About recovery. Is RAID on a VPS SSD advisable in case of dedicated drives? Analog server until February for free
This post is the result of numerous criticisms of our new line - a full-fledged analogue of dedicated servers in the Netherlands , received from competitors. A discussion of the correct restoration logistics, backup methods and the feasibility of certain backup costs in specific cases, as well as feedback and opinion from you - our dear readers and customers - about all this “ugliness”. We also want to draw your attention to the fact that in parallel, at Geektimes, we are starting a discussion on another important topic: VPS in the “cloud” or in the “hardware”? What drives? Difficulties of choice. We will be glad if you join her.
Well, since the New Year is coming soon, and it is customary to give presents for the New Year, we are the hosting provider ua-hosting.company, which provides rental services for dedicated servers mainly in the Netherlands, taking this opportunity to wish you a happy New Year holidays and donate A gift is a full-fledged analog of a dedicated server in the Netherlands for FREE (conditions for receiving at the end of the article) until February:
')
For each virtual server with a dedicated drive, you can buy up to 3 IPv4 addresses and increase traffic at the rate of + $ 15 for each additional 10TB.
But back to the topic. Recently, we have come across serious criticism of our decisions, which comes primarily from competitors, not customers. The current conjuncture of the market forces all hosting providers to provide better services at lower prices. The main argument in the criticism of our company is the lack of RAID on a virtual server with a dedicated SSD-drive:
Let's see if this is true. Is RAID important in this particular case? Perhaps, paradoxically, it doesn’t sound, this solution is more reliable and cost-effective without RAID, and a sufficiently well-thought-out backup or well-developed disaster recovery plan is needed to eliminate the perceived flaws of the service offered to the public?
Golden Rule:
Raid RAID arrays are created in order to increase storage performance, as well as to increase fault tolerance. It is indisputable. After all, all drives can fail sooner or later, and an array of drives will always run faster than a single drive. But is it always advisable?
The golden rule tells us only about the need for backup copies - backups, but does not mean that RAID is mandatory and is always the best solution.
RAID is desirable in such cases:
- the performance of one drive is not enough to meet the needs of the project;
- HDD-type drive and failure is difficult to predict, there is a high probability of crash at any moment;
- in the event of a drive failure, when recovery takes too much time due to the large amount of data, the impossibility of quickly transferring the required volume and the need to configure the server software again, which will take longer than is acceptable for this particular case;
- in case of rental of dedicated servers and lack of understanding about building the right plan and recovery scheme, when RAID is the best-priced solution - cost-effective.
In other words, a RAID-array can help in certain cases to increase fault tolerance, but it is not a backup at all, and in case of global problems with the platform, or hacking, it does not protect against data loss.
Does he need these services?
VPS (KVM) - E5-2650 v4 (6 Cores) / 10GB DDR4 / 240GB SSD / 1Gbps 10TB - $ 29 per month
VPS (KVM) - E5-2650 v4 (12 Cores) / 20GB DDR4 / 480GB SSD / 1Gbps 20TB - for $ 49 per month
No, and the main reason is that if an additional drive is provided for building RAID1 for a particular virtual machine, the price will increase by 2 times, while the reliability will be only a fraction of% higher due to the use of RAID, and the reading performance increase is simply not needed for the most part of subscribers. At the same time, in less than 2 times more money, you can provide a much larger% of reliability and fault tolerance by applying disaster recovery or redundancy logistics, depending on the needs of a specific project.
Here we consider the factors why we decided to still provide these virtual servers without RAID, in addition to the inefficient increase in the cost of services in this case. Is the solution really unreliable without RAID?
SSD, in contrast to HDD drives, has no moving parts, thus the mechanical processes associated with read and write operations are completely absent. This means that the probability of accidental failure of the SSD due to the influence of mechanical factors that make the main contribution to the% probability of failure for random reasons is negligible.
So, according to statistics, less than 1% of SSD drives fail in the first 2 years for random reasons. And less than 4% - for all other reasons, including random. That is, more than 3% of the 4 falls under a rather real forecast precisely because of SSD physics. Unlike HDD, SSDs are killed by rewriting cycles and the number of these cycles is well known for a particular type of solid-state drive. Therefore, it is possible to monitor the state of the drives and more or less accurately predict the need for their replacement. That is, statistics show that% of random failures lies at about the% data loss level for all other reasons, including the global problem on the server as a whole, which leads to data loss.
