Comparison QNAP TS-251A RAM 2 GB vs QNAP TS-253B RAM 4 GB

This item characterizes the maximum capabilities of the device for connecting drives. This way you can understand how much maximum memory can be added to the NAS server.

The number of PCI-E slots provided in the design of the NAS server.

PCI-E is one of the most popular modern interfaces for connecting internal components to a computer motherboard. Specifically, in NAS servers, it can be used, in particular, for wireless adapters and SSD drives; in the latter case, PCI-E allows higher speeds than SATA and fully realizes the potential of solid-state memory. And the number of such connectors corresponds to the number of PCI-E components that can be simultaneously installed in the server.

Note that the PCI-E connection can use a different number of lines (1x, 4x, 16x), and for normal operation it is necessary that the slot on the "motherboard" has no fewer lines than the installed component. In fact, this means that a component with a 1x connector will easily fit into any slot, but with a larger connector, the connection should be specified separately. However, in the case of NAS servers, even PCI-E 4x capabilities are rarely required, not to mention 16x.

The number of USB 3.2 gen1 ports provided in the design of the NAS server.

USB connectors are used in computer technology to connect various external peripherals. In the case of NAS servers, we are most often talking about external drives — flash drives, hard drives, etc. In this way, you can transfer information from an internal drive to an external one (for example, for backup purposes) or vice versa, and even expand the total working volume of the server . In addition, on models with a VGA output (see below), a keyboard can also be connected to USB, and on models with a print server function (see "Software Features"), respectively, a printer. For added convenience, the USB connector can be placed on the front panel (see below).

Specifically, USB 3.2 gen1 (formerly known as USB 3.0 and USB 3.1 gen1) is the direct successor to USB 2.0 and is the most common USB standard today. This version provides data transfer rates up to 4.8 Gbps, as well as a fairly high power supply. At the same time, such connectors are backward compatible with peripherals using USB 2.0.

The number of USB-C ports provided in the design of the NAS server.

Like the more traditional USB 2.0 and USB 3.2 gen1 (see above), connectors of this type are mainly used to connect external peripherals: drives for exchanging data and/or expanding the working volumes of a NAS server, keyboards for direct control, etc. However, USB-C has its own specifics. First of all, this is the design of the connector: it has small dimensions (slightly larger than microUSB) and a two-sided design (the plug can be connected on either side, unlike previous standards). The second feature is that other interfaces can be implemented through the physical USB-C connector — for example, Thunderbolt, which also has a video output mode. However, the main format for this type of port is still the connection of USB devices; in terms of capabilities, such a connection most often corresponds to USB 3.2 gen1 (at speeds up to 4.8 Gbps) or USB 3.2 gen2 (up to 10 Gbps).

For added convenience, the USB-C connector can be placed on the front panel (see below).

The presence of an HDMI output in the NAS server; either the presence of such a connector itself or its specific version can be indicated here.

HDMI is a digital interface specifically designed to carry high-definition video and multi-channel audio. This is the most common of these interfaces, most modern monitors, TVs, home theaters, projectors, etc. have this type of input. Thus, even in such a specific technique as NAS servers, such outputs have several applications. The first option is to connect a monitor to monitor the parameters of the server; some devices at the same time allow you to connect keyboards / mice and control the server directly, like a regular computer. The second option is to use the NAS server as a media centre to broadcast movies and other content to a TV, home theater, etc.

The specific functionality of HDMI should be specified separately. As for the versions, the following options are relevant today:

— v 1.4. Relatively old (2009), but still quite widely used version. Supports resolutions up to 4096x2160 (at 24 fps), as well as frame rates up to 120 Hz, which allows you to play 3D content as well. It is found both in the original version and in improved versions v 1.4a and v 1.4b — they have advanced features for working with 3D.

-v 2.0. Version released in 2013. The increased bandwidth compared to its predecessor made it possible to provide full support for 4K video (at frame...rates up to 60 Hz), as well as multi-channel audio up to 32 channels and 4 streams over a single cable. HDMI v 2.0 did not originally support HDR, however this feature was introduced in the v 2.0a update and was improved and expanded in v 2.0b. With all this, old cables, originally designed for version 1.4, are also suitable for connecting according to this standard.

— v 2.1. Standard introduced in 2017. Also known as HDMI Ultra High Speed, bandwidth has increased so much that it is possible to transmit video at resolutions up to 10K at 120 frames per second. Note that to use all the features of this version, you need cables that were originally created for it (although the functionality of earlier versions will be available when connected via a regular cable).

In conclusion, we note that different versions of HDMI are mutually compatible, however, the signal transmission capabilities in such cases will be limited by the characteristics of the older and slower standard.

— Web server. Ability to use the device as a Web server. It is on servers of this type that the Internet in its current form is built: the user's computer sends a request to a web server through a browser and receives a response in the form of a page, picture, video / audio stream, etc. Accordingly, the presence of this function in the NAS allows you to view its contents in the form of web pages using a regular browser — roughly speaking, "walk through the server, like on the Internet." In this case, the device can be used not only as a local resource, but also as a web host — for example, host the company's official website on it.

