SSD OR HDD for RAID? Ask any person outside the computer industry that question and they will look at you with a blank stare.
However, if you are in the IT industry, you know that SSD stands for solid-state drive, and HDD stands for hard disk drive. What are they though and what are the differences between them?
HDD (Hard Disk Drive)
This is the traditional spinning hard drive that has been found in computers for the past 20 years or more. This type of hard drive uses basic non-volatile storage on the computer, in that it does not disappear as soon as the computer is turned off. That was a great improvement compared to decades ago, when computer information was stored on cassettes or floppy disks.
SSD (Solid State Drive)
This type of hard drive does the same thing, keeping your data while the system is off and booting up your computer, but it does not use a magnetic coating on the top of the platters. Instead, the data is stored on flash memory chips that are connected, retaining data even when there is no power present.
Naturally, SSDs are much more expensive than HDDs and thumb drives.
SSD/HDD and RAID
With HDD, there are plenty of options with RAID since RAID was originally developed for HDD. The RAID option of JBOD (Just A Bunch Of Disks) has typically used HDD for its setup. RAID is essentially a group of HDDs put together to create a redundant array of disks and the operating system sees those as just one large disk. While many use HDD for RAID, there is a trend moving towards SSD as SSD becomes less expensive.
Why should you use SSD RAID? The main reason is that it will improve the performance of the computer by dividing the data and storing it across multiple SSDs.
Putting together an SSD RAID is going to be much more expensive than an HDD RAID. The reason for this is that SSD is approximately six times as expensive as HDD. Nonetheless, the huge benefits of having a SSD RAID make it completely worthwhile. These include the fact that an SSD RAID can bring about an I/O performance that is over 100 times better than a comparable RAID that uses HDD. That is the upper reaches of its improvement but you can guarantee a performance increase of 10 times compared to what you have with HDD.
Typically SSD will use only two watts of power, compared with 10 watts for an HDD. As a result, an SSD RAID is going to use much less power to operate, which saves you money and helps generate lower long-term operating costs. For many companies, having a SSD RAID is well worth the money because the improved efficiency of that type of RAID results in much lower cooling costs, saving the company a lot.
There are of course drawbacks, not the least of which is the fact that SSD costs much more. Another problem is that SSD is much harder to find and the storage capacity is much lower than what you see with HDD. While you can easily find an HDD that is one to four terabytes in size, the highest you will typically find for an SSD is 128 gigabytes, with a few models offering a bit higher than that. SSDs do have life spans comparable to HDDs, the replacement cost is of course much higher than what you see with HDD.
Is SSD RAID that much better?
Despite the drawbacks, SSD is a much better option than HDD, if you can afford it. The performance increases will be much, much higher than you will see with HDD. For larger companies, and larger budgets this is an easy choice to make, but for regular consumers, it may be too expensive to build RAID using only SSD-s at this time.