Pooled Storage + Flash Drives = Innovation

Despite what some vendors would like you to believe, and have been somewhat successful in convincing all other storage vendors placing Flash drives into Enterprise Storage Arrays alone are not innovative in any sense of the word. Solid state drives are not new, and storage arrays are not new. Simply applying existing raid, provisioning, and etc. mentalities is not innovation.

However it is a step in the direction of innovation. By having the ability to utilize these devices in an Enterprise Storage Array it does open the door. The next step is coming up with a full proof method of placing the data and only the data which benefits the most from this type of technology onto these devices intelligently and without an impact to the application.

So what benefits the most from this technology? This is an easy one. Things that make the disk drives spin the most. The biggest nightmare to anyone with storage performance experience drum roll please ..... Random Read Misses. So lets put all our random read misses on flash drives. Well this is where we run into the problem.

Lets consider one application which is not performing up to par. You have a case open with your storage vendor, and aren't making much lead way. After a couple days the sales guy catches wind, and comes in with the solid state drive sales pitch. So everyone is blown away by the "innovation" and jumps on board. Now its time to actually spec out the hardware.

Here in lies the problem what do you place on the solid state drives? One option is to place the entire application on solid state drives. The sales team will definitely be on board with this option. However since the majority of writes go to cache, and the majority of sequential reads take advantage of prefetching algorithms this would result in alot of data on solid state drives that do not have an IO profile which warrants such placement. The other option today is to look at the performance data and identify identify individual luns with high random read percentages. Once these luns are identified they could then be manually moved utilizing a back end storage utility without an outage, or a planned host based mirror/migration.

So whats the problem, and why is this not innovative?

1. All of this is a manual method.
2. Since a lun is the smallest object you can migrate today you are still moving too much data to solid state drives.
3. It is possible to have a small portion of data on a lun with a high random read miss percentage which cannot be identified because it is masked by the IO pattern of the remaining data on the lun.


So how do we address these issues? Well the answer to the second and third is by moving towards pooled storage. With pooled storage the smallest denominator becomes an extent. Now for the innovative part is the array identifying the extents which are the best candidates for placement on solid state drives, and being able to move them there on the fly without downtime. Now that would be disruptive innovation.