The comparison for cost and speed is relatively simple to find and generally well agreed upon. However, there is very little information about the "failure behaviour" — how much advance notice you will have when either type of device begins to fail, and what recovery options may be available after the fact. How you choose to utilise each based on their respective failures is likely to greatly impact your experience with both.
There is a broad consensus regarding the speed and cost comparison. There is also a more important question to consider. A hard drive normally will give you several weeks’ worth of warnings before failing. On the other hand, an SSD often has no warning at all — and as such, this significantly alters the protection you have.
This is the single most important factor when comparing the two.
A hard drive will usually give you advance notice. If a file takes longer than normal to open up, if your computer locks up for about thirty seconds before continuing and the count of reallocated and pending sectors keeps increasing, then that could be your signal. However, you may have several days, even weeks to move all data off to back-up. At that time the drive is still accessible — therefore you can transfer data off using your own methods with no cost.
A solid state drive doesn't normally. SMART accurately reports flash wear but hardly anything about controller health, and it's the controller that fails spectacularly. An SSD that shows 96% life remaining on Monday could be totally undetectable on Tuesday, with nothing in-between.
The logical strategies therefore differ. On a hard drive, monitoring "earns its keep" because warning is actionable. On an SSD, only backup(s) that exist protect you — there is no deterioration phase for monitoring to detect.
And this always catches people off guard!
Nothing occurs to deleted data until some new file writes over it. On a drive with free space, files routinely recover weeks after they were deleted. If you cease writing data, time generally works in your favour.
A TRIM command tells the controller to remove data from those blocks, and that removal will occur in the background as long as the device is on. That removal can never be recovered.
Mechanical failures are repaired using donor heads, repairing boards or transferring platters. These repairs require invasive operations; they're also well-understood and frequently successful.
Vendor mode gives direct access to the translation table for your controller. This is usually successful, but when the controller cannot be revived at all, options become much fewer.
They have different jobs.
SSDs win for anything you use daily. The absence of mechanical components eliminates the possibility of a "head crash" or a stuck bearing, but also results in much greater shock resistance, which is why a laptop with an SSD survives knocks that would finish a spinning disk. The increased speed contributes to a fundamentally different user experience.
Hard drives win for capacity and for archives. At larger capacities, cost per terabyte is still dramatically less expensive than solid-state flash. Unpowered hard drives are able to retain their data for many years. Flash memory is not; it stores electric charge behind an insulating material and that charge leaks out over time when there has been no power supplied to the drive. This can happen faster in older, worn-out or warmer-stored cells.
This gives rise to the practical guideline that most users follow incorrectly: the SSD should be installed in the computer, while the HDD should be used for archiving. When using a USB stick or keeping an SSD in a drawer as a backup of some files for an extended period of time, you are asking the technology to do what it was not designed to do.
Check the reallocated and pending sector counts from time-to-time. These provide actual warnings about your hard drive. If you have any pending sectors reported by a hard drive that is important to you, then you need to take action.
The problem with your SSD is there is nothing reliable to watch for before it fails. So don't rely on watching anything. Be prepared to lose data at some point.
Both technologies will cause you to lose data if they fail. There are different types of failures but neither type is rare enough to make having only one copy of your important files safe.
If you're going to store a spinning disk long-term, it benefits from being powered on now and then. A solid-state disk that is stored and never powered on for years is the arrangement most likely to disappoint you.
In daily use, generally yes — solid-state storage has no moving parts so cannot seize or experience a head crash; also they are less likely to suffer from the impact of physical movement and drops. On the other hand, once an SSD does fail, it often occurs without warning.
Hard drives. By far. Sector count increases and file retrieval times increase over days/weeks as long as the hard drive is readable. An SSD can have 96% life remaining and not be detected the next day.
Yes, very much so. It is common for deleted data to remain on a hard disk until the disk writes new information to the area where it was located. This often takes weeks. The TRIM command deletes the blocks containing data within minutes of data being deleted from an SSD and no tool can retrieve the previous data.
A hard drive. Flash memory retains data through stored charges behind an electrical insulator which then drain due to leakage over time when the device is never powered. If you leave an SSD in a drawer for years, that is the arrangement most likely to disappoint you.
SSDs for speed; and for survivability in laptops. Keep a hard disk for the archive and the backup, because at capacity the price per TB is significantly less expensive. Also, unpowered retention is much longer on hard disks.
We charge the same price as single drives regardless whether the unit is a single SSD or a traditional single drive: both are from £300 plus VAT. The difference lies in the probability of recovery. When TRIMmed deletions occur and/or encryption happens to the flash memory it essentially closes the case for certain types of SSD failures. We determine this through the free diagnostics offered by us.