Permanend data storage is a device that can store data for a long period of time. This is the most most important feature of any computer. The first storage devices used in computer industry ware optic tapes or perforated cards. Later was invented the floppy disks. These devices are no longer used and are replaced by CD-ROM, DVD-ROM and BD (Blue Ray Disk).

Magnetic Tape

Magnetic tapes have been used as external devices from the early days of PC. First tapes use to be like sound tapes or video tapes but a little bit more robust. These tapes are DAT tapes. After this several standards of tape storage have been created to increase the capacity and reliability.

DLT Tape

Two base types are most important: DLT (Digital Linear Tape) and SDLT (Super DLT) with several variations of different capacity. Usually the variantions are not companible to each other.

Tapes media is guaranteed to store data for 30 years and have a specific collor that indicate the format. For example in the next picture we have Super DLD Type 1 (Dark Green).

There are several companies that produced tapes of different type and capacity specific to a device. So you can’t buy a device from one manufacturer and tape from another. A tape drive is usually using SCSI protocol and is not suitable storage for a desktop computer.

LTO Tape

The latest standard for backup tape is LTO. This standard allow tapes to be interchanged between devices so you can use a Sony tape into a HP device for example.

LTO (Linear Tape Open)

The LTO standard has evolved from LTO I to LTO VII. The LTO VI allow a large capacty of 6.25 TB. This tape is for about 25 USD. Today the standard LTO 6 tape has a native capacity of 2.5 TB uncompress. The LTO 7 magnetic tape has reach capacity of 6 TB uncompress and 15TB with compression. HP has push the fronteer LTO-7 Ultrium to RW standard up to 15 TB.

What is CD DVD and BD?

In next section I will present a series of Compact Disks. This can be confuzing if you are not familiar with notation. When you buy you must know what it is right? So I will try to explain some of the notations and what advantages one disk has over another.



Most comon disk is DVD. This can be simple or double layer or double side. There is a difference. Double layer do not have to be turn over to write on it. Double side can be written on both sides but can’t have a label written on any side. That means you must turn over the disk to read the other side. DVD-R can be witten once while DVD+RW can be written multiple times. However it need to be erased before you can write on it second time.


Next disc store up to 9.4 GB and can be read and write very fast by using a DVD-RAM capable device. Not all devices know how to handle DVD-RAM standard. This disk is a random access disk and is organized different then the DVD-RW. It can be written multiple times but has random access exactly like a normal hard disk. Is organized in sectors and you can write instandly small number of files at a time.


Blue Ray Disk or BD can be a good data storage. Blue Ray starts from 25 GB, 50 GB up to 100GB. You can find internal or external devices for 50$ up to 150$ and you can use these devices to record also DVD if is a combo device.

BD (Blue Ray Disk) is inexpensive and easy to find in bulk. The BD-RE storage is read write storage and can be used for backups. In the picture below you can see a disk box for (BD-R) that is not revritable but can be burn only once and read multiple times.


I think this is kind of magnetic-optic disk. Verbatim M-Disc™ optical media is the new standard for digital archival storage. Unlike traditional optical media, which utilize dyes that can break down over time, data stored on an M-Disc is engraved on a patented inorganic write layer — it will not fade or deteriorate.

Take chare handling a DVD !!! CD, DVD and BD are sensible to light dust and scratches therefore must be enclosed in a box or envelope. Do not put the disk face down on a desk or on paper. Handle the disk careful face down and do not touch with your fingers the active side. After you finish using the disk put it back into the box.


What is HDD?

The most successfully storage device and the most popular is today the hard drive. HDD device or hard drive is an internal or external box that contains mechanical parts that are used for storing large amount of data. These devices are very successful due to rapid access to read or write information. These devices are designed for desktop PC, Servers or Laptops. There are 2 standard sizes: 3.5″ and 2.5″

Internally these devices are using one or several disk platters that are mounted on a spindle. The patters are easy to magnetize and demagnetize using a small coil mounted on a moving head that is reading or writing data. Some HDD are using a single disk some other are using one 2 or 3 platters on the same axis but new disks can have upt to 8 platters to increase the capacity.

Depending on the number of disks and the spinning speed the HDD can be faster or slower. The spinning is measured in RPM (rotation per minute). For example a 15000 RPM or 10.000 RPM is used for fast responsive server side HDD while 7500 RPM is used for desktop computer while 5000 RPM disks are used for laptop computers.

