Characteristics of SSD and HDD drives - what affects the read and write speed. Constant write speed to disk

Greetings, Dear Reader!

I will present what I myself have been convinced of in practice, having tested several dozen CD / DVD discs in different modes of recording speed.

The manufacturer of the disc tests it. One of its elements is to conduct read / write operations at different speeds. After comprehensive testing of samples, among other things, the recommended range of recording speeds is determined (example: 4x-16x). Thus, the most optimal mode of operation of the carrier is determined.

However, when recording, the user can select any possible speed from the range indicated on the media.

So, the statement that “the lower the write speed, the fewer errors”, is justified, but not always true.

Sometimes it becomes much worse from a decrease in the write speed - there are 2 or 3 times more errors on the disc than if it was recorded at the maximum speed allowed for it.

The point is that it is impossible to make an unambiguous verdict. There are many brands of discs, and they all behave differently.

But what is interesting is that high-quality discs from famous companies (Verbatim, TDK, Imation, Sony) in most cases produce approximately the same number of errors (in both cases - acceptable), both at low and at maximum speeds. Of course, this is a sign of the quality of the media. Especially here I would like to note the TDK disks - which behave the most stable.

Of course, the disks of some other little-known companies do not behave so predictably. The result may differ, as they say, “from blank to blank”. Those. one disk shows the best results at low speed, while the other is identical to the first, on the contrary, it shows fewer errors at maximum speeds.

First, buy discs from reputable brands.

Second, burn the disc at a speed not higher than that recommended for this disc. The recommended maximum write speed is almost always indicated on the disc itself.

That, in fact, is all ...

As for the statement that “lower speed is better,” I want to note: this is far from always true. Long away. And not always.

In some cases, lowering the write speed can play a cruel joke, greatly increasing the number of errors on the disc.

P.S. I remind you that very soon my new project will start, which will be entirely devoted to such an important issue as information security. Details: www.oborona.info-dvd.ru .

QUESTIONS AND ANSWERS: What you need to know about burning CD-R and CD-RW discs.

1. What do you need to have to burn CDs?

You need a computer with a device called a CD-writer installed in it. This device is connected to the computer in several possible ways. Most disc drives have an IDE interface and connect in the same way as regular CD-ROMs or hard drives and are internally designed. However, there are other versions, both external and internal - with the SCSI interface, connected to the parallel port or to the USB bus.
The second necessary part for burning discs is the software. Its choice is very wide - from the most popular commercial packages from Adaptec (Easy CD Creator, Easy CD Deluxe, Easy CD Pro) to shareware programs like Nero or CDRWin.
Finally, you need a blank CD-R or CD-RW disc

2. What can be burned onto CD-R or CD-RW discs?

Traditionally, both sound and data can be recorded to discs. The data is saved on CDs in the usual form in which they are stored on the hard disk. It should also be noted that it is possible to create mixed discs, combining sound with data.

3. What is the difference between CD-R and CD-RW discs?

CD-R stands for CD-recordable, which means "recordable". This means that the information recorded on such a disc cannot be deleted from there. The main difference between CD-RW (CD-rewritable) discs is that information from them can be deleted and written again. As a result, more flexible CD-RW discs are somewhat more expensive than conventional write-once discs.

4. How much information can be recorded on a CD-R disc?

5. Why is the standard duration 74 minutes?

By all accounts, this length was chosen because the CD designers wanted a format that would fit Beethoven's Ninth Symphony. They determined which diameter to use, and the length of some performances resolved this issue.

