update TiKV hardware requirements (#15282) (#15285)

Author: ti-chi-bot

best-practices/massive-regions-best-practices.md

@@ -5,7 +5,7 @@ summary: Learn how to tune the performance of TiKV with a massive amount of Regi
 
 # Best Practices for TiKV Performance Tuning with Massive Regions
 
-In TiDB, data is split into Regions, each storing data for a specific key range. These Regions are distributed among multiple TiKV instances. As data is written into a cluster, millions of or even tens of millions of Regions are created. Too many Regions on a single TiKV instance can bring a heavy burden to the cluster and affect its performance.
+In TiDB, data is split into Regions, each storing data for a specific key range. These Regions are distributed among multiple TiKV instances. As data is written into a cluster, millions of Regions might be created. Too many Regions on a single TiKV instance can bring a heavy burden to the cluster and affect its performance.
 
 This document introduces the workflow of Raftstore (a core module of TiKV), explains why a massive amount of Regions affect the performance, and offers methods for tuning TiKV performance.
 

geo-distributed-deployment-topology.md

@@ -13,7 +13,7 @@ This document takes the typical architecture of three data centers (DC) in two c
 | :-- | :-- | :-- | :-- | :-- | :-- |
 | TiDB | 5 | 16 VCore 32GB * 1 | 10.0.1.1 <br/> 10.0.1.2 <br/> 10.0.1.3 <br/> 10.0.1.4 | 10.0.1.5 | Default port <br/> Global directory configuration |
 | PD | 5 | 4 VCore 8GB * 1 | 10.0.1.6 <br/> 10.0.1.7 <br/> 10.0.1.8 <br/> 10.0.1.9 | 10.0.1.10 | Default port <br/> Global directory configuration |
-| TiKV | 5 | 16 VCore 32GB 2TB (nvme ssd) * 1 | 10.0.1.11 <br/> 10.0.1.12 <br/> 10.0.1.13 <br/> 10.0.1.14 | 10.0.1.15 | Default port <br/> Global directory configuration |
+| TiKV | 5 | 16 VCore 32GB 4TB (nvme ssd) * 1 | 10.0.1.11 <br/> 10.0.1.12 <br/> 10.0.1.13 <br/> 10.0.1.14 | 10.0.1.15 | Default port <br/> Global directory configuration |
 | Monitoring & Grafana | 1 | 4 VCore 8GB * 1 500GB (ssd) | 10.0.1.16 | | Default port <br/> Global directory configuration |
 
 ### Topology templates

hardware-and-software-requirements.md

@@ -169,16 +169,16 @@ You can deploy and run TiDB on the 64-bit generic hardware server platform in th
 >
 > - In the production environment, the TiDB and PD instances can be deployed on the same server. If you have a higher requirement for performance and reliability, try to deploy them separately.
 > - It is strongly recommended to use higher configuration in the production environment.
-> - It is recommended to keep the size of TiKV hard disk within 2 TB if you are using PCIe SSDs or within 1.5 TB if you are using regular SSDs.
+> - It is recommended to keep the size of TiKV hard disk within 4 TB if you are using PCIe SSDs or within 1.5 TB if you are using regular SSDs.
 
 Before you deploy TiFlash, note the following items:
 
 - TiFlash can be [deployed on multiple disks](/tiflash/tiflash-configuration.md#multi-disk-deployment).
-- It is recommended to use a high-performance SSD as the first disk of the TiFlash data directory to buffer the real-time replication of TiKV data. The performance of this disk should not be lower than that of TiKV, such as PCI-E SSD. The disk capacity should be no less than 10% of the total capacity; otherwise, it might become the bottleneck of this node. You can deploy ordinary SSDs for other disks, but note that a better PCI-E SSD brings better performance.
+- It is recommended to use a high-performance SSD as the first disk of the TiFlash data directory to buffer the real-time replication of TiKV data. The performance of this disk should not be lower than that of TiKV, such as PCIe SSD. The disk capacity should be no less than 10% of the total capacity; otherwise, it might become the bottleneck of this node. You can deploy ordinary SSDs for other disks, but note that a better PCIe SSD brings better performance.
 - It is recommended to deploy TiFlash on different nodes from TiKV. If you must deploy TiFlash and TiKV on the same node, increase the number of CPU cores and memory, and try to deploy TiFlash and TiKV on different disks to avoid interfering each other.
 - The total capacity of the TiFlash disks is calculated in this way: `the data volume of the entire TiKV cluster to be replicated / the number of TiKV replicas * the number of TiFlash replicas`. For example, if the overall planned capacity of TiKV is 1 TB, the number of TiKV replicas is 3, and the number of TiFlash replicas is 2, then the recommended total capacity of TiFlash is `1024 GB / 3 * 2`. You can replicate only the data of some tables. In such case, determine the TiFlash capacity according to the data volume of the tables to be replicated.
 
-Before you deploy TiCDC, note that it is recommended to deploy TiCDC on PCIe-SSD disks larger than 1 TB.
+Before you deploy TiCDC, note that it is recommended to deploy TiCDC on PCIe SSD disks larger than 500 GB.
 
 ## Network requirements