External Drives

In this weblog post several different types of external drives will be examined for different purposes.

Hard Drives

The main purpose for having external drives is to have off-site backup of files stored on a family Network Attached Storage server(NAS). It is to ensure that irreplaceable data is not lost by storing it in two separate locations. There are five drives with historic data that are permanently kept at a second location. This is because all that data is already on the NAS. Then there are six drives that are divided into two sets of three disks each. One set is taken regularly to the second location. Once there, the other set is returned home, and used to update files on a regular basis for the next couple of weeks. In a worst case situation, a catastrophic event would result in the loss of up to two weeks data.

Currently, hard drives offer lower price than solid-state drives when mass storage is needed, particularly in the range of 1 – 5 TB. Western Digital My Passport products are inexpensive, but offer good performance. This is due to using the USB 3.0 protocol, with its cable terminating in a Type-A connector. In addition it comes with an excellent disk controller. There is 256-bit AES Hardware Encryption available. The maximum transfer read speed is 174 MB/s , and the maximum write speed is 168 MB/s. In general it offers acceptable performance and reliability.

If one selects the Western Digital My Passport Ultra, there are two main differences. First, it uses a more robust metal enclosure. Second, the USB 3.1 protocol is used, with its cable terminates with a USB-C connector, but includes a Type-A adapter.

There are different manufacturers of HDD units including Samsung, Seagate and Toshiba. I have mainly kept to Western Digital, because none of my eleven My Passport drives have failed. In contrast, one of my two Seagate Backup Plus drives failed after minimal use. The second, remaining Seagate drive was quickly given away. Others are not so enthusiastic for My Passport drives. Slant ranks two versions of Seagate Backup Plus as the best drives. I have also considered purchasing Toshiba Canvio drives because of their compact physical size, but their smaller 3TB capacity makes them less practical for a person with large quantities of data to store.

Solid-State Drives

Solid-state drives (SSD) become expensive with large capacity disks. The Western Digital My Passport SSD is considerably more expensive, with storage capacity ranging from 256 GB – 2 TB. There is a USB 3.1 Type-C port and AES 256-bit hardware encryption. At the moment, the main disadvantage of these drives is price, which is more than four times the HDD equivalent.

Transfer speed is up to 540 MB/s. This speed increase is because SSDs access data electronically instead of electro-mechanically. This also improves their mechanical ruggedness. There is continued debate about the reliability of SSDs, with some finding them more, others less, reliable than HDDs. SSDs are sensitive to sudden power interruption, which can result in the loss of a drive.

While there are wireless drives, not all devices are equipped with Wi-Fi. Almost without exception, these devices are equipped with USB ports. Thus, there is no need to invest in wireless external drives.

Price for assorted 2 TB My Passport models (2020-02-08) in USD before taxes and shipping charges.

HDDUltra HDDWireless HDDSSDWireless SSD

USB flash drives aka memory sticks aka thumb drives

Flash drives are used for various purposes. Perhaps the most common use is for the transport of files when a person will not accompanied by their own laptop or other machine where the files are normally used. They are especially useful if one has to upgrade a number of machines to several different devices.

For these purposes one wants a fairly rugged and durable piece of equipment. Personally, I use a Kingston DataTraveler Elite G2 64GB flash drive. For the security minded, the main drawback of this drive is that it is not encrypted. If necessary, one could password protect sensitive individual files. One reason for selecting this drive is its metal casing, which is shock- and water-resistant. It reads at a maximum of 180 MB/s, and writes up to 70 MB/s.

The more security minded may want to consider a SanDisk Extreme Pro USB 3.1 available in 128 and 256 GB varieties. Its read and write speeds are extreme, up to 420MB/s and 380MB/s, respectively. It has an aluminum casing and comes with 128-bit AES encryption software. Its price is also extreme.

One of the main uses of flash drives here, is the storage of assorted Linux operating system distros. Each distro is placed on a new Kingston DataTraveler G4 16 GB flash drive. At one time, these were upgraded as new distro versions became available. However, after a couple of drive failures one learned that this was false economy. 16 GB drives are used not because one needs so much space, but because they are cheaper than 8 GB drives!

There are many times one needs to give people files on a flash drive. This has to be regarded as one of the normal costs of having relationships with people, in much the same way that serving visitors (invited or not) a cup of coffee is an investment in smooth social relationships. These G4 drives are the standard drives given to people. They are usually bought online, ten at a time.

SD Cards

While this section is labeled SD cards, some would argue that microSD cards would be a more appropriate heading. The original SD format is far too large for handheld devices. If a port on a device only takes original or mini-sized cards, passive adapters are available.


A 10 MB HDD for USD 3 500 in 1980, was not an excessive price. The 1 MB of RAM on the Digital Equipment Corporation (DEC) VAX-11/750 mini computers I used cost over NOK 1 000 000 each in 1980. That is about USD 200 000 in 1980, or about USD 620 000 today (2019). The HDD pictured would cost over USD 10 000 today (2019) taking the value of money into account, which would make the cost of 1TB of storage equal to USD 1 000 000 000 today (2019). Yup, that’s one billion dollars!

SSD = Solid State Drive; HDD = Hard Disk Drive.

