What is QoS?
When it comes to QoS, we must first understand QoE
QoE is the level of joy or annoyance to the user of an application or service. It is the expectation or enjoyment of the user's experience, which varies according to the user's personality and current state. Simply put, QoE = "Quality" or "Performance" or "Comfort" as perceived by the user)
QoS
QoS is about the guarantees that the underlying network services are provided to the application layer services.
The QoS mechanism provides a means for ensuring the network resources required by the application at the time of delivery to achieve the desired level of user QoE (Quality of Experience).
As one of the basic underlying application network platforms in the future, decentralized storage must be able to provide high-quality QoS. Only developers can provide high-quality QoE based on a reliable decentralized storage platform.
Basic storage platform, what key QoS should there be
Decentralized storage platforms are also storage platforms. If you want to be commercially available, you must first achieve the QoS of basic storage platforms. So what QoS should the basic storage platform have?
1. High availability
High availability is a feature of a system to ensure a consistent level of operational performance, usually uptime, above normal.
The most important measure of high availability is the SLA, which is the Service-Level Agreement. Generally, it is expressed by the number of 9s. 99.9% is 3 9s, and 99.99% is 4 9s. This generally refers to the percentage of time that each stored content can work normally to provide services. The following table can intuitively feel the SLA.
In decentralized storage, the DownTIme calculation in the SLA means that the user's requested service is not answered within a specified time.
2. High reliability
High reliability refers to the guarantee that the sender provides the intended receiver with the correct transmission of data, as opposed to an unreliable protocol, which provides no guarantee that the data will be delivered to the intended receiver.
In decentralized storage, high reliability means that users can obtain 100% of the stored data, that is, at least one copy cannot be lost, and the specified number of copies should be in a balanced state.
3. High performance
Performance means, other relevant metrics, including
1) Transmission speed
2) Request response time
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These data are very critical and need to be counted by region and time period, because these data may be very different in different regions and different time periods.
Key QoS of Decentralized Storage
In addition to the critical QoS of the basic storage platform, decentralized storage has some additional critical QoS. The following is divided into two parts, one is the QoS of the P2P system, and the other is the QoS of the hard disk mining machine. In addition to users and miners, decentralized storage must also require other nodes (such as FileCoin's retrieval miners, even if it is other nodes, providing data) Retrieval service), this node also has QoS.
1. QoS of P2P system
The decentralized storage platform, whose transmission method adopts the data type Peer to peer transmission method (similar to BitTorrent, PPLive, EDonkey), will have the QoS of the P2P transmission system.
Key QoS of P2P transmission system:
1) The rate at which nodes with the same resource are found.
2) Quickly distinguish the time between high-speed nodes and non-high-speed nodes.
3) Useless agreement rate. In the P2P transmission system, as long as it is not the protocol consumption of actually transmitting the file content, it is a useless protocol. The useless agreement rate refers to the ratio of the size of the useless agreement to the size of all the agreements.
4) Data transmission redundancy rate. In the P2P transmission system, sometimes it will request data from PeerA, but PeerA will request data from PeerB under certain circumstances because the transmission is very slow. Both PeerA and PeerB transmit the same part of the data, which is data transmission redundancy . Data transmission redundancy rate is the proportion of redundant transmissions in normal transmissions.
5) Data request rejection rate. Sometimes when data is requested, the storage miner cannot return it because it cannot find the data. Maybe the hard disk is broken, there may be logical errors, and it does not rule out that the storage miners deliberately do evil, and there is data but not given. In any case, the data request is rejected. Then, the data request rejection rate is the ratio of rejected requests to the number of requests that normally return correct data.
6) The proportion of incorrect protocol data. Since the P2P transmission system is not so clean, there may be protocol errors due to inconsistent versions, and there may be malicious attacks by hackers to forge protocol packets, resulting in erroneous protocols. The percentage of incorrect protocol data is a measure of the percentage of P2P protocols that are incorrect.
7) NAT traversal related indicators. There are also many indicators for NAT traversal, such as penetration time, penetration rate, etc.
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2. QoS of storage miners
The health of the storage mining machine is also related to the health of the entire network. I think that in order to do a good job in decentralized storage, it is necessary to use ARM-based low-performance and low-power computers to provide storage, because such machines are low-cost, right For storage miners, the relative benefits will be more. Therefore, it is very important to extract the QoS of the storage mining machine.
1) Response speed. This is the average time to give a response after a request is received.
2) Memory cache hit rate. As a storage service, not all data can be read from the hard disk. For frequently accessed content, it will be cached in memory, and the content cache hit rate is an important indicator to measure the effectiveness of content caching and bandwidth utilization.
3) Security consumption, that is, the performance ratio of encryption and decryption. For security reasons, there will be a lot of encryption and decryption work, so how much CPU performance and memory resources these tasks occupy can be quantified.
4) Request error rate. How many requests do not return data correctly. 5) The proportion of abnormal space usage. The damaged part of the hard disk cannot be properly serviced, which is abnormal space, and the hard disk is often damaged a little, which will affect the entire area (a Plot in PPIO) and cannot provide services normally. The size of all abnormal space on the entire hard disk and the proportion of the entire space are this indicator.
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3. QoS of other nodes
1) Response speed. This is the average time it takes to give a response after a request is received.
2) Safe consumption. That is, the performance ratio generated by encryption and decryption is similar to the QoS of storage miners.
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Nodes with different roles also have their own characteristic QoS.
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