SATA, SAS or SSD disks: which is better for a server?

[OyaYansa]

A server is, in essence, a computer like any other, so it is important to pay attention to the tasks you will perform to choose the right components to mount your server, ensuring that the budget does not fire more than expected.

Within the different types of components specifically designed for servers, it is possible to emphasize the section of storage.

The storage system is one of the basic pillars for a server, since one of the main functions of any server will be to store the data that it receives from other computers or that users keep in it. Depending on the type of data that is stored and the needs of the traffic that will support that server, it is advisable to choose one type of disk or another.

Obviously you will not need the same capacity and speed of access to the data a home server in which you save the familiar files or your private mail server, that the necessary performance in the server of a company with 500 users connecting simultaneously.

What do the acronyms SATA, SAS or SSD mean?
Acronyms, damn acronyms that hide the true meaning of things and make everything seem more complicated than it really is. We will unmask what the acronyms SATA, SAS and SSD mean!

SSD (Solid State Drive)

As you will know by now, SSD is a data storage technology that relies on non-volatile memory chips similar to those in RAM or USB flash drives, where data is stored by electrical impulses, rather than on a magnetic disk as in traditional hard disks or HDD (Hard Disk Drive).

With no moving parts or writing heads, the SSD's responsiveness is immediate. For this reason, SSDs offer far superior performance than traditional hard drives.

On the other hand, we find the acronym SATA and SAS, which unlike SSD is not a storage medium like SSD, but a connection interface that allows different data transfer rates at different transfer speeds.

Therefore, it is important to differentiate between the storage system (SSD or HDD) and the connection interface for those storage systems (SAS or SATA)

Serial Advanced Technology Attachment (SATA)

It is one of the most po[CENSORED]r connection interfaces for storage being the most used in home storage systems and is the most common on the motherboards of personal computers and laptops as it offers a very balanced performance for this type of platforms .

The SATA interface replaced the already obsolete Parallel ATA or IDE (Integrated Drive Electronics), surpassing its transfer rates, which went from little more than 133 MB / s to the 150 MB / s of the first version of SATA. Currently the third version (SATA 3) is used, with up to 600 MB / s.

However, as we will see later, perhaps the SATA interface is not the most suitable for a high-performance server.

The SAS (Serial Attached SCSI)

This interface is probably the most unknown to the public since its use has been extended almost exclusively in the field of enterprise storage and massive servers, despite having a very similar development and close to SATA.

As in the case of SATA, the SAS interface replaced the SCSI (Small Computer System Interface) standard present in most servers of the time, but insufficient for the enormous flow that required the proliferation of networked services and the increase of devices connected to the servers.

The arrival of the SAS interface allowed higher rates of data transfer and connect more devices simultaneously.

The SAS interface is also in its third version and has gone from a bandwidth of 3 Gbit / s of the first version (SAS-1) to the 12 Gbit / s of the current version (SAS-3) or the 22 , 5 Gbit / s expected for its next release (SAS-4).

Differences between SATA and SAS
It should be remembered that both SATA and SAS are connection interfaces that are integrated into a storage system (usually HDD). However, simply incorporating one of the two interfaces already conditions the characteristics and performance of that storage unit.

If the SAS interface has a higher bandwidth to carry a greater number of data at the same time, it would be a waste not to use it with storage systems capable of running at a faster rate. Said and done!

One of the main differences between hard disks using a SAS and SATA interface is that, while in the case of SATA, they usually spin at a speed between 5,400 and 7,200 rpm (revolutions per minute), on the disks they use the SAS interface does at speeds of between 10,000 and 15,000 rpm, substantially improving the final performance.

Another major difference between SAS and SATA drives is the high price-per-gigabyte capacity ratio since a 15,000 rpm and 900GB SAS disk can cost around € 420 (€ 0.466 / GB) while that a 7200 rpm and 1 TB (1024 GB) SATA disk is currently around 45 euros (€ 0.044 / GB).

Without taking into account the enormous price difference, both systems are very evenly matched in terms of capacities since, as already mentioned, the storage technology used for both interfaces rises on the same base, being able to find disks of up to 12 TB with SATA or SAS interface.

With a higher transfer rate, SAS disks duplicate the cache of SATA disks, from 64 MB to 128 MB. In this way, the buffer is always ready to send information, and hybrid cache systems are sometimes used in which, in addition to traditional cache memory chips, NAND memory is also used to speed up the sending of data.

In SAS drives data is the most important, so these SAS disks have better protection systems against data loss making them more secure and reliable.

The connectors of the SAS and SATA drives are very similar physically, although there are some differences between them so that they do not lead to mistakes when connecting them so that you can connect a SATA disk to a SAS connector, but you will never be able to connect a SAS in a SATA.

The compatibility of SAS with SATA and reverse incompatibility has a very simple explanation: to allow companies to amortize the units and SATA storage systems they already had - whose investment can be hundreds of thousands of euros depending on the size of the company - although this means less performance, while it makes no sense to connect a high-performance SAS to a SATA connector that limits its performance to a quarter of its capacity.

SATA or SAS what interface is better?
Speaking in terms of better or worse is not the most appropriate when talking about connection interfaces, as it would be like comparing a Formula One with an off-road vehicle. Formula 1 has no rival in the circuits, but it does not make sense out of them, while the SUV will not have a good result in circuits, but you can use it on any terrain. Depending on the use that will be given it will be more appropriate to use a SAS or SATA interface.

If what you have in mind is to set up a home server or for a small business, perhaps a SATA based storage system is the best option.

The SATA interface allows you a more than enough transfer rate and you can connect multiple disk drives on your server to get a considerable amount of storage space.

One of the great advantages of the SATA interface is that it is widespread in the domestic environment, so it is easy to find motherboards, hard disks and SSD drives that use this connector at a price very affordable for any user or small business.

That way, mounting a small server at home or in the office will be very easy and you can even use components you already had and, if you need an extra performance, you can choose to add an SSD to your server, or a unit especially designed for servers if what you need is greater reliability for your data.

Because the SAS interface provides greater scalability, increased data security and increased performance, they are ideal for enterprise servers where they must be operational 24/7 365 days a year, as they are the only ones capable of supporting that workload efficiently and with a low failure rate.

SSD with SAS interface, the technology of the future
The advancement of SSD technology is unstoppable and while in the field of domestic consumption manufacturers optimize the production processes to offer greater storage capacity at a lower price, in the professional field manufacturers strive to deliver the highest performance offered by the SSD and join it to the virtues of the SAS interface.

The first SSD units with a SAS interface can already be found on the market, but there is still a long way to go before replacing HDD drives that have so far monopolized this area. storage systems.

However, at the pace of manufacturers' developments, it will not be many years before SAS-based SSDs are more affordable, which will mean the definitive take-off of the currently standardized SAS-4 standard, which will double the transfer rates offered by the SAS interface.

This new increase in the transfer rate is quite logical considering the challenges for the exchange of information that implies the arrival of 5G and the standardization of fiber optic connections in homes.