The Summary:

For daily operations on a desktop or laptop computer, SSDs are better (read: faster, quieter, more energy efficient, potentially more reliable) than HDDs. However, HDDs cost considerably (6.5 times) less than SSDs. Thus, HDDs are still viable for backup storage, and should be able to last at least five years. At the end of that time, it may be appropriate to go over to SSDs, if prices continue to fall.

The Details:

This weblog post is being written as I contemplate buying two more external hard disk drives (HDDs), one white and one blue. These will be yet more supplementary backup disks to duplicate storage on our Network Attached Storage (NAS) server, Mothership, which features 4 x 10 GB Toshiba N300 internal 3.5″ hard drives rotating at 7200 RPM. These were purchased 2018-12-27. While the NAS has its own backup allowing up to two HDDs to fail simultaneously, a fire or other catastrophe would void this backup. Thus, external HDDs are used to store data at a secret, yet secure location away from our residence.

The last time external hard disks were purchased was 2018-09-04. These were Western Digital (WD) My Passport 4TB units, 2.5″ form factor, rotating at 5 400 RPM, with a USB 3.0 contact. One was red (costing NOK 1 228) and the other was yellow (at NOK 1 205). However, we have nine other 2 – 4TB units, some dating from 2012-11-15. Before this we had at least 4 units with storage of 230 GB – 1 TB, dating to 2007-09-01. (We are missing emails before 2006, so this is uncertain territory, although if this information were required, we have paper copies of receipts that date back to 1980).

The price of new WD My Passport HDD 4TB units has fallen to NOK 1 143. New WD My Passport Solid State Drive (SSD) units cost NOK 2 152 for 1TB, or NOK 3 711 for 2TB. That is a TB price of about NOK 1 855, in contrast to about NOK 286 for a HDD. This makes SSDs about 6.5 times more expensive than HDDs.

I am expecting to replace the disks in the NAS, as well as on the external drives, about once every five years. Depending on how fast the price of SSDs sink in relation to HDDs, these proposed external HDDs could be the last ones purchased.

As the price differential narrows, other disk characteristics become more important. Read/write speed is especially important for operational (as distinct to backup) drives. Typically, a 7200 RPM HDD delivers an effective read/write speed of 80-160MB/s, while an SSD will deliver from 200 MB/s to 550 MB/s. Here the SSD is the clear winner, by a factor of about three.

Both SSD drives and HDD’s have their advantages and disadvantages when it comes to life span.

While SSDs have no moving parts, they don’t necessarily last longer. Most SSD manufacturers use non-volatile NAND flash memory in the construction of their SSDs. These are cheaper than comparable DRAM units, and retain data even in the absence of electrical power. However, NAND cells degrade with every write (referred to as program, in technical circles). An SSD exposed to fewer writes will last longer than an SSD with more. If a specific block is written to and erased repeatedly, that block would wear out before other blocks used less extensively, prematurely ending the SSD’s life. For this reason, SSD controllers use wear levelling to distribute writes as evenly as possible. This fact was brought home yesterday, with an attempt to install Linux Mint from a memory stick on a new laptop. It turned out that the some areas of the memory stick were worn out, and the devise could not be read as a boot drive. Almost our entire collection of memory sticks will be reformatted, and then recycled, a polite term for trashed!

Flash memory was invented in 1980, and was commercialized by Toshiba in 1987. SanDisk (then SunDisk) patented a flash-memory based SSD in 1989, and started shipping products in 1991. SSDs come in several different varieties, with Triple Level Cells (TLC) = 3 bit cells offering 8 states, and between 500 and 2 000 program/ erase (PE) cycles, currently, the most common variety. Quad Level Cells (QLC) = 4 bit cells offering 16 states, with between 300 and 1 000 PE cycles, are starting to come onto the market. However, there are also Single Level Cells (SLC) = 1 bit cells offering 2 states, with up to 100 000 PE cycles and Multi-Level Cells (MLC) = two level cells with 2 bits, offering 4 states, and up to 3 000 PE cycles. More bits/cell results in reduced speed and durability, but larger storage capacity.

QLC vs TLC Comparisons:

Samsung 860 EVO SSDs use TLCs while Samsung 860 QVO SSDs use QLCs. The 1TB price is NOK 1 645 (EVO) vs 1 253 (QVO), almost a 25% price discount. The EVO offers a 5-year or 600 TBs written (TBW) limited warranty, vs the QVO’s offers 3-years or 360 TBW.

With real-world durability of the QVO at only 60% of the EVO, the EVO offers greater value for money.

It should also be pointed out that both the EVO and QVO have a 42GB cache that allow for exceptionally fast writes up to that limit, but slow down considerably once that limit has been reached.

In contrast to SSDs, HDDs rely on moving parts for the drive to function. Moving parts include one or more platters, a spindle, an read/ write head, an actuator arm, an actuator axis and an actuator. Because of this, an SSD is probably more reliable than an HDD. Yet, HDD data recovery is better, if it is ever needed. Several different data recovery technologies are available.

The Conclusion:

The upcoming purchases of two My Passport 4TB external HDDs may be my last, before going over to SSDs for backup purposes, both on internal as well as external drives. Much will depend on the relative cost of 10TB SSDs vs HDDs in 2023, when it will be time to replace the Toshiba N300 10TB HDDs.

For further information on EVOs and QVOs see Explaining Computers: QLC vs TLC SSDs; Samsung QVO and EVO.