If you have been keeping up with the storage market lately, you will notice that there has been a considerable drop in prices for SSD hard drives. It has been frustrating to see over the past 4 to 5 years there has not been much changes in the SSD capacities and prices until now. With the TLC (Triple Level Cell) SSD hard drives available, it is the game-changer we have been waiting for. With TLC capacities at almost 3TBs per SSD drive and projected to approach 10TBs per drive in another year, what does that mean for the rotational disk?

That’s a good question, but there is no hard answer to that yet. As you know, in the technology industry, it can change on a dime. The TLC drive market is the answer to the evolution of hard drives as a whole. It is economical because of the high capacity and it is energy efficient as there are no moving parts. Finally, the MTBF (Mean Time Before Failure) is pretty good as SSD reliability was a factor in the actual adoption of SSDs in the enterprise.

MTBF

The MTBF is always a scary thing as that is the life expectancy of a hard drive. If you recall, I blogged some time ago about the “Perfect Storm” effect where hard drives in a SAN were deployed in series and manufactured in batches at the same time. So it is not uncommon to see multiple drive failures in a SAN that can result in data loss. With rotational disk at 8TBs per 7.2k drive, it can conceivably take days, to even weeks to rebuild a single drive. So I think for rotational disk that is a big risk to take. With TLC SSDs around 10TBs, it is not only a cost and power efficiency advantage, but it is also a lower risk when it comes to RAID rebuilding time. Rebuilding a 10TB drive can take a day or 2 (sometimes hours depending on how much data is on the drive). The MTBF rate is higher because SSDs are predictively failed by logically marking active cells, dead (barring other failures). This is the normal wear and tear process of the drive. Cells have a limited number of writes and re-writes before they are marked dead. In smaller capacities, the rate of writes per cells are much higher because there is only a limited number of cells. With the large amount of cells now offered in TLC SSDs, essentially, cells are written to less often as a much smaller drive inherently. So by moving to a larger capacity increases the durability of the drive. This is the reverse for rotational drives as they become more unreliable as capacity increases.

So what does it mean for the rotational disk?

Here are some trends that are happening and where I think it will go.

1. 15k drives will still be available but in limited capacities. This is because of legacy support. Most drives out there are still running 15k drives. There are even 146Gb drives out there that are running strong but will need additional capacities due to growth and/or replacement for failed drives. This will be a staple in the rotational market for a while.

2. SSDs are not the answer for everything. Although we all may think so, SSDs are actually not made for all workloads and applications. SSD perform miserably when it comes to streaming videos, large block and sequential data flows. This is why the 7.2k, high capacity drives will still thrive and be around for a while.

3. The death of the 10k drive. Yes, I am calling it. I believe that the 10k drive will finally rest in peace. There is no need for it nor will there be a demand for it. So 10k drives, so long…

Like anything in technology, this is speculation, from an educated and experienced point of view. This can all change at anytime, but I hope this was insightful.