Hard Disk vs SSD Drive

There are many articles comparing traditional hard disks to SSD drives, and the conclusion to be drawn is quite clear, that SSD drives are superior. However, is the picture really that cut and dried?

A major factor in choosing the right drive in the correct situation, largely ignored is what happens if data recovery is required. This should be considered alongside the other factors which determine the correct solution.

Advantages of SSD drives and Hard Drives

The main advantages of SSD drives are the increased speed and the lack of moving parts, so impact damage is much less likely to occur, especially in laptop computers. The lack of moving parts also means that SSD drives make almost no noise, and also consume much less power. There are also many great claims about the reliability of SSD drives.

Traditional Hard Drives however do have a major advantage when it comes to available capacity and the cost per gigabyte. As of March 2015 hard disk drives are available up to a capacity of 8TB, whereas a SSD’s over 1TB are prohibitively expensive.

When to Choose SSD or Hard Drive

The perceived wisdom is that an SSD is the best choice when it comes to the boot drive, containing the operating system, and the installed applications. This will give improved boot speed, and application start up. It is thought that most computer systems will be replaced through obsolescence before a failure of the SSD drive occurs.

For storing data, especially those collecting large quantities of multimedia files, photos, videos and music, a traditional hard disk drive makes more sense. This is usually only based upon the cost per gigabyte, but data recovery becomes an issue, as drives containing data files, are often moved from one machine to another, so have an increased operational lifespan.

Most SSD drives use NAND flash memory to store the data, but only a finite number of read/write accesses can be made to a memory cell before a failure will occur, although the TRIM command is used to optimise this. Large scale editing of photos and videos can lead an excessive amount of file access, which could lead to the very fast failure of an SSD drive, so the type of activity should also be taken into account.

Data Recovery Implications

It is important to understand that the data stored in an SSD is usually interleaved across the memory chips. SSD data recovery following a failure is a complex process, requiring direct access to the memory chips, in order to access the data, which must then be de-interleaved. SSD technology is still developing, making the architecture and implementation a moving target for data recovery.

At this point in time the success rate for SSD data recovery is considerably lower than that for hard drive recovery. Hard drive technology is now a mature and stable technology, and although advances are still being made, the techniques used during the data recovery process remain almost identical to those perfected decade or more ago.

While placing the operating system and applications on an SSD drive is good practice, DiskEng recommend still using traditional hard disk drives to store your user data. It is often the case, that when you buy a new machine, the drives containing your data will be physically transferred to the new computer, so the long term safety of your files is still best served by entrusting it to traditional hard disk drives.

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