Burned discs can be used on the following devices:

Consumer CD player Given that consumer CD players predate CD-R recorders, there is no guarantee that all recorded music CDs will play in audio players. However, for best results, it is recommended to use CD-R discs, as their specification is much closer to traditional music discs than CD-RW discs. DVD-ROM drive or DVD player The vast majority of DVD players and all DVD-ROM drives (with the exception of early examples of these devices) are able to read information from CD-R and CD-RW discs. CD-ROM drives

All modern CD-ROM drives are excellent at reading both write-once and CD-RW discs. The nuances exist only with old drives, which in some cases do not read CD-R discs, or read these discs, but do not read CD-RW discs. If your old floppy drive is marked as having the Multiread function, then this means that with its help you can cope with this task. A good indication that a drive is capable of handling recordable discs is the read speed of that drive. If the speed is 24 and higher, then as a rule such a drive is quite suitable for working with CD-R and CD-RW discs.

7. Why does the reflective side of discs have different colors?

Different CD companies have patents for the different chemistry they use to make the CDs. Some companies make their own discs, some simply license their technologies to them. As a result, the reflective side of the CDs is colored differently. There are CD-Rs of the following composition combinations: gold / gold, green / gold, silver / blue, and silver / silver, and their many shades. The visible color is determined by the color of the reflective layer (gold or silver) and the color of the dye (blue, dark blue, or colorless). For example, green / gold discs are composed of a gold reflective layer and blue dye, so the disc is gold on the label side and green on the recording side. Many have come to the conclusion that "silver" discs are made of silver, and based on this assumption, have tried to speculate about the reflectivity and durability of the media. Until the manufacturer's representative makes a statement about the actual composition of the disc, it is unreasonable to assume anything specific. Some CDs have an additional coating (such as Kodak's "Infoguard") that makes the CD more scratch resistant, but does not affect the way the information is stored. The top (label) side of the disc is the most important thing to worry about, since this is where the data "lives" and is the easiest to damage on a CD-R. To protect the disc from scratches allows gluing a round CD sticker over its entire area. CD-RW discs have a completely different structure. The data side (as opposed to the label side) is a silvery dark gray that is difficult to describe. You can also give a short list of which companies produce these or those discs:

Taiyo Yuden produced the first green CDs. They are now also manufactured by TDK, Ricoh, Kodak, and probably a few other firms.

Mitsui Toatsu Chemicals (MTC) produced the first gold CDs. They are now also manufactured by Kodak and possibly others.

Verbatim produced the first "silver / blue" CDs.

Many CD-R brands (such as Yamaha and Sony) are OEM versions of one of the major manufacturers. Generally speaking, it is difficult to determine who is producing what, as new factories are built and sellers can change suppliers.

8. What do the speed numbers (for example, 6x4x32) mean in the parameters of CD burners?

Conventional audio players play music CDs in 74 minutes. This speed is taken as the basis for measuring the speed of playing and recording CDs and is called single speed (1-x). A one-shot speed corresponds to a transfer of 150 Kilobytes per second. A CD-ROM drive with 2x speed (2x) transmits data at 300 Kilobytes per second.

Three numbers in the parameters of CD-writers means the speed at which this device can write CD-R discs, CD-RW discs and, accordingly, read these discs.
For example, 6x4x32 means that this device writes CD-R discs at 6x (900 KB / sec), writes CD-RW discs at 4x (600KB / sec) and reads any type of CD at 32-x (4800 KB / sec)

9. What are the recording formats for CD-R discs?

This is the most difficult question to answer, given that a wide variety of CD formats have emerged over the past few years, while there are still historical formats that have existed for a long time and are used in specialized applications. Below is an overview of the main formats:

Music discs (Audi o CD) or CD-DA or "Red Book"

To burn regular music CDs, you need the disc to be recorded that complies with the CD-DA standard. When recording, files of the standard type WAV (or AIFF - Apple Audio Interchange File Format) are used as a source

ISO9660 Data CD

This standard defines the form in which ordinary data is recorded on CD-R discs. This standard has many restrictions, namely - the maximum number of nested directories cannot exceed 8, file names cannot be longer than 8 characters and 3 characters are reserved for the file name extension. However, this standard is compatible with a wide variety of computers and operating systems.

