How to Choose a Hard Drive?
By Dr. Michael and Lee Penrod. (Contributions made by Alex Austin & Benjamin Wieberg)
Edited and updated by David Boss
Updated on April 3, 2013
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The following advice is based on many years of experience. It is provided as a free service to our customers and visitors. However, Directron.com is not responsible for any damage as a result of following any of this advice. You are welcome to distribute these tips free to your friends and associates as long as it's not for commercial purposes.
- There’s a new kid on the block. Solid State Drives, or SSDs, are the latest and greatest in storage technology. SSDs are similar to USB thumb drives or digital camera storage, only with higher capacity and speed. They use NAND-based flash memory, which is more expensive than a traditional hard disk drive, but has significant speed increases in both the read and write sequences. We’re talking Windows boot up speeds of seconds here, so the difference is quite noticeable. How is this done? Firstly, SSDs don’t have moving or mechanical parts. By utilizing flash memory SSDs are able to read (and sometimes write) upwards of half a gigabyte a second, all without having to spin up a disk (complete silence). The other factor that increases speed is an incorporated controller which bridges the NAND memory and computer. This small processor performs several speed saving functions that make reading and writing at high speeds possible. A major drawback to this technology is cost. As a rule of thumb, for SSDs you’ll generally spend about a dollar per gigabyte of storage. This is significantly less capacity than what a traditional hard drive can offer at the same price point. Another downside could be a slight but progressive degradation of performance due to limited amounts of information able to be written to the memory in a given lifetime. However, all of these shortcomings are really just arbitrary if what you’re looking for is speed. SSDs are the fastest you’re going to get, and might make the most noticeable difference in speed on your computer than any other single part. And we know, that’s saying a lot.
- For mechanical hard drives, SATA is the current standard. IDE drives are all but obsolete, with SATA holding more than 90% of the market share. Motherboards have built-in SATA controllers which allow the hard disks to reach their maximum performance on the 6Gb/s platform. While these drives are physically limited to much less than this maximum speed, there are still quite a few advantages in terms of capacity.
- Serial ATA interface is the way to go. The transition from IDE to SATA drives is almost complete. SATA holds more than 90% of market share. Today all modern power supplies come with SATA power connectors to support the establishing format. Just as well, all modern motherboards now have built-in SATA controllers and some include SATA cables. IDE ports have all but disappeared from small factor motherboards, and soon they won’t be included for compatibility due to their age. IDE would have found its demise sooner, but cheap optical drives were manufactured with IDE interfaces to keep costs down, prolonging the dependence on this format.
- SATA technology is cheaper than IDE, uses narrower cables, and easier to connect. These features make the choice clear. Four or years ago the choice was not so obvious. The following paragraph is what we used to say:
“Normal hard drives like we are all used to using are Parallel ATA (PATA). There is a new standard called Serial ATA which boosts transfer speeds up to 150MBs [and up to 300MB/s bursts with SATA2 technology) as opposed to a max of 133MBs with parallel interface. The SATA standard also improves airflow in the case because wide ribbons are no longer needed and a somewhat thin compact cable is used instead. Additionally, SATA2 offers a few features like Native Command Queuing, eSATA and other amenities. However - using SATA means you will need a SATA controller, a SATA drive, and a SATA power cable/adapter (often not included on power supplies yet). The actual speed improvement of SATA vs PATA is not much noticeable with current drives unless you are talking about the high end SATA drives using RPMs higher than 7200 which can burst through a wider channel than PATA. If you are building an average/upper end system there is currently no pressing reason to go SATA unless you are building for the future. PATA standard is slowly dying out, and high-end motherboards have even stopped including PATA interface support for their drives (they still include one, though, for CD-ROM/DVD-ROM drives that are still in their majority use PATA interface). For more information please see: PATA vs SATA.”
Today is the day when SATA is no longer seen as the future technology – the future has arrived, and SATA is dominating.
- There is only a small price difference among 320, 500 and even 750 GB hard drives. We suggest getting as large a hard drive as possible if you don't care to spend $10 or $20 more for 50 to 250GB more space!
- If you are working with a limited budget then a 250GB or 320GB drive is plenty for many people. However, people buy 500GB HDD more often because this size offers the best price-per-gigabyte today. Even doubling that capacity to 1TB is usually only 30-40 dollars more, and that’s a lot of storage space.
- How to calculate what is the best deal price-wise? Let us show you an example. Say, you have one hard drive 320GB for $42.99 and a second 500GB hard drive for $51.99. You want to know which one is the best deal. Thus, we have to find the price-per-gigabyte in each unit. The one that has the lesser price-per-gigabyte would ultimately be the best deal. So, $42.99/320GB = $0.134 or 13 cents per gigabyte. Then, $51.99/500GB = $0.103 or 10 cents per gigabyte. Thus, gigabyte-wise it is evident that 500GB is a cheaper solution than 320GB. However, it would be unwise to base decisions solely on the price; there are many other factors and features that should be considered when choosing storage like reliability, performance, noise level, warranty period, and so on.