This is also proved by our experiment. We started to provide similar solutions, only on less reliable platforms more than 5 years old and on less capacious SSD-drives with 120GB each, from June 2015. And still on hundreds of virtual servers, we have not fixed the problem of failure of the SSD-drive, both for random and for a natural reason.
A logical question arises, that if reliability is so high, why overpay?
Moreover, RAID is not a backup copy, and in the case of SSD drives, it is a very common opinion that since SSD drives are utilized evenly by rewriting cycles, they will die in the RAID1 array almost at the same time, or even faster, as RAID creates additional load and in some cases may even reduce the lifespan of a drive. The use of drives in RAID1 arrays from different manufacturers is not always a good solution, as well as drives with different degrees of utilization. But this is a topic for a separate article and research.
Moreover, it is necessary to remember the fact that when renting a virtual server with a dedicated drive, you will use its resource only, which means that the utilization predicted by natural reasons can go very slowly. Since most of the web projects that are hosted on such VPS, do not create the number of write operations, sufficient to dispose of the drive in less than 2 years.
Nevertheless, you should not forget about the backup and consider an emergency recovery plan, in case your VPS gets into that unhappy% within 2 years, the probability of which, although extremely small, is present.
We offer our clients the following solutions:
- Mandatory backups to an external server using the rsync / rsnapshot method, which will cost $ 6 or $ 12 / month for an additional 256 or 512 GB (in the near future we will drop prices even more), save traffic and relieve unnecessary load by providing an up-to-date copy with many copies of files that have undergone changes and will allow to restore the virtual server in a period of 1 hour, depending on the particular server;
- rental of an identical additional VPS, which will work in a mini-cluster and always contain identical information, and, perhaps, balance the load, which will provide fault tolerance and, probably, will provide the ability to withstand twice the large peak loads.
The first option is acceptable for most webmasters, since idle time per hour or even several hours (the worst scenario) for 2 years will be much cheaper than VPS SSD with two dedicated drives in RAID1, which do not cancel the need to buy backup services, since RAID1 is not a backup.
The second option is for projects for which even an idle hour is critical. At the same time, it is also much better than the RAID1 option, since it will allow it to withstand heavy loads and balance the load between virtual machines, having built in future a rather fault-tolerant cluster distributed over the nodes in different data center modules. In fact, it also provides the possibility of scaling. But of course, he will require maintenance costs.
It is for this reason that we have not yet introduced nodes with RAID1 VPS on dedicated SSD drives, unlike HDDs (you have a choice whether to risk data or not, and the risk is high, but, as we see, for many customers it is acceptable , price is a more important factor, and data is not always important). Statistics of HDD and SSD failures will be published in the course of further work of this service.
Nevertheless, we are ready to put the question to the vote and if you have such a need - we are ready to provide a RAID1 SSD VPS solution for you on dedicated drives, in any case, please take part in the survey below in order to understand how many real people have such needs.
PS We appreciate your feedback. We would like to thank you for your attention and tell us about the condition of the bonus . Everything, as in previous times, for any of the virtual servers in the Netherlands on dedicated drives:
ua-hosting.company / vds - only in the Netherlands, you can order here;
VPS (KVM) - E5-2650 v4 (6 Cores) / 10GB DDR4 / 240GB SSD / 1Gbps 10TB - $ 29 per month;
VPS (KVM) - E5-2650 v4 (12 Cores) / 20GB DDR4 / 480GB SSD / 1Gbps 20TB - for $ 49 per month;
VPS (KVM) - E5-2650 v4 (6 Cores) / 10GB DDR4 / 4TB SATA / 1Gbps 10TB - $ 29 per month;
VPS (KVM) - E5-2650 v4 (12 Cores) / 20GB DDR4 / 2 x 4TB RAID1 SATA / 1Gbps 20TB - for $ 49 per month.
We are ready to provide use until 01.02.2017 without payment , in the case of an order at any time until the end of January (the earlier you issue, the more free use you will receive). Enter the order number in the comments to this post and you will receive a bonus - the payment already made will be taken into account as payment for February (extension for March or refusal of the service, you need to make it until February 20th), and rent until February will be absolutely free. We also guarantee a refund for any reason within a month for all participants of the promotion, if you do not like the service. We would be grateful for the reviews and comparisons, like this:
Test results on a real project .
But criticism is also permissible, we work for you and want to be better, you need to - criticize, we will translate your wishes into reality, ua-hosting.company - glad to make you happier!
