz.
• CPU frequency affects the cluster performance. Higher CPU frequency reduces latency almost linearly, thus increasing the performance. If other CPU parameters are the same, higher CPU frequency is preferable to a larger number of CPU cores.
• Nodes running the metadata service should have high CPU frequency, because this service is CPU intensive.
• To improve erasure coding performance, it is recommended to use CPUs that support the AVX-512 instruction set, such as Intel Xeon Silver 4110, Intel Xeon Gold 5115, Intel Xeon Platinum 8171, or newer.

Network interface requirements

At least 2 x 10 GbE interfaces are recommended, for internal and external traffic; 25 GbE, 40 GbE, and 100 GbE are even better. Bonding is recommended. However, for external traffic, you can start with 1 GbE links, but they can limit cluster throughput on modern loads.