The format proposed by Microsoft simultaneously with the appearance of the Windows 95 operating system. The file name length is limited in this standard to 64 characters, and this format is now supported in both Windows and MacOS and Linux. Joliet is based on the ISO9660 standard and disks, written in this format can be read on almost any computer, but filenames will be truncated to 8 + 3.

This format is strictly related to Macintosh computers. HFS CDs can only be read on this type of computer.

UDForPocket Writing

UDF (Universal Disk Format) is a radical extension of the ISO9660 standard, somewhat reminiscent of Joliet. Adaptec DirectCD software (available with Easy CD Creator Deluxe or sold separately for Mac platforms) and CeQuadrat PacketCD software, for example, allow you to burn discs in this format. UDF differs from other formats in that you can work with a CD like a large floppy disk, copying files to it using standard Windows or MacOS tools. However, this format is not suitable for transferring discs to other people, because in order to read discs of this format, they will need to install special software to read such discs.

ISO 9660 Rock Ridge

An extension of the ISO9660 standard used exclusively in Linux and UNIX operating environments.

ISO Level 2

Slightly modernized ISO9660 format, simplified in terms of limitations. For example, the file name is limited to 31 characters in length. However, the low level of compatibility of this standard does not allow it to be applied as widely as, for example, the Joliet format.

VideoCD or VCD or White Paper

The VideoCD format was developed in the mid-90s and was targeted for use in a device such as the Philips CD-I player. VideoCDs contain video and audio compressed according to the MPEG1 standard. Despite the fact that Philips CD-I player has not been produced for a long time, these discs can be used on the vast majority of DVD players, if they support reading CD-R or CD-RW discs.

8. What format should I use if I want to….

…. share data with friends who are using an operating system similar to mine?

Everything is simple here. Windows users should use Joliet format, Mac users HFS format.

…. share data with people who use different operating environments and platforms?

For maximum compatibility, it is recommended to use the ISO9660 format. However, if you need to store long filenames on disk, then you should try using the Juliet format. Modern Macs and most operating systems now have the ability to read discs written in this format.

…. listen to music on a regular audio player?

Then you should burn the disc in CD-DA format, which will provide the greatest level of compatibility with your audio player.

10. How do I burn mixed content discs?

There are two possibilities to burn such discs:

Mode I- when using this format, data is recorded at the beginning of the disc (in any known format), followed by the recorded audio tracks. If you need to combine sound and data, then using this mode will provide the necessary level of compatibility with various devices and operating environments.
CD-XA (Mode II)- this mode differs from the previous one in that data and sound can be recorded in random order. However, this flexibility negatively affects the compatibility of the burned discs.

11. What is a multisession CD?

This technology allows you to add data or sound to a disc on which something has already been recorded until the "closing" of the disc is performed. This was very relevant in the early 90s, when the cost of an empty CD-R disc reached $ 12, CD-RW discs did not exist, and hard drives were small.

Discs recorded with this technology have some compatibility problems and therefore it is not recommended to use it without good reason. The UDF format makes this technology unnecessary; With Direct CD and similar software, you can record data without worrying about compatibility. If you need to transfer the disc to other people, then simply burn it in Joliet format at a time.

12. What is "closing" a disk?

"Finalizing" a disc means that after performing this procedure, nothing on that CD-R disc will be possible. If you never use the "multisession" feature, then it makes no sense for you to think about it, because the disc will close automatically after the information is written to the disc. Many older CD-ROM drives and audio players have problems reading unclosed discs, so it makes sense to "close" the disc for better compatibility.

If you want to write something to a "closed" CD-RW disc, simply execute the "clear" function and you can write data to that disc again. If you are using the UDF format, there is no concept of "closing" a disk in the traditional sense of the word - just copy and delete files from such a disk as from a simple floppy disk.

What is CD-R writing speed.

