2020. Time to clean out old disks. I started with some Samsung Spinpoint HD204UI disks.
The Samsung Spinpoint HD204UI 2TB 5400 rpm 3.5 inch disk was released in 2011 and would last about 10 years with steady use in a stable air conditioned environment. My disks have hardly any use, just the occasional backup, but I am replacing them with 2.5 inch USB 3 disks to save power and space.
The disk has a capacity of 2 TeraBytes from the days when that was a big disk. Today the 2 TB size is at the low end of 3.5 inch disks, in the middle of 2.5 inch disks, and still at the higher premium end of SSDs.
For portable storage, I spend the extra money on an SSD. I currently use 1 TB SSDs because they are in the middle of the SSD size range and are cheap. When 2 TB SSDs are no longer premium devices, I will upgrade my portable storage.
I need more storage due to using a higher resolution camera and to taking more video. My desktop computer contains several 3.5 inch disks and each year the largest one is doubled in size. 4 TB was the cheapest size (per TB) at the start of 2019 and 6 TB is the cheapest size at the start of 2020. There is no reason to use an old 2 TB 3.5 inch disk in 2020.
External USB disks are limited by the USB 3 power. For anything over 1 TB, you have to use a slow 5900 rpm disk. Some of the new 2.5 inch 5900 rpm disks are as fast as old 3.5 inch disks due to the larger capacity disk surfaces requiring fewer rotations to access the same data.
How do SSDs compare?
All prices are Australian dollars from shops in Sydney or with delivery to Sydney.
For around AU$450, you can get a reliable 2 TB M.2 format SSD. A good cool solid USB 3.0 case is $30 and a USB 3.1 gen 2 case is $50. I would buy that type of setup for the active use of an external disk. Drop proof. Small enough to carry anywhere. A simple plastic bag to protect it from any liquids or rain when not in use.
The SSD has enough speed to be used actively for file browsing and searches. The USB 3.0 interface can be slow for frequent small random updates, something like a database. The US 3.1 gen 2 interface removes the speed limit. This setup is all overkill for a backup disk.
The old disk has a 32 MB cache to add some speed to small bursts of activity. Photographic images from a full resolution camera are that size and would flood the cache making the cache useless. Modern disks appear to have a minimum of 64 MB cache, which would let the disk buffer one file while reading the next file. Some disks have up to a GB of cache, a size that would handle small video files. Cache size is almost meaningless for backup disks.
Magnetic disks are limited by their rotation speed. The old disk rotates at 5400 rpm (revolutions per minute). The fastest expensive disks run at 10,000 rpm but you can get faster SSDs for the same price. The fast affordable fast magnetic disks run at 7200 rpm, giving you about a 50% improvement on read and write speeds. Most of the 2.5 inch alternatives are limited to 5900 rpm by the low amount of power available through USB 3.
I found just two 2.5"disks running at 7200 rpm and both are limited to 1 TB. I currently need only 1 TB of backup for an "rsync" style backup, described below, and ordered one of the 7200 rpm disks for my daily backup. The faster rpm will make up for some of the slower aspects of 2.5" disks. For the less frequent "Timeshift" style backups, I will stick with the 2 TB size and accept the lower speed.
The new small disks, 2.5 inch, gain some speed from packing data closer together, reducing the seek time when the read/write heads have to move to a new track. Offsetting this is their low power usage which limits the power the device can use to move the disk heads. When you have to limit a disk to battery power or to USB power, you cannot accelerate disk heads at full speed. That low power operation slows down your work, a good reason to use SSD.
The old disk uses 12 volts at 0.5 amps and 5 volts at 0.85 amps, for a total of 10.5 watts. This is too much power for a USB connection. You need a mains powered enclosure. They typically use a power block that consumes more power. You might have 20 watts going into the power block.
2.5 inch disks use only 5 volts, the same as USB, and use less than 2 watts, an easy amount for USB 3. The only time your disks will be limited is when you add multiple external devices to the one USB hub. An unpowered USB hub can run only one disk with nothing else. A powered hub might run two disks or more, depending on the power supply. I have a powered hub that can run two disks plus a bunch of low powered devices like keyboards.
The Samsung HD204UI is noisy compared to the same generation Seagate 2 TB 7200 rpm disk and to a Western Digital Green 2 TB 5900 rpm disk. The main noise is the head rattling around on long seeks. I do not use these disks in a desktop computer, reducing the impact of the noise. I used the disk for an occasional backup and I usually walked off to do something else while the backup ran.
For 2.5 inch disks, I found complaints about rattling noises for only WD disks and only some models. Noise indicates a bad mechanical design that will produce problems. Those complaints about disk noise match up to complaints about WD disk failures in 2.5 inch disks. The noise from 3.5 inch disks does not match up against the reliability of various models.
