What are the pros and cons of a solid-state drive?

Question

_{There's already a thread here about the pros and cons of SSDs that has a lot of votes, so it tends to show up towards the top when you search for SSD info on here. Unfortunately, a lot of the info about pricing, reliability and performance is badly out of date.}

Now that SSDs are cheaper, faster and presumably more reliable, what are the pros and cons?

Answer 1

The Pros

• Very short random access times - usually less then 0.1ms. For contrast, hard disk drives (HDDs) typically have access times of 5-10ms. An SSD should also have constant access time, whereas HDDs experience jitter depending on the prior location of the read/write head.
• Drastically improved sequential transfer speeds, partly due to the parallelism of flash chips. New SSDs can max-out a SATA 3 Gbit/s bus; PCIe-based SSDs can reach over 700 MByte/s (5.6 Gbit/s).
• No moving parts, very resistant to shock (many drives can withstand over 1000G), and absolutely silent operation.
• Small form factor (most drives are 2.5", some are PCIe which leaves more drive bays open), very light.
• Good performance for both sustained and random reads/writes (mostly due to lower latency).
• Not susceptible to magnetic fields (but are susceptible to radiation, like all other flash/DRAM).
• Relatively low power consumption (flash-based SSDs only, see other notes below).

---

The Cons

• MLC based drives have a maximum write count (often called the program/erase count) of 3,000 to 10,000 per block; SLC based drives have a maximum of 100,000 (assume half for realistic purposes). I highly encourage all SSD users to make backups of their data frequently for this reason. Nevertheless, data should be readable until roughly one year after an SSD has fully worn out.
• Some drives have a tendency to fail without warning (although this is most likely due to the failure of the SSD's controller, it is also possible for the flash memory to wear out, albeit slower). As an end-user, you should continually check the drive's S.M.A.R.T. information and check the drive health often.
• SSDs are still far more expensive then conventional HDDs on a $/unit storage ratio.
• Low storage density compared to conventional hard drives.
• Professional drive/data recovery techniques for SSDs may not be as successful, because SSDs are a relatively newer technology compared to HDDs (thanks Moab), so the techniques may not be as advanced yet.

---

Other notes: DRAM-based SSDs do not have many of the caveats mentioned above, and are much quicker then flash-based SSDs. They are, however, significantly more expensive then flash-based drives, and require the DRAM cells to be constantly powered (similar to keeping your computer on standby/sleep mode). Also, DRAM requires significantly more power when in use compared to flash-based SSDs.

---

What to take from this: There is no denying the fact that SSDs are pretty damn fast. I installed one in my new computer a few weeks ago, and I can honestly say transfering files at 500 MB/s is a great feeling. That being said, there is the fact that the SSD will wear down over time, and from my usage patterns so far, it will be a few months to a year. This depends on how you use the drive, but I would still recommend that you check your drive's health often. FWIW, Corsair has posted a good blog post about write endurance.

While newer drives are proving to be more reliable, this isn't due to any increases in the write endurance of flash cells, but rather improved controllers and firmware (thanks sblair). Because of this, as an end-user, you need to be aware of this fact and make frequent backups. If you have very important data and any data loss is unacceptable, then you may want to spend the money on an extra hard drive (or two!) instead of the SSD. If you have a blazing fast gaming machine, and want the thing to load as quick as possible, definitely go for the SSD. My recommendation is, if you want both speed and reliability, get both a solid state drive and a hard disk drive.

Answer 2

Here's the latest article on SSD reliability. They are actually pretty reliable, but the speed difference is so great that for large systems they are well worth any decrease in reliability. Intel has just extended their warranty to 5 years.