Category Archives: General

Apple Fusion Drive, At Last A True Tiered Drive

We’ve been talking about the merits of SSD caching vs. tiering for a while now, but at last someone else did it right. Enter Apple’s Fusion drive announced earlier today.

For those needing a technical refresher on caching vs. tiering, see my earlier blog posts SSD Tiering versus Caching: Part 2 and SSD Caching versus Tiering. Unfortunately, confusion still reigns in many of the blog posts we’ve seen today and most people still don’t get what the real difference is. Yes they achieve something very similar, and no, Apple’s approach is not like Intel’s caching or anyone’s caching. It’s an approach like we do at Enmotus with our MicroTiering i.e. we move the data you care about the most onto the faster SSD and make sure the stuff you don’t use a whole lot lives on the slower hard drive. For the technical folks out there, the only difference is that Apple does it at file level and we do it at block level.

For the less technical, the best everyday parallel I can think of is that caching is like staying in a hotel room whereas tiering which is more like living in a home.  A hotel serves as a temporary place to hang out for a specific occasion and leave after a relatively short stay. If the hotel is busy, you generally have to move out after your pre-allotted time with no possibility to stay on. If it’s not so busy, you may be able to extend your stay. A tier on the other hand is more like a permanent home you moved to and where you live, have all your belongings with you and you can stay a whole lot longer, often for the rest of your life. Furthermore, your home is a whole lot nearer the everyday places you go most of the time and it will still be there and available to you every day as long as you need it.

So what’s the fuss about? Apple are the first guys to openly admit and support the notion that tiering is better than caching where SSDs are concerned, which I and the team at Enmotus whole heartedly agree with. Why? Here a few reasons we’ve discovered along the way.

  • Tiering delivers superior performance as it provides the full bandwidth of the SSD to the user for the active portions of your data
  • Almost all of the SSD’s capacity is useable storage and not hidden as with caching. In other words, I paid for this SSD and it visibily adds to my overall capacity and it’s not hidden behind a disk drive.
  • SSDs wear out the more you write to them. Caching increases the number of writes to the SSD and wears them out faster. Teiring is far friendlier. We’ve measured extremely low overhead writes to SSDs using tiering at Enmotus of the order of 0.01% to 1% above and beyond what the host wrote over just a few hours of usage.

Why should we care about tiering? Even the professional vendors of PCIe SSDs agree – skip caching and put all the user data on one large SSD if you can. Problem is, this is just too expensive for us everyday users who are not trying to replace large numbers of disk drives. Tiering provides that perfect balance between performance and cost while providing enough capacity to still store those large videos, photos and games.

The future is definately bright for SSD tiering.

Who moved my cheese … again

I’m reminded yet again as I read the morning news of the volatile times we live in. Job losses (or small gains more lately thankfully) especially in technology and engineering all seem familiar and normal nowadays. Those of you recall the high tech crash of 2002/2003 may remember a book called “Who Moved My Cheese“, an excellent and short story about groups of mice faced with the same challenges, but dealing with them in a different way. BTW, this is a must read for anyone who has either gone through or is facing a new set of challenges either in your personal or business lives, specifically a job loss, company shutdown, products losing steam and so on.

The book basically says (in far more eloquent works that I’ve put here):

  1. Stuff happens… there’s nothing you can do to stop that
  2. Something that was new a while back may now be stale and old
  3. Stop looking to renew something that is at the end of its road
  4. New opportunities are out there for those that look for it – just go.
  5. Make sure you look and don’t wait for stuff to come to you
  6. Never, never give up searching for something fresh and new

Having been through this many times now in both product and personal development situations, this old wisdom is definately on the money and best of all, simple enough even for us tekinerds to understand and relate to. This up and down economy is a norm we all have to get used to and more importantly adapt to. We all have to (continue to) educate ourselves as to what end users or technology really need versus what we can build, and focus on addressing real problems that exist and can be solved. This way, we’ve increased the chances that what we’re working on is relevant and needed.

Whatever your situation, happy adapting… again.