The term "write speed" defines how quickly data can be written to a CD-R disc. Marking 2x, 4x, 6x, 8x, 12x, 16x, 20x, 24x, 32x, 40x, 48x shows how many times faster the device writes data compared to the single-speed reference. One speed is understood as a data transfer rate equal to 150 Kb / s. Thus, the marking "2x" means that data can be written at a speed of 300 Kb / s, respectively "8x" - 1.2 Mb / s, and "16x" - 2.4 Mb / s. Please note that the actual speed may vary depending on the selected recording format, since data is recorded in the 2 "048 bytes per block mode, and the audio information in the 2" 352 bytes per block mode.

Therefore, the actual recording time of one full disc may differ slightly depending on the format. Typically, CD-ROM drives are labeled with a single digit representing the maximum speed at which data can be read. In this case, the fastest format for reading is indicated - CD-ROM Mode 1, moreover, moreover, when measured on the outer perimeter of the disk. The marking of CD recorders contains three numbers: the first is the writing speed of CD-R discs, the second is the rewriting speed (CD-RW discs), and the third is the reading speed. Accordingly, marking 16x10x40 for a CD recorder means that it is capable of writing CD-R discs at 2.4 Mb / s, CD-RW discs at 1.5 Mb / s, and reading discs at 6 Mb / s. If the marking consists of two numbers, it means that such a drive cannot work with CD-RW discs.

Disc recording modes:

disc-at-once (DAO) disc burning:

This is a recording mode when a disc is recorded immediately from beginning to end, without interruptions. Those. the laser beam turns on at the beginning of the disc recording, and turns off only at the end of the recording. First, special information is written to the disk, marking the beginning of the recording (lead-in), then the data itself, and at the end the final information (lead-out). As a rule, the DAO method is preferable if the disc is later transferred to the factory for replication, and the recordable CD-R is the master disc. Recording in DAO mode allows you to avoid bundles of input (run-in) and output (run-out) blocks, which are associated with multisession recording by mastering equipment and make the disc unsuitable for making a matrix from which cd replication will be performed.

track-at-once disc burning (TAO):

The TAO recording mode allows you to record a disc not immediately from beginning to end, but in several passes: initially, you can record one audio track (track) on a disc, then another, and so on. Accordingly, as many tracks are recorded on the disc, the laser beam will turn on and off as many times during recording. The switching on and off of the laser is perceived by sound players as a pause between tracks lasting 2 seconds. It should be noted that an audio disc recorded in this way can only be read on a regular CD player after the table of content (TOC) has been written. After TOC has been recorded, it is not possible to add tracks to the disc.

session-at-once disk write (SAO):

The SAO recording mode is usually used when recording the CD-Extra format, a format that combines audio part (CD-DA format) and software part (CD-ROM format) on a disc. When recording in SAO mode, the laser beam turns on at the beginning of recording the audio part, turns off at the end of recording tracks, then turns on at the beginning of recording a part of data and turns off at the end of the recording. The TAO mode is also applicable for preparing CD-Extra format discs. In this case, during the recording of the audio part, the laser will be turned on / off as many times as there are tracks on the disc.

multisession recording mode

Ultisession is a recording mode that allows you to add new information to a CD, that is, add new information to the previously recorded one. Each session contains a record of the beginning of the session (lead-in), then the data itself and the final information about the session (lead-out). Unlike disc-at-once recording or injection-molded CD, there can be up to 99 such sessions on one disc. When recording in multisession mode, information about the structure of previous recordings is copied to the new one session and can be fixed. Thus, when recording in multisession mode, the user can destroy information about the structure of already unnecessary or obsolete records without including it in a new table of content (TOC - table of content). This means that it becomes possible to "erase" unnecessary information from the CD, although in fact, it physically continues to remain on the disk and can be restored using special software. The disadvantage of the multisession mode is that disk space is wasted, since it separates one session from another. About 13.5 MB is lost each time (6 "750 blocks). The more sessions recorded on the disc, the more space is wasted for the session separators. In addition, some older CD-ROMs (usually released before 1994) cannot read multisession discs. hence

Of course, this is the main difference between the two, but not the only one.