— FTP server. FTP is an abbreviation for File Transfer Protocol, i.e. file transfer protocol. This feature allows you to use the NAS server as a shared data storage: users can "upload" their own files to storage and download them from there. FTP tools provide ample features for configuring access to server content — for example, you can set restrictions on writing information to individual users or to individual folders, close part of the content with passwords, etc. Due to this, this protocol is much more convenient for working with individual files than the HTTP used in web servers (see above). Therefore, if you plan to create shared storage on the network, it is advisable to have a NAS with FTP server function.

— Print server. The print server feature makes it easy to share the same printer among network users. The printer is connected to the NAS, usually via a USB interface (see above), and the NAS serves as an intermediate link: it receives print jobs from users and sends them to the printer. Additional print server features can include sequencing optimization, local job storage (document will be printed even if you turn off the computer from which the job was sent), deletion of "overdue" jobs, and even accounting for the number of pages and remaining consumables. Using a NAS with a print server function is often more convenient than connecting a printer through one of the regular computers on the network.

— Multimedia (DLNA, iTunes, uPnP).... NAS server supports various functions related to the exchange of multimedia content. For example, DLNA (Digital Living Network Alliance) is a standard, one of the functions of which is the general access of various network devices to video, audio and photos stored on a local network; while streaming is also supported. The iTunes player has multimedia networking features similar to DLNA, but was created specifically for Apple electronics and is used primarily in it. uPnP (Universal Plug and Play) is a technology that facilitates the automatic configuration of local networks, including to share content. A server with multimedia functions should be looked for in the first place if the ability to work with streaming video / audio is important for your local network.

— Transcoding. A function that allows you to convert audio and video materials from one format to another directly during playback. In other words, the file on the NAS server is stored in one format, and it can be sent to an external device in another, the server itself will provide the conversion. It should be taken into account that the set of supported formats and general transcoding capabilities may be different (in particular, the maximum video resolution is inevitably limited); these nuances should be clarified in each case separately. However, this function anyway significantly expands the possibilities for playing multimedia content and reduces the likelihood of compatibility problems.

— BitTorrent client. The presence in the device of its own torrent client or other data exchange protocol (HTTP, FTP, etc.). This feature allows you to work with file-sharing networks, which are built on the principle of "everyone's own server": the downloaded information is not on a separate computer on the network, but on the computers of the same users. At the same time, the same file can be opened for download in several places and the torrent client simultaneously downloads different parts of it from different sources - this significantly increases the speed. Using a torrent client on a device is convenient in two ways. Firstly, it allows you to offload the main computers of users - an important advantage, given that the torrent client can consume a lot of resources, especially with an abundance of simultaneous downloads / distributions. Secondly, network equipment tends to stay on at all times, allowing downloads and uploads to continue even when users' PCs and laptops are turned off. However, it should be taken into account that despite the presence of such functionality in devices, the open placement of content in torrent networks can violate copyrights. Therefore, use torrent clients in compliance with legal regulations.

— Mail server. Ability to operate the NAS in server mode for e-mail processing. On such a server, you can create mailboxes in the format [user]@[company_name].com, it works as a storage for incoming letters and as a forwarding service for outgoing ones. Additional features may include automatic redirects, spam protection, custom filters, and so on. Having this feature is indispensable if you need a corporate email system: your own internal storage is more reliable in terms of security than external email services, and the ability to create unique email addresses can also come in handy.

— Database server. As the name implies, this function is useful for creating databases — systematized arrays of information designed to be accessed and processed from a computer. It is usually implemented through support for the SQL language. Its peculiarity lies in the fact that the network user does not need to know the specific location of the information in the database — it is enough to issue a request, what kind of data needs to be obtained, and the server itself searches for it. This is very convenient when working with large volumes of information, while high power is not required from user computers — the main load falls on the server.

— Surveillance server. A set of software tools that allow you to use the NAS as a storage for video recordings from surveillance cameras. Features of video storage may be different. For example, in some servers, a certain part of the working volume of drives can be allocated for this, and when it overflows, the oldest records are automatically deleted, freeing up space; in others, deletion is carried out not by volume, but by date — for example, materials are stored for a month, then deleted. Both the volume and the shelf life, usually, can be set by the user himself. And some models with a VGA output (see above) can also be used as live surveillance systems — the image from the cameras is displayed on the monitor in real time, which can be useful, for example, for organizing security. The specific features of the operation of the NAS in the video server mode may vary from model to model, this point is best specified according to the manufacturer's official data.

— Backup. The backup function is designed to create a backup copy of data (so-called backup) in case of loss or damage to information on the primary media. Backup can be done to the built-in or external drive, and even to another device over the network. To facilitate this task, many developers create various specialized software tools; in this case, it is assumed that the NAS server supports one of these tools. Also, software capabilities can be supplemented by hardware ones — for example, a separate quick copy button.

