Disks in a ClickHouse® cluster

In a ClickHouse® Managed Database cluster, you can use local and network volumes. The type of disk used depends on the selected configuration line.

You can select a configuration line with the required disk type and disk size when creating a Managed Database cluster. After the cluster is created, you can change the line to another one with the same disk type and increase the disk size — scale the cluster.

Disk performance and bandwidth for different configuration lines can be viewed in the Performance and Bandwidth table.

Local disks

Configuration lines	Standard; CPU; Memory; HighFreq; Flex
Volume type	SSD NVMe volume
Technical details	The disk subsystem is configured in RAID 10 for Standard, CPU, Memory, HighFreq, and Flex lines
Advantages	Low data access latency
Usage	Suitable for tasks sensitive to read/write speed metrics
Number of volumes in DBMS	1
Changing configuration	in all configuration lines with a local disk, except Flex, you cannot increase the local disk alone; you can change the entire node configuration — scale the cluster
Detaching volume	✗
Connect to another database	✗
Create another volume, snapshot, or backup	✗
Deletion	Deleted along with all data when the cluster is deleted

Network volumes

Configuration lines	Flex
Volume type	SSD NVMe volume
Technical details	Managed by a Software-Defined Storage (SDS) system — Ceph
Advantages	triple volume replication; network volume size is independent of the number of vCPUs
Usage	Not recommended for systems sensitive to network latency and response time (latency). For example, it is suitable for archival data storage
Number of volumes in DBMS	1
Changing configuration	there is no downtime when changing the volume size; when changing the number of vCPUs and RAM, downtime depends on the number of nodes in the cluster: in single-node clusters, downtime is equal to the node reboot time (one to two minutes), and in multi-node clusters, it is equal to the time taken to switch to another node (less than one minute)
Detaching volume	✗
Connect to another database	✗
Create another volume, snapshot, or backup	✗
Deletion	Deleted along with all data when the cluster is deleted

Performance and bandwidth

Standard
CPU
Memory
HighFreq
Flex

	Volumes up to 256 GB	Volumes 512 GB	Volumes 768 GB	Volumes 1 TB	Volumes 1.5 TB	Volumes 2 TB	Volumes 2.5 TB
Bandwidth	400 MB/s	500 MB/s	600 MB/s	700 MB/s	800 MB/s	900 MB/s	1 000 MB/s
Performance (read)	25 600 IOPS	40 000 IOPS	50 000 IOPS	60 000 IOPS	70 000 IOPS	80 000 IOPS	90 000 IOPS
Performance (write)	12 800 IOPS	20 000 IOPS	25 000 IOPS	30 000 IOPS	35 000 IOPS	40 000 IOPS	45 000 IOPS

	Volumes 64 GB	Volumes 128 GB	Volumes 256 GB	Volumes 512 GB	Volumes 768 GB	Volumes 962 GB	Volumes 1.22 TB	Volumes 1.5 TB	Volumes 2 TB
Bandwidth	400 MB/s	500 MB/s	600 MB/s	700 MB/s	800 MB/s	900 MB/s	1 000 MB/s	1 100 MB/s	1 200 MB/s
Performance (read)	25 600 IOPS	40 000 IOPS	50 000 IOPS	60 000 IOPS	70 000 IOPS	80 000 IOPS	90 000 IOPS	100 000 IOPS	120 000 IOPS
Performance (write)	12 800 IOPS	20 000 IOPS	25 000 IOPS	30 000 IOPS	35 000 IOPS	40 000 IOPS	45 000 IOPS	50 000 IOPS	60 000 IOPS

	Local disk	Network volume
Bandwidth	300 MB/s	500 MB/s
Performance (read)	12 800 IOPS	25 000 IOPS
Performance (write)	6 400 IOPS	15 000 IOPS

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