Types of computer memory

Computer memory is where data is stored. The memory is divided into ephemeral(like random access memory or RAM), which only retains data as long as the computer is running, and permanent(non-volatile) that retains data even after power off.

It can also be divided by device, or rather by type. Can be distinguished magnetic media(e.g. hard drives HDD, SSHD), optical, semiconductor and flash memory.

Differences between HDDs and SSDs

Media design

The main difference that first comes to mind is the internal structure.

Hard disk drives HDD are magnetic storage media. To read them, a special, movable head is used, which moves along the circular magnetic plates used for storing data, and thus searches for files.

SSD media are classified as flash memory built from NAND Flash cells only. This allows you to read and write files on the SSD much faster - all due to the fact that reading occurs without the participation of moving elements. Moving parts must arrive at the location of the file and cannot be present in multiple locations at the same time (which further slows down reading or writing multiple files).

Loudness during operation and resistance to damage

Moving elements are also responsible for the noise generated during the disc operation. Deprived of these moving parts, SSDs run silently. In addition, they are also more resistant to damage (again this is due to the lack of mechanical parts that can move, for example, in the event of a fall).

The AHCI protocol was created for HDDs at a time when faster storage media was never expected. Later SSDs had huge potential in terms of data flow, however, it was severely limited by the legacy protocol.

For new fast hard drives, a new NVMe protocol has been created. Its capabilities are shown in the table below:

Firstly

What is CD-R writing speed?

The term "write speed" defines how quickly data can be written to a CD-R disc. Marking 1x, 2x, 4x shows how many times faster the device writes data compared to the single-speed reference. A single baud rate refers to a data transfer rate of 150 Kbps (for Form 1, normal for CD-ROMs) or 172 Kbps (for Form 2, normal for Video-CDs). Thus, marking 2x means that data can be written at a speed of 300 Kb / s, and 4x - 600 Kb / s. Please note that the actual speed may vary depending on the write modes (Form 1, Form 2, CDDA), since, for example, Form 1 data is written in 2048 bytes per block mode, and CDDA audio information in 2352 bytes mode. per block.

Usually in the description of CD-ROM drives, a number is indicated that indicates at what speed the data can be read (for example, 24x for Acer 624A). CD recorders are marked with two numbers. The first is the write speed, the second is the read speed (for example, 4x8 for a Panasonic 7502B CD recorder). If the marking consists of three digits, it means that such a drive can also work with CD-RW discs, the possible write speed of which is the second digit in the marking.

and secondly:

There is an opinion that it is better to burn discs at 2x and 1x, and not at 4x. Is it true?

This makes some sense. Physical and chemical processes occurring during the recording of CD-R discs give a better result (deeper and more readable marks on the active surface) at twice or less high write speed, due to the steeper slope of the modulation fronts of the laser beam and the longer duration of its exposure per unit (pit) of the information surface, as well as a more favorable temperature regime for recording (at high write speeds, due to the high power of the laser, local heating of the active layer of the disk is observed, that is, the track does not have time to cool down in one revolution of the disk, transferring heat to the adjacent turn of the track, to which recording is in progress, resulting in a concentric zone of increased disc temperature that will reduce recording quality). Modern recording devices and discs are focused on recording speeds of 2x, 4x, 6x and even 8x, however, such speeds are needed to increase the device's performance during mass replication of discs, and do not contribute to the recording quality at all.

In general, discs with a silver layer (Metal Azo) are better suited for recording at high speeds than discs with a gold layer, due to the higher thermal conductivity of silver, so they can be recommended for those who like to print commercial runs at 4x or more. For audiophiles, it is recommended to use discs with a phthalocyanine layer for recording audio CDs (CDDA) and record them at single speed - this ensures the highest recording quality and its durability.

maybe these fakies are a little outdated, but in my opinion just the topic!