– ZFS file system. An advanced file system that uses a transactional copy-on-write model. Active data is never overwritten - ZFS places the new block in a different location on disk and updates the metadata, which allows you to write a link to the new block of information and save older versions of the data. The key features of ZFS are snapshots (immutable copies of the file system made on the fly), advanced compression algorithms, and a built-in deduplication function. ZFS is also one of the most advanced file systems in terms of security.

— DDNS. Short for Dynamic DNS — "dynamic DNS". This feature allows you to assign a permanent domain name to a device with a dynamic IP address. A domain name is the name of a device on the local network or the address of a site on the Internet (for example, m.ua or e-katalog.ru). An IP address is service information in the form of a digital code; it is thanks to her that network equipment can find the desired device and issue the required data from it. Actually, IP is the primary network "coordinates"; however, remembering addresses as a sequence of numbers is quite difficult, so domain names appeared — they are much more convenient for a person. Both on the Internet and in local networks, the connection between a domain name and an IP address is responsible for the so-called DNS servers: for each domain in the database of such a server, its own IP is registered. However, for technical reasons, there are often situations where the NAS server has to use a dynamic (changing) IP; accordingly, in order for information to be constantly available on the same domain name, it is necessary to update the data on the DNS server with each IP change. It is this update that the DDNS function provides.

— Integration with. A software tool that makes it easy to integrate a NAS into an existing domain (computer network area). Each domain has a so-called a controller is a server that stores information about users, primarily logins, passwords, and access rights. When connecting a NAS with the integration function, all these settings can be automatically imported, so that all users have the same access rights to the contents of the NAS as to all contents of the domain. This saves the administrator the hassle of creating and configuring separate accounts (which can be quite a hassle on large networks).

— Airplay. NAS server support for AirPlay technology. This is an Apple proprietary development, originally created for wireless broadcasting of audio and video content from Apple technology to TVs, audio systems and other playback devices; however, nowadays, the role of the transmitter can also be performed by electronics from other manufacturers. This is what we are talking about in this case: AirPlay support allows you to broadcast video and/or audio content stored on the server from the NAS server to external devices. To do this, the NAS and the AirPlay-compatible signal receiver must be on the same network, and the signal receiver must be connected via Wi-Fi. Such a broadcast is usually controlled either through a browser on a computer, or through a proprietary application on a mobile device that plays the role of a remote control. Also note that, in addition to the original AirPlay, compatibility with AirPlay 2 can also be provided — this is an improved version of this technology, which introduced, in particular, the ability to work in the multiroom format (simultaneous broadcast of different audio tracks to different devices within the network).

— Chromecast. NAS server support for Chromecast technology. This technology, developed by Google, is in many ways similar to the AirPlay described above: it is intended primarily for broadcasting audio and video to playback devices wirelessly. Accordingly, the use of Chromecast is almost the same: a NAS server with this function can broadcast the content stored on it to a TV, projector, audio system, or other compatible playback device connected via Wi-Fi to the same local network. Management is also most often carried out through a web interface or using a mobile application.

The model and specifications of the processor installed in the NAS server. The speed of the device largely depends on these characteristics, primarily the clock frequency. However, in fact, this parameter is often more of a reference value: simple everyday tasks (say, FTP and print servers, see "Software Features") do not require high computing power. But for working with extensive databases (see ibid.), a “faster” processor may be useful.

The number of cores provided in the processor of the NAS server.

Initially, each core is a computing module designed to execute one sequence of instructions. Accordingly, multiple cores make it possible to work simultaneously with multiple data streams, which improves flow Rate - especially when processing multiple tasks at the same time. Also, in modern CPUs, multithreading technologies are increasingly being used, which allow loading each core with two sequences of commands at once. During the inevitable pauses in the execution of one of the threads, the kernel does not idle, but works with another sequence. As a result, the total number of threads in such processors is twice the number of cores; this scheme of work even more noticeably improves flow Rate.

It is also worth remembering that the overall capabilities of the processor are highly dependent on a number of other characteristics - microarchitecture, clock speed, support for special functions, etc. This means that a large number of cores does not in itself guarantee high flow Rate: for example, an inexpensive mobile processor on 4 cores may well be "weaker" than an advanced desktop chip with only 2 cores. However, if we are talking about a CPU with a similar specialization and clock speed, then a solution with a large number of cores ( 6 cores, 8 cores, or ev...en more) and multithreading support usually turns out to be more productive.

Clock speed of the processor installed in the NAS server.

The clock frequency is the frequency of the built-in oscillator, according to which all operations performed by the processor are synchronized. The higher this frequency, the more operations per second the CPU can perform and the easier it is to provide high computing power in it. However, note that the actual speed of the processor depends on many other features — the number of cores (see above), microarchitecture, volumes of the built-in cache memory, etc. So, only chips with similar characteristics and purpose can be directly compared by clock frequency ( desktop/mobile) and price category.