Why solid-state disks are winning the argument

Why solid-state disks are winning the argument

Count the reasons

Perhaps the most perplexing question I have been posed this year is: "Why should I use SSDs?"

On the face of it, it is a reasonable question. When it was put to me, however, I just sat there staring at the wall, trying to form a coherent thought. Where to begin?

As it was late at night, I decided that starting with a brief history of storage types and then diverging into a full-blown "why spinning rust was sent from hell to make me miserable" rant was probably the wrong approach.

So I flipped the question on its head. What is the business case for the traditional magnetic hard drive?

Missing magnetism
Magnetic media is cheaper per gigabyte than SSDs. Under the right conditions, some magnetic hard disks can do sequential writes faster than some SSDs.

If you accidentally delete everything from a traditional magnetic disk, you can probably recover it. Oh, and the write life on a magnetic disk is significantly better than that of an SSD.

As you can see, there aren't many reasons to buy traditional magnetic disk. It is cheaper than SSD – significantly so, even at the consumer level. Okey dokey, I'm down with that argument; but that's what tiered storage is all about.

I can buy LSI RAID controllers that make great hobo hybrid arrays for the smaller business, and once you are beyond what LSI can deliver, go knock on the door of Tintri, Tegile, Maxta, SimpliVity, Nutanix, or a hundred other storage providers that will help you moosh NAND and rust into a yummy storage sandwich. Tiering is not exactly rocket surgery.

I can think of exactly two very specific workloads in which sequential write speeds matter. The first is "single source, massive capture". This starts at recording high-def video at the low end and scales up to capturing all the data coming in from the Square Kilometer Array at the high end.

Massive amounts of data are coming in, they need to be written and nothing else (such as another user or application) will interfere with that drive during the writing process.

Here, I don't think SSDs are worth it because we don't have good, cheap, fast write once read many (Worm) SSDs yet. Worm is exactly what these scenarios call for – a sort of digital negative, but hopefully with a longer shelf life than film. For now, traditional magnetics are the storage for this type of task.

Archival backup is the second workload where sequential write matters. Using SSDs for backups is stupid for a number of reasons. For instance, they are miserable to extract data from if something goes awry with the filesystem.


GO HERE TO READ IT ALL

http://www.theregister.co.uk/2014/11/07/storage_ssds/