For many, the SSD drive seems to be the perfect solution, as it offers many advantages, but over the last year many articles and reports have detailed how relying on SSD technology may be a risk. It is important to assess the correct usage for each type of drive, to ensure your data is not endangered.
Despite the many warnings about how data recovery from an SSD is a more complex process, with a lower rate of success, many users are not heeding them. Data recovery from a traditional hard disk drive is easier and success if more likely than from an SSD.
Pros and Cons of SSDs and Hard Drives
The increased speed of an SSD drive is its main advantage over a traditional hard disk drive. Another advantage is the lack of moving parts, which not only makes it less susceptible to damage from an impact, but also makes a negligible level of noise, as well as consuming less power. The claims of the better reliability of SSDs have come under scrutiny in the last year and now appear to be unsubstantiated.
The main advantage of a traditional hard disk drive is the price per gigabyte, which is much less than an SSD. Although there are some SSDs available with a much higher capacity than the current 10TB available for a traditional hard drive, they are prohibitively expensive.
Install an SSD or Hard Disk Drive
The common consensus, especially among the data recovery community is that an SSD is a good choice for a boot drive upon which the operating system and applications have been installed. The increased transfer speeds allow the boot time and application load times to be reduced. The lifetime of computer system is thought by many to be shorter than the lifetime of an SSD before it fails, but evidence shows this may not be true.
If you need to store large quantities of files, such as multimedia files, photos, videos, music and backups, it more sensible to use a traditional hard disk drive. The cost per gigabyte is not the only consideration, as data recovery can be a major issue, especially as such drives are more likely to be transferred from one machine to another, there expected to operate for a much longer time.
NAND flash memory forms the basis of storage on most SSD drives, but each memory cell is only good for a finite number of read/write accesses before it will fail. The TRIM command available on SSDs is used to optimise this, rebalancing the wear across the memory cells. Any process which requires intensive disk access such as editing photos and videos has the potential to decrease the lifespan of the SSD drive. Such activity should be taken into account before deciding which drive to store certain types of files on.
Implications for Data Recovery
Most SSDs interleave the data across a set of memory chips, which makes the process of recovering data following a failure a complex procedure. Direct access to each memory chip is required to secure the raw data, which must then be de-interleaved. As SSD technology is still being developed, with the architecture changing, new data recovery techniques and procedures may be required for each new type of SSD.
A key issue with an SSD drive is that when it fails, the presence of unrecoverable sectors is more likely, which decreasing the success rate and overall level of recoverable files. Hard disk drives are in comparison a stable and mature technology, despite new developments being introduced to increase the capacity and speed of the drives. This means the techniques have barely changed over the last decade or more, meaning they have been honed to perfection.
For RAID systems we recommend using traditional hard disk drives, unless you have a particular application which requires the use of SSD drives to achieve very high transfer speeds. If you do require using SSD drives for a RAID it is important that you have a robust backup strategy and continually monitor the state of each drive, replacing them immediately.
Using an SSD drive for installing the operating system and applications is considered good practice. At DiskEng we recommend using a traditional style of hard disk drive to store user files and data, as the process of recovering files from them is much simpler and far likelier to succeed. It much better to trust your data to a traditional hard disk drive than an SSD.