Well, since the New Year is coming soon, and it is customary to give presents for the New Year, we are the hosting provider ua-hosting.company, which provides rental services for dedicated servers mainly in the Netherlands, taking this opportunity to wish you a happy New Year holidays and donate A gift is a full-fledged analog of a dedicated server in the Netherlands for FREE (conditions for receiving at the end of the article) until February:
')
For each virtual server with a dedicated drive, you can buy up to 3 IPv4 addresses and increase traffic at the rate of + $ 15 for each additional 10TB.
But back to the topic. Recently, we have come across serious criticism of our decisions, which comes primarily from competitors, not customers. The current conjuncture of the market forces all hosting providers to provide better services at lower prices. The main argument in the criticism of our company is the lack of RAID on a virtual server with a dedicated SSD-drive:
The problem is not that the drive dies or not. And the fact that the proposed virtual server service, which, in my opinion, by default implies a fault-tolerant disk subsystem by the provider. But in the case of hosting_manager, this is not the case.
And to offer such a service with a premium quality sauce is at least misleading users.
Let's see if this is true. Is RAID important in this particular case? Perhaps, paradoxically, it doesn’t sound, this solution is more reliable and cost-effective without RAID, and a sufficiently well-thought-out backup or well-developed disaster recovery plan is needed to eliminate the perceived flaws of the service offered to the public?
On the restoration and backup in general.
Golden Rule:
There are admins who do not make backups and those that already do.
Raid RAID arrays are created in order to increase storage performance, as well as to increase fault tolerance. It is indisputable. After all, all drives can fail sooner or later, and an array of drives will always run faster than a single drive. But is it always advisable?
The golden rule tells us only about the need for backup copies - backups, but does not mean that RAID is mandatory and is always the best solution.
RAID is desirable in such cases:
- the performance of one drive is not enough to meet the needs of the project;
- HDD-type drive and failure is difficult to predict, there is a high probability of crash at any moment;
- in the event of a drive failure, when recovery takes too much time due to the large amount of data, the impossibility of quickly transferring the required volume and the need to configure the server software again, which will take longer than is acceptable for this particular case;
- in case of rental of dedicated servers and lack of understanding about building the right plan and recovery scheme, when RAID is the best-priced solution - cost-effective.
In other words, a RAID-array can help in certain cases to increase fault tolerance, but it is not a backup at all, and in case of global problems with the platform, or hacking, it does not protect against data loss.
Does he need these services?
VPS (KVM) - E5-2650 v4 (6 Cores) / 10GB DDR4 / 240GB SSD / 1Gbps 10TB - $ 29 per month
VPS (KVM) - E5-2650 v4 (12 Cores) / 20GB DDR4 / 480GB SSD / 1Gbps 20TB - for $ 49 per month
No, and the main reason is that if an additional drive is provided for building RAID1 for a particular virtual machine, the price will increase by 2 times, while the reliability will be only a fraction of% higher due to the use of RAID, and the reading performance increase is simply not needed for the most part of subscribers. At the same time, in less than 2 times more money, you can provide a much larger% of reliability and fault tolerance by applying disaster recovery or redundancy logistics, depending on the needs of a specific project.
Here we consider the factors why we decided to still provide these virtual servers without RAID, in addition to the inefficient increase in the cost of services in this case. Is the solution really unreliable without RAID?
Why accidental SSD drive failure is extremely rare and you shouldn’t worry about it when renting a virtual server service with a dedicated SSD drive.
SSD, in contrast to HDD drives, has no moving parts, thus the mechanical processes associated with read and write operations are completely absent. This means that the probability of accidental failure of the SSD due to the influence of mechanical factors that make the main contribution to the% probability of failure for random reasons is negligible.
So, according to statistics, less than 1% of SSD drives fail in the first 2 years for random reasons. And less than 4% - for all other reasons, including random. That is, more than 3% of the 4 falls under a rather real forecast precisely because of SSD physics. Unlike HDD, SSDs are killed by rewriting cycles and the number of these cycles is well known for a particular type of solid-state drive. Therefore, it is possible to monitor the state of the drives and more or less accurately predict the need for their replacement. That is, statistics show that% of random failures lies at about the% data loss level for all other reasons, including the global problem on the server as a whole, which leads to data loss.
