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Disks

Disks, hard, magnetic, optical, and electronic, store our valuable data including family photographs you can not repeat if the original is lost. Here is the who, what, when, where, and why of disks.

What

Magnetic disks

Magnetic disks are the oldest form of disks. Magnetic recording of sound on wires was used before World War II. The Germans invented superior Magnetic disks are the oldest form of disks. Magnetic recording of sound on wires was used before World War II. The Germans invented superior magnetic tape before WW II. After the war, computer companies started recording on drums then on disks similar to records. IBM invented the Winchester technology that made disks reliable at high speeds.

Optical disks

Optical disks, including rewritable CDs and DVDs. are practical for long term storage of medium amounts of data but are slow to write and they fail if you frequently rewrite over the disks. They are good choices for logs where you write once, keep the log for many months, then reuse them. Optical disks are not a replacement for magnetic disks.

Solid state disks

Solid state disks, SSD, are faster than optical disks and, on average, are similar to magnetic disks. The read speeds of most SSDs are many times better than the read speed of magnetic disks. Writes to SSDs are slower than reads and are often slower than writes to magnetic disks. When you use a common mixture of reads and writes, you only get a speed advantage from SSD when using the newer more expensive SSDs.

My desktop workstation is faster because I use an SSD. I had to carefully research the different brands and models then pay above average price to get a real speed improvement.

SSD speed is also influenced by size. Within a model range, the larger disks are often faster because they can access the extra space in parallel. If you are looking at a range including 32 GB, 64 GB, and 128 GB, the 64 GB version might be twice as fast as the 32 GB version because the SSD controller chip can access the 64 GB as two sets of 32 GB in parallel. The 128 GB version might be faster than the 64 GB version but not twice as fast because the controller chip is not fast enough to handle four lots of data in parallel.

Memory and RAM disks

You can allocate parts of your computer memory, commonly called RAM, as a disk to store temporary data. You can buy add-on cards to emulate disks in their own memory. Both types fail when the electricity fails. You cannot use them for long term storage.

To use a RAM disk, check your current memory allocation. If you have lots of spare memory, use a RAM drive. One of my computers has 8 GB of memory and rarely uses more than 2 GB. I could easily allocate 4 GB to a RAM disk then place all temporary files there. I tested that option on one computer and it cut 20 seconds off the computer start up time, a similar amount to SSD. The test machine had 8 GB of memory and used Windows XP, which uses only 4 GB. The RAM disk software grabbed the unused 4 GB for the temporary files.

4 GB is a bit small for most of my projects and SSD speeds up all file accesses, not just temporary files. SSD is the better choice in most cases. If you had a new Intel LGA1366 based computer with 6 memory slots and a 4 GB memory card in each slot, you would have 24 GB of memory and could allocate 10 GB or more to temporary files. You usage will vary. When you measure peak memory usage, allow for double that or more for the peaks you do not see. When you measure your temporary file usage, allocation between 4 and 10 times that amount for the occasional large peak. You soon realise that RAM disk is not magic until you have really large amounts of unused RAM.

Who

Magnetic disks

Hitachi purchased the disk manufacturing division of IBM and produce reliable magnetic disk drives. Their current range for home and office use is quiet and efficient. Usually Samsung are cheaper but recently some of our local shops had a limited range of Hitachi disks on sale at a lower price than the equivalent Samsung disks. The Hitachi disks are just as quiet and reliable as the Samsung disks.

Samsung is the current leader for low cost reliable quiet magnetic disk drives in Australia. Price comparisons vary from country to country. Based on regular retail prices in Sydney, Australia, including common discount prices but not rare end of model run out sale prices, everything dearer than Samsung has little practical advantage over the Samsung for home and office use. Everything cheaper than Samsung is rubbish I would not use. Occasionally the Samsung discounts dry up and other good brands dip lower in price.

Seagate were the leaders for years. They pioneered reliability and were the best choice until they started purchasing other companies. I had just thrown out a bunch of Maxtor disks because of reliability problems when Seagate purchased Maxtor in 2006. A short time later some batches of Seagate disks failed frequently. Seagate produced previous bad batched when moving to new production facilities in Asia. They lead everyone on speed, the first 7200 RPM drive, the first 10000 RPM drive, the first 15000 RPM drive, and sometimes rush new designs and factories into production.

Fujitsu used to be among the leaders then were sued big time in a class action alleging Fujitsu knowingly sold disks with high failure rates. I never purchased Fujitsu disks because Seagate always had something bigger or faster or quieter and always at a better price.

HP sell a small range of disks at ridiculously high prices. I do not know who makes them because HP do not have disk manufacturing facilities.

IBM sold their disk manufacturing facilities to Hitachi but still sell disks with the IBM brand on the outside. They are probably Hitachi disks.

Lenovo sell disks. Lenovo is a Chinese company that manufactured their own PCs and made some IBM PCs under contract. Lenovo then purchased IBM's PC division and now manufacture the ThinkPad notebooks originally designed and made famous by IBM. I do not know who makes Lenovo magnetic disks. Lenovo use Samsung solid state disks.

Western Digital have the largest range of magnetic disks but you will never use most of them because they are mostly older designs. Western Digital have large drives and quiet drives and a lot of people report great reliability from their WD drives. The problem is working out which models are reliable, which models are quiet, and so on. When I hear about good WD drives from people who test extensively, they almost always quite model numbers that are no longer available or are only available on special order at a high price.

Optical disks

Pioneer are one of the original optical disk developers. I recommend Pioneer based on their drives always working as advertised. There are other brands that are slightly cheaper. I tried most of the other brands and they all failed. Some failed immediately. Some failed within the year. Some failed one out of three drives. I have used hundreds of Pioneer drives across many projects and had only one failure in a very dusty environment. The one notable brand I have not tried is Samsung.

Solid state disks

Intel lead the way for big corporate SSDs. Kingston licence Intel technology to make a moderately priced range for your home and office workstations. There are lots of other brands. Some are expensive compared to their speed or size. Some have a huge range of models across a lot of price ranges. When you read a review of SSD, you cannot reliably compare the review to what is sold in the shops unless you get an exact match on the model number of revision number. The slightest change in either could mean a completely different internal arrangement of chips or a different brand of chip, and huge differences in performance.

The two critical factors are the controller chip and the memory chips. A slight change in controller chip might make a new version of an SSD twice as fast. You read the review. The shop then sells you the earlier version.

Memory chip selection is less critical. The memory chips are stable. New versions might be slightly faster. They change slower than the controller chips. SSD manufacturers do not use memory chips that are faster than the controllers. They tend to use slower chips then get speed by using several in parallel. That is why a larger drive in the same range might be a lot faster.

When

SSDs are the first choice for notebooks because notebooks have incredibly slow disks and those disks break when bumped. SSDs solve the speed and reliability problems.

Your desktop workstation probably has too many large files to use SSDs for everything. Video kills SSDs. Use an SSD for your system partition then use magnetic disks for your data. You could use a couple of magnetic disks in a RAID 1 array for speed. If you have the space and money for several magnetic disks, put them in a RAID 5 array to get a huge space with lots of speed.

Where

SSDs do not break when bumped. Use them for portable devices. Magnetic disks break when bumped while rotating. Use magnetic disks on devices that are stationary, your desktops and servers. Magnetic disks are portable when switched off, making them suitable for data you carry from desktop to desktop, say from home to the office.

The problem with those small magnetic disks in USB enclosures is the very high chance that someone will slam a package or heavy book down onto your desk on top of your portable disk while the disk is switched on and rotating. An inexpensive slow large SSD could be a safer option.

Why

Whatever you buy now will be obsolete by the time you finish signing the credit card slip. Capacity increases every few months. Speeds increase every few months. The problem is the amount of work required to upgrade every few months. You save your time by planning a year or more ahead.

You will add more applications and you will accumulate more files. You will need a faster computer a year from now. You may not need a faster processor for those extra files, just faster disks. Plan on making your disks twice as fast as you think you need. If you are looking at one disk, think about two in a RAID 1 array for extra speed or the use of an SSD. The step up from RAID 1 is RAID 5 with at least four disks. The step up from regular SSD is a more expensive SSD with a faster write time.

A yearly upgrade is a good plan because prices drop every year. Check online discounts for data storage as most sites have closeout deals when new versions come out.

When you do upgrade, a small extra investment in premium products may give you a big speed advantage. Magnetic disks are evolving to gain more capacity and use slightly less power. SSDs are improving rapidly in speed, capacity, and price. Upgrade your SSDs every year for the next few years. The old SSDs can be relegated to external USB cases for use as portable drives.

Further reading