About recovery. Is RAID on a VPS SSD advisable for dedicated drives? Server analogue until February for free / ua-hosting.company's blog

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. Discussion of the correct logistics of restoration, methods of backup and the appropriateness of certain costs of backup in specific cases, as well as reviews and opinions from you - our dear readers and customers - about all this "disgrace". 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 hardware? What drives? Difficulties of choice. We will be glad if you join her.

Well, since the New Year is coming up, and on New Year's it is customary to give gifts, we are the hosting provider ua-hosting.company, which provides rental services for dedicated servers mainly in the Netherlands, taking this opportunity, we want to congratulate you on the upcoming New Year holidays and give you a gift present a full analogue of a dedicated server in the Netherlands FREE (conditions obtaining at the end of the article) through February: for each virtual server with a dedicated storage can be purchased up to 3, the IPv4 addresses and increase traffic at the rate of $ 15 + for each a surcharge nye 10TB.








But back to the topic. Recently, we have faced serious criticism of our decisions, which comes primarily from competitors, not customers. The current market situation forces all hosting providers to provide better services at lower prices. The main argument in criticizing our company is the lack of RAID on a virtual server with a dedicated SSD drive:

The problem is not that the drive is dying or not. And the fact that the virtual server service is being offered, which, in my opinion, by default implies a fail-safe disk subsystem from the provider. But in the case of hosting_manager, this is not so.
And to offer such a service with premium quality sauce is at least misleading users.

Let's see if this is true. Is RAID really important in this particular case? Perhaps, how paradoxical this may sound, this solution is more reliable and cost-effective without RAID, and an additionally thought-out backup or a well-developed disaster recovery plan to eliminate the alleged shortcomings of the service offered to the public?

About recovery and backup in general.

Golden Rule:

There are administrators who do not backup and those who already do.

RAID RAID arrays are created to increase storage performance, as well as to increase fault tolerance. This is undeniable. After all, all drives sooner or later may fail, and the drive array will always work faster than a single drive. But is it always advisable?

The golden rule tells us only about the need to create backups - backups, but does not mean at all that RAID is required 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 collapse at any time;
- in the event of a drive failure, when recovery takes too much time due to the large amount of data, the inability to quickly transfer the required amount and the need to configure the server software again, which will take longer than is permissible for this particular case;
- in the case of renting dedicated servers and a lack of understanding about building the right plan and recovery scheme, when RAID is a cost-effective solution - cost-effective.

In other words, a RAID array can help in certain cases 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.

Is he needed on 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 you provide an additional drive for building RAID1 for a specific virtual machine, the price will increase by 2 times, while the reliability will become only a fraction of a percent higher due to the use of RAID, and the read performance will increase just not needed for most subscribers. At the same time, for less than 2 times a lot of money, you can provide a much higher% of reliability and fault tolerance by applying disaster recovery or backup logistics, depending on the needs of a particular project.

Here we consider the factors why we decided to provide these virtual servers without RAID, in addition to the inefficient growth of the cost of the service in this case. Is the solution really unreliable without RAID?

Why the accidental failure of SSD drives is extremely rare and you should not worry about it when renting a virtual server service with a dedicated SSD drive.

SSD, unlike HDD-drives, has no moving parts, so the mechanical processes associated with read and write operations are completely absent. This means that the probability of accidental SSD failure due to the influence of mechanical factors, which 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 ones. That is, more than 3% of 4 falls under a fairly real forecast precisely thanks to the physics of SSD. Unlike HDDs, SSDs are killed by rewriting cycles and the number of these cycles is well known for a particular type of solid state drive. Therefore, the state of the drives can be monitored and more or less accurately predict the need for their replacement. That is, statistics show that the% of random failures lies at approximately the level of% data loss for all other reasons, including a global problem on the server as a whole, which leads to data loss.

This is also proved by our experiment. We started to providesimilar solutions, only on less reliable platforms more than 5 years ago and on less capacious SSD drives of 120GB each, since June 2015. And so far, on hundreds of virtual servers, we have not fixed the problem of failure of the SSD-drive, both for random and natural reasons.

The logical question is that if reliability is so high, why overpay?

Moreover, RAID is not a backup, and in the case of SSD-drives it is very common opinion that since SSD-drives are utilized evenly by rewriting cycles, they will die in a RAID1 array almost at the same time, or even faster, since RAID creates additional load and in some cases can 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 recycling. But this is a topic for a separate article and study.

Moreover, you need to remember such a fact that renting a virtual server with a dedicated drive - only you will use its resource, which means that utilization, which is predicted for natural reasons, can go very slowly. Since most web projects hosted on such VPS do not create the number of write operations sufficient to recycle the drive faster than in 2 years.

Backup and recovery.

Nevertheless, you must not forget about the backup and think over a disaster recovery plan, in case your VPS falls into that unfortunate% within 2 years, the probability of which, although extremely small, is present.

We offer our customers the following solutions:

- mandatory backup 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 bring down prices even more), save traffic and save extra load, providing an up-to-date copy with many copies of files that have undergone changes and will allow you to restore a virtual server in a period of 1 hour, depending on the characteristics of a particular server;
- rental of an identical additional VPS, which will work in a mini-cluster and always contain identical information, and, possibly, balance the load, which will provide fault tolerance and, probably, will provide the ability to withstand 2 times large peak loads.

The first option is acceptable for most webmasters, since a simple one hour or even a few hours (worst case scenario) for 2 years will cost much less than VPS SSDs with two dedicated drives in RAID1, which do not cancel the need to purchase backup services since RAID1 is not a backup.

The second option is for projects for which even an hour of downtime is critical. At the same time, it is also much better than the RAID1 option, as it will allow it to withstand heavy loads and balance the load between virtual machines, subsequently building a fairly fault-tolerant cluster distributed across nodes in different data center modules. In fact, it also provides the ability to scale. But of course, he will require escort costs.

It is for this reason that we have not yet introduced nodes with RAID1 VPS on dedicated SSDs, unlike HDDs (there you have a choice whether to risk data or not, and the risk is high, but, as we see, for many clients it is acceptable there , price is more important, and data is not always important). We will definitely publish the statistics of HDD and SSD failures 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 the RAID1 SSD VPS solution for you on dedicated drives, in any case, please take part in the survey below to understand how many real people have such needs.

PS We will be grateful for your feedback. We want to thank you for your attention and talk about the conditions for providing 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 02/01/2017 without payment , in the case of an order at any time until the end of January (the sooner checkout, the more free use you will receive). Indicate 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 cancellation of the service, must be completed before February 20), and rent until February will be absolutely free. We also guarantee a refund for any reason within a month for all participants of the action if you do not like the service.We will be grateful for feedback and comparisons, similar to this:

Test results on a real project .

But criticism is also acceptable, we work for you and want to be better, you need to - criticize, we will translate your wishes into reality, ua-hosting.company - happy to make you happier!