This is also proved by our experiment. We started to provide similar solutions, only on less reliable platforms more than 5 years old and on less capacious SSD-drives with 120GB each, from June 2015. And still on hundreds of virtual servers, we have not fixed the problem of failure of the SSD-drive, both for random and for a natural reason.
A logical question arises, that if reliability is so high, why overpay?
Moreover, RAID is not a backup copy, and in the case of SSD drives, it is a very common opinion that since SSD drives are utilized evenly by rewriting cycles, they will die in the RAID1 array almost at the same time, or even faster, as RAID creates additional load and in some cases may even reduce the lifespan of a drive. The use of drives in RAID1 arrays from different manufacturers is not always a good solution, as well as drives with different degrees of utilization. But this is a topic for a separate article and research.
Moreover, it is necessary to remember the fact that when renting a virtual server with a dedicated drive, you will use its resource only, which means that the utilization predicted by natural reasons can go very slowly. Since most of the web projects that are hosted on such VPS, do not create the number of write operations, sufficient to dispose of the drive in less than 2 years.
Backup and restore.
Nevertheless, you should not forget about the backup and consider an emergency recovery plan, in case your VPS gets into that unhappy% within 2 years, the probability of which, although extremely small, is present.
We offer our clients the following solutions:
- Mandatory backups to an external server using the rsync / rsnapshot method, which will cost $ 6 or $ 12 / month for an additional 256 or 512 GB (in the near future we will drop prices even more), save traffic and relieve unnecessary load by providing an up-to-date copy with many copies of files that have undergone changes and will allow to restore the virtual server in a period of 1 hour, depending on the particular server;
- rental of an identical additional VPS, which will work in a mini-cluster and always contain identical information, and, perhaps, balance the load, which will provide fault tolerance and, probably, will provide the ability to withstand twice the large peak loads.
The first option is acceptable for most webmasters, since idle time per hour or even several hours (the worst scenario) for 2 years will be much cheaper than VPS SSD with two dedicated drives in RAID1, which do not cancel the need to buy backup services, since RAID1 is not a backup.
The second option is for projects for which even an idle hour is critical. At the same time, it is also much better than the RAID1 option, since it will allow it to withstand heavy loads and balance the load between virtual machines, having built in future a rather fault-tolerant cluster distributed over the nodes in different data center modules. In fact, it also provides the possibility of scaling. But of course, he will require maintenance costs.
It is for this reason that we have not yet introduced nodes with RAID1 VPS on dedicated SSD drives, unlike HDDs (you have a choice whether to risk data or not, and the risk is high, but, as we see, for many customers it is acceptable , price is a more important factor, and data is not always important). Statistics of HDD and SSD failures will be published in the course of further work of this service.
Nevertheless, we are ready to put the question to the vote and if you have such a need - we are ready to provide a RAID1 SSD VPS solution for you on dedicated drives, in any case, please take part in the survey below in order to understand how many real people have such needs.
PS We appreciate your feedback. We would like to thank you for your attention and tell us about the condition of the bonus . Everything, as in previous times, for any of the virtual servers in the Netherlands on dedicated drives:
ua-hosting.company / vds - only in the Netherlands, you can order here;
VPS (KVM) - E5-2650 v4 (6 Cores) / 10GB DDR4 / 240GB SSD / 1Gbps 10TB - $ 29 per month;
VPS (KVM) - E5-2650 v4 (12 Cores) / 20GB DDR4 / 480GB SSD / 1Gbps 20TB - for $ 49 per month;
VPS (KVM) - E5-2650 v4 (6 Cores) / 10GB DDR4 / 4TB SATA / 1Gbps 10TB - $ 29 per month;
VPS (KVM) - E5-2650 v4 (12 Cores) / 20GB DDR4 / 2 x 4TB RAID1 SATA / 1Gbps 20TB - for $ 49 per month.
We are ready to provide use until 01.02.2017 without payment , in the case of an order at any time until the end of January (the earlier you issue, the more free use you will receive). Enter the order number in the comments to this post and you will receive a bonus - the payment already made will be taken into account as payment for February (extension for March or refusal of the service, you need to make it until February 20th), and rent until February will be absolutely free. We also guarantee a refund for any reason within a month for all participants of the promotion, if you do not like the service. We would be grateful for the reviews and comparisons, like this:
Test results on a real project .
But criticism is also permissible, we work for you and want to be better, you need to - criticize, we will translate your wishes into reality, ua-hosting.company - glad to make you happier!
Source: https://habr.com/ru/post/318774/
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