The capacity of HDD is measured in GB (GigaByte) or TB (TeraByte). 1 TB = 1000 GB. One Byte = 8 Bit.Usually a laptop is using a single HDD of small capacity (GB) while desktop or servers can use 2 or more HDD of large capacity (TB).

Because HDD has moving parts it generate heat, vibrations and is subject to mechanical and thermal degradation. Today you can find HDD of large capacity up to 10 TB for servers using SATA or SAS interface or for NAS storage.

NAS Storage

A NAS storage that is a box in fact a computer that is dedicated for large storage capacity.

In the picture above you can see: 12 bay (8+4) NAS/iSCSI IP-SAN. Intel Skylake Core i5 3.6 GHz Quad Core, 16GB RAM, 10G-ready device. You can find this device for $2300. This is just an example for new technology not a recommendation of mine. Feel free to investigate careful for your NAS or external drive solution before you buy.

What is SSD ?

There is now a new disruptive technology available on the market for storing data. This is called Solid State Disk (SSD) or SSD card accelerator. An SSD is a hard drive that does not have moving parts. Is like a permanent memory storage shaped as a hard drive for convenience.

SSD has a lower capacity (128 GB, 256 GB, 500 GB) and is very appreciated as laptop storage or desktop boot drive where you can install the operating system to improve PC performance.

The SSD read and write fast but delete operation is a little bit slower. After multiple read and writes the disk is loosing some of the performance. For this there is a optimization software that can run from time to time to keep performance up.

Enterprise class SSD

Due to it’s performance SSD is promoted now for enterprise class server. In the picture below you can see top of the line SanDisk SSD. Up to 500/500 Mb/s read write speed and capacity up to 4TB. This SST has a SAS interface that is now common for Enterprise HDD.

What is ReadyBoost?

You can improve Windows performance using a small SSD as secondary disk. You can use up to 32 GB of SSD disk to be used as cache using windows ReadyBoost technology.

For this you select an empty SSD and format as NTFS. Then you use disk/properties/readyBoost to set-up the disk for chache. This may improve performance only if your primary disk is not already SSD.


If you have a small SSD for Linux this is great. You can install / (root) on SSD format using EXT4 and use /noatime option for mounting. Then you have a very fast boot time.

If you have more then one HDD in your computer or you use a RAID arry then you can use SSD to store /boot partition (up to 200 ~ 500 mb). This can be formatted EXT3 or EXT4.

Use secondary disk or RAID array to mount / (root) partition. This will allow you to store larger amount of data on the computer or server.


It is problematic to install boot loader for operating system on a software based RAID. Therefore usually the primary disk on Windows operating system is not RAID based.

On Linux you can have a very small partition for /boot (~ 256 mb < 512 mb) then the root partition “/” can be installed on software RAID array. However if you create a boot partition on one of the RAID disks then this disk will have less space then the other disks. On RAID it is preffered to have the same disk size. The new memory SD card can have a large capacity it is not sensitive to light or mechanical damage if you drop it and can be used to store data for a long time.


What is CF card?

CF is Compact Flash storage used for digital camera. It is less and less used today but is an interesting storage that is sometimes used as boot drive. You can use an IDE or SATA adapter to connect your computer internally to a small flash card and you can install the operating system on this card.

What is a PC card reader?

To read and write card you can you can install a 3.5″ card reader instead of a floppy disk. This is the new standard for a modern PC movable media and the floppy disk or any mechanical device. The new SD card can have a large capacity it is not sensitive to light or mechanical damage if you drop it and can be used to store data for a long time.

What is AIC ?

AIC = Add-in Card.

This is a new kind of storage that is Non Volatile Memory Express (NVMe). It is based on MLC (Multi Level Cell) like SSD except that is much faster then a normal SSD. In next picture you can see the brand: Intel 750 Series AIC Internal Solid State Drive (SSD)

This memory card is very fast and you can install the operating system on it or you can use this as an accelerator card for a very fast database. It can have 400GB or 800GB or even 1.2 TB and have price between $350 and $850 depending on the model. When you buy one of this make sure your motherboear suports it. You need at least a PCI express x4 free slot. If you have PCI express x8 OR PCI express x16 this will also work.