Every brand has the occasional dead on arrival complaint. Disk can be damaged by bad handling between the production line tests and the final installation. The real problems are the disks that die after a week or a few months of use. You do not want a backup disk to die. You should not have to pay a premium to get a special model designed for reliability.
WD disks had too many complaints back before they purchased HGST, which was a merger of the best Hitachi and IBM disk storage technology. Some of the HGST technology was shared with Toshiba, a supplier of bland but reliable USB disks.
The good brands of SSDs now have a better track record than magnetic disks. SSDs do not die when knocked off your desk while in use. If you work in a busy environment where other people touch you computer, use SSDs. The very few times a good brand of magnetic disk failed for me were all associated with someone else touching them, moving them, making room for something else on my desk, or opening the case to move cables.
The disks produce almost no noise from reading, writing, and sequential track to track seeks, making the disks suitable for backup type storage where they are switched on only for a short while each day. The disks made too much noise when used for random access, the type of access you get when used as a regular system or data disk.
The disks were five years old when I first started down grading them to backups. Mine date from June 2011. With continuous use, they would be close to end of life in 2019. For weekly backups, their most common use, the disks could last for a few more years.
In practice, the bearing dry out in Australia's hot weather. My seaside location increases rust and corrosion. To get the maximum life from the disks, I would have to run them in expensive air-conditioning. It is cheaper to replace them and get the benefit of the replacements storing more data while using less electricity.
The average access time varied from 16.53 milliseconds to 16.81 across several tests. This is a common access speed on lower priced medium size 3.5" disks. For two to four times the price, you can get down to 12 milliseconds. SSD is a better option and I now have all my frequently used data on SSD.
Access time has little effect on backup and the handling of large files. Access time has a big effect on databases. If I were using these disks for a database, I would replace the disks every three to five years to get better speed from the new technologies.
The average read speed was constant at close to 111 megabytes per second across many tests. The only time there was anything faster was during very small tests where most of the reads are from the cache. The cache, at 32 megabytes, is too small to make a difference during regular use.
For something like a Web site, where most accesses are reads, I would have used two disks in a RAID 1 configuration to make reads twice as fast. If these disks were used like that from day one, I would be replacing them now due to wear.
The average write speed varied from 71 MegaBytes per second for small files up to 138 MB/s for large files. The 138 MB/s is the continuous sequential write speed you can expect when writing long video files. The 71 MB/s is the random write speed you can expect when writing short files. You can expect a slower write speed for database updates where you are rewriting random sectors.
Combining two disks in RAID 1 does nothing to improve write speed. Combining several disks in a RAID 5 configuration does give you a faster write speed. When you have to replace a disk in a RAID 5 array, you want all your disks at a similar speed because the array will perform at the speed of the slowest disk. The HD204UI is too old to rely on as a replacement.
When you have to replace one disk in the array, you should look at replacing the whole array as all of the original disks will wear at the same speed.
Modern disks are faster. For a large backup, a faster disk is better. You might cut your backup time in half using a modern 7200 rpm disk.
After the initial full disk backup, you might perform incremental backups using something like rsync. The HD204UI and similar 5400 rpm disks are fast enough for the incremental backup. I have used the disks for a big weekly backup overnight, requiring several hours, followed by daily incremental backups taking less than an hour.
Modern 7200 rpm disks and most SSDs are faster for random writes. I have only one old SSD that is slower than the HD204UI for all writes, due to the slow erase cycle of the SSD. Magnetic disks still perform well, against SSDs, for backups in the background.
Some modern SSDs have faster read speeds and similar continuous write speeds. Only the expensive SSDs have faster large volume writes. When you need a disk for a small database, a small expensive SSD is the best choice. For large files, like video files, a large magnetic disk is often the best choice. The important thing is to compare real speed measurements for small random writes and sequential writes, not the advertised write speed.
Electric power costs money. Removing the heat produced by the power is another expense. You can get 2.5 inch disks with similar performance characteristics and a lower power usage. For small capacities, the difference in price is not significant due to high performance 2.5 inch disk using less material to manufacture. When I replace a HD204UI for backup, I buy a 2.5 inch equivalent.
Disks prepacked in USB 3 enclosures
The Toshiba Canvio Basics USB 3 hard drives are currently the best purchases at our local shops for capacities up to 4 TB. 2020 should bring some new disks using USB 3.1 gen 2 enclosures to get slightly better throughput and to make better use of any on disk cache.
The HD204UI disk is too noisy for regular use in a desktop computer. For a backup, you can get a similar capacity and speed in a modern 2.5 inch disk while using significantly less power. For any magnetic disk over five years old, you should plan their replacement. Either shop around for a quiet 7200 rpm disk for extra capacity and a higher speed or buy a 2.5 inch disk to save on electricity.