If you’ve been tracking current issues concerning storage, you know that solid state drives (SSDs) are a popular option as growth-minded enterprises upgrade their systems. Of course, making the decision to upgrade can pose more detailed questions regarding the shape and size of the SSD, or the form factor. There are five primary options available: 2.5-in. SATA SSDs, 2.5-in. NVMe SSDs, M.2 SATA SSDs, M.2 NVMe SSDs and mSATA SSDs.
But first — how did we get here?
IT managers may be looking to upgrade older systems with hard drives to SSD, or older SSDs to newer, faster, more efficient or higher capacity SSDs. Since SSDs are now in the third and fourth generation, speed, response time and the overall lifetime of the drives have greatly improved.
The choice of SSD is generally guided by the interfaces available in the system, whether laptop, tablet, PC or server. The first step is to determine what types of storage connections exist and what other options might be available, such as open PCIe slots that can take PCIe storage adapters to allow the use of newer, faster drives.
Many SSDs are currently made in 2.5-in. form factors. The original 2.5-in. drive was a hard drive, the end result of an evolutionary trail that began with 16-in. hard disks in the 1950s and ended with one inch microdrives around the turn of the century. While the one inch drives never became popular, the 2.5-in. drives are still around and are being used in many devices.
The 2.5-in. SSD is in the same size case, and the only reason for the case is to fit into the same receptacle in laptops, servers and other computing devices. Indeed, the 2.5-in. case poses some problems for SSDs: it reduces cooling efficiency and takes up more space than necessary. With newer options available, there’s more to consider.
2.5-in. SATA SSDs
The 2.5-in. SATA SSD is now in its fourth generation, and comes with improved speed, originally at 100 MB/s, now 300 MB/s to 550 MB/s or better — typically at the maximum that the SATA interface will allow. Longevity of the drives are much longer than that the first generation SSDs, which may only last a year or two. A typical 2.5-in. SSD is the Samsung 860 EVO as well as the Samsung 860 PRO.
2.5-in. NVMe SSDs
The 2.5-in. NVMe SSD offers the ability to go faster than the SATA bus can support. By using the newer NVMe standard (with the latest spec being NVMe 1.3a or 1.4), drives can sustain throughputs as high as 3,500 MB/s, compared to the 550-600 MB/s that the SATA bus supports. Input/output operations per second (IOps) are also as much as ten times higher, going from around 50,000 IOps in a SATA drive to as many as 500,000 IOps with NVMe. A typical 2.5-in. NVMe SSD is the Samsung 983 DCT, which looks like a 2.5-in. SATA SSD but operates with an NVMe interface and performance.
M.2 SATA SSDs
The newer M.2 form factor is more compact than the 2.5-in. SSD and offers a choice of SATA or NVMe interface. M.2 drives are 22mm wide and may be 30mm, 42mm, 60mm, 80mm or 110mm long. M.2 SATA SSDs, like the Samsung 860 EVO M.2 SATA, offer the smaller form factor that goes with M.2, but with the less expensive SATA interface — ideal for applications where the highest level of performance is not necessary.
M.2 NVMe SSDs
The latest type of SSD available is the M.2 NVMe SSD. It combines the faster NVMe interface with the compact M.2 form factor. It offers high levels of performance, with up to 3,500 MB/s throughput and up to 400,000 IOps, along with lower power consumption and more efficient power usage than the 2.5-in NVMe. One example of a typical M.2 NVMe SSD is the Samsung 970 PRO, Samsung 970 EVO, and Samsung 983 DCT.
mSATA SSDs use a compact format similar to M.2, but with a 30mm width and 50.95mm length. These drives are uncommon, primarily being used in some tablets and notebooks where space is at a premium. A typical mSATA SSD is the Samsung 860 EVO mSATA. The mSATA and 2.5-in. SATA SSDs typically have very similar performance statistics — about 550 MB/s for sequential reads in the 860 EVO, and 520 MB/s for writes.
There are also mPCIe cards, which use the same connector as the mSATA, but connect to a PCIe host controller or USB controller, rather than a SATA controller.
Which one’s right for your device?
When buying your next SSD, keep in mind the device you’re seeking to upgrade, whether it’s a laptop, desktop or server. Here’s a further breakdown on how to evaluate for each:
For laptops, you may have a space for one, two or four 2.5-in. SATA drives, or for two M.2 slots and one 2.5-in. SATA drive, or for one or two mSATA drives. Also know that laptops with M.2 slots may have one or two that are either SATA or NVMe slots. To upgrade with new drives, you have to know what type of slots it has, as the these will determine which SSD drives will fit. For any laptop that was built within the last 20 years or so, the hard drive is likely to have a 2.5-in. SATA drive. These can be replaced with 2.5-in. SATA SSDs like the 860 EVO and 860 PRO.
For desktop systems, most have been limited to SATA connections up until the last couple of years. Some motherboards now support NVMe slots and “sleds,” PCIe cards that can hold as many as four M.2 NVMe SSDs. While there are many applications that won’t see much improvement going from SATA to NVMe, games, graphics creation programs, data mining and other specialized apps can take advantage of the 6x performance gains offered by the best NVMe drives.
On the other hand, many desktop systems come with 3.5-in. hard drives. If you’re interested in replacing these with SSDs, there are inexpensive adaptors that allow you to mount a 2.5-in. drive in a 3.5-in. bay. The interfaces are the same for both: Any SATA SSD should be able to use the same cable that was originally plugged into a 3.5-in. SATA hard drive. Any system with a free 4x PCIe slot can use a sled and one or more PCIe SSDs, although older motherboards that don’t support PCIe 3.0 or greater may not work well with sleds, and even if they do, their older backplanes may not support the full speeds necessary to get the most out of the newer NVMe SSDs.
For servers, newer models are now being designed with 2.5-in. SSDs and NVMe SSDs in mind. They can support 20 2.5-in. NVMe drives or as many as 36 M.2 SSDs. Upgrading older systems with new drives requires the same investigation as with laptops or PCs — determine what types of interfaces the existing drives use, and replace them with SSD models that use the same interface.
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