- The usual speed of rotation in today's hard drives is 7200 RPM (rotations per minute). The previous generation offered speeds of 5400 RPM, which is rare for desktop drives but is common for notebook/laptop hard drives. Hard drives at the 7200RPM speed are a great choice; a faster spinning hard drive can retrieve data faster enhancing the overall user experience by eliminating delays. Raptors (a special model of Western Digital) are a 10,000 RPM hard drive and are extremely fast, though they are a bit pricey for a regular customer. They used to be geared towards enthusiasts and gamers, but SSDs are taking their place now. There are faster server grade hard drives that spin in the excess of 15,000RPM, creating lots of excess noise and heat while providing high levels of performance.
- In general, hard drives tend to be noisy. However, each manufacturer has their own technology to reduce the mechanical sounds. Some brands are quieter than others. Many simply lower the performance, while others change the design. When choosing a hard drive look for special notes attributed to reduced noise. Some will even clearly state their decibel level right on the box. However, if you’re looking for completely silent, SSDs would be your best bet.
- Many new hard drives offer a bigger cache than ever before. Older hard drives were offering 2MB-4MB of internal buffer, while the newest generation offers anywhere from 16MB-64MB. This "buffer" memory is a cache for recently read information, meaning that if the file is read sequentially then the hard drive can simply send out data from the buffer rather than re-reading it from the disk again.
- Hard drives come in different sizes fitted for the allowable space in certain applications. The desktop size today is 3.5" and it fits all computers. Notebooks accept 2.5" hard drives. 5.25" was the regular size years ago (the size of DVD-ROM drives), if you have a 5.25" bay and 3.5" hard drive then you can use special rails "spacers" to fit neatly.
- With high capacity technologies, hard drives are able to use fewer platters (spinning disks inside) to hold the same amount storage, thus requiring fewer heads. Less heads means a lower risk of a crash or other hardware failure.
- About the warranty. The manufacturers have different warranty periods and most will only honor warranties if purchased from an authorized distributor or a registered reseller. We, Directron.com, are an authorized reseller for all hard drive brands that we sell. By the way, Seagate brand offers unheard of 5 year warranty on most of their hard drives. Of course, a warranty can do only so much when important data is lost. That is why the best warranty is to back up your data! We cannot stress this enough, your data is in your hands. If you have crucial information on your drive, please back it up. This can be done with another internal or external hard drive. Back up your data often, as it’s hard to “plan” for problems.
- RAID can be used to increase drive performance (RAID 0), improve data integrity (RAID 1), or include both (RAID 10). For RAID you need 2 or more similar drives and a RAID Controller, which can either be in the form of a card, integrated motherboard feature, or software (server operating systems). Those looking for extra performance and those doing large applications such as database/server work are encouraged to look into these Redundant Arrays of Independent Disks. RAID controllers exist for SATA, EIDE, SAS, and SCSI.
- The very first use of RAID was to safeguard data. RAID 1 is known as mirroring method where 2 hard drives have the exactly the same information. If one dies then the other has a complete copy of data.
- Most common among regular users is RAID 0, for added performance. You would need 2 drives of the same size (hopefully of the same brand and model) and capability to run RAID 0 on your hardware setup. "RAID 0" writes half of data on one drive and another half on the other drive, almost doubling the speed of operation. Thus, RAID 0 offers a 70%-80% increase in performance. The huge problem with RAID 0 setup is that neither drive has even partially complete data. Loss of all data occurs even if one single drive fails. Data on the second hard drive becomes unusable without the complementing data on the failed hard drive. Thus, RAID 0 can be twice as fast but is also be twice as risky.
- The solution to RAID 0 lack of redundancy problem is to feature a third hard drive that will record byte differences and data can be easily reconstructed with a single drive failure. The described scheme is RAID 10 (aka RAID 1+0 or 0 +1). It requires 4 similar hard drives where two drives are striped together and the other two drives mirror the striped array. This allows for you to swap hard drives if one should fail at any point. This adds a redundancy aspect to a raid 0 setup preventing data loss.
- Nevertheless, RAID is not a substitute for back-up. The best back-up drives are external and can be plugged in during back-up and kept away from the system any other time. This is done in case of fire, electric, or water damage. In rare cases a system suffers from a power failure that destroys all connected components, even external ones. Therefore, if a back-up drive is kept in your personal computer or server, then it is likely that it will have been destroyed as well. Moreover, it is best to have 3 methods of back up for a server: RAID 1 or 10 in the actual server, a separate external backup drive on the network, and a weekly backup stored miles away. While the initial cost of the hardware can be pricey, when a disaster strikes you won’t have to worry about your data. In addition, having the proper setup but not actively doing backups renders this hardware useless.
- Then, if you are REALLY serious about getting fast access to your data, such as large databases and image files, consider using one of the latest hard drive technologies, Serial Attached SCSI (often referred to as "SAS"), which have a typical access time of 3.5- 4.0ms! Wow! That's FAST! But you'll pay for the speed. You also need to use a more expensive SAS controller. Speed of the hard drive may also become a problem if the hard drive is located in the box next to you. These drives spin at very high speeds and are not shy in generating noise.
- Let us warn you not to buy refurbished hard drives, no matter how low the price is. The potential for trouble down the road is not worth the savings. That's why Directron.com is staying away from refurbished hard drives as much as possible. Used but working hard drives are a better, and possibly more reliable, way to save money. If we do sell a refurbished hard drive then it is clearly